NTNU Norwegian University of Science and Technology Faculty of Engineering Department of Mechanical and Industrial Engineering
Master ’s thesis
Eigil Reppe
Development of a Rehabilitation Apparatus forWhiplash Patients
Master thesis in product development
Master’s thesis in Product Development Supervisor: Knut Einar Aasland
July 2020
Development of a Rehabilitation Apparatus for Whiplash Patients
Eigil Reppe July 10th 2020
Abstract
Firda Physical Medical center is a physiotherapist specialist center that specialises in treatment of whiplash injuries. They have needs that are not fulfilled by their current equipment and have contacted NTNU for a collaboration. They wanted a solution that provides more freedom of movement and possibilities of personal- ized exercises for their patients.
This Thesis is a continuation of the development of this rehabilitation apparatus.
I will be going through earlier work and concepts, especially related to the part in which I focus. My main focus is the development of the connection between the head of the patients and the apparatus.
During this thesis I will discuss product development strategies. How they relate to my work. I will be testing both earlier solutions and my own solutions, compare them, and discuss which is better.
Finally I summarize tests and performance of my solution. I am arriving on a solution that I believe meets the overall goal of this project. Which was to design an improved functioning prototype of a fastening mechanism between head and robot.
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Sammendrag
Firda fysikalsk-medisinsk senter er et fysioterapeut spesialistsenter som spesial- iserer seg i behandling av nakkeslengskader. De har behov som ikke blir oppfylt av deres nåværende utstyr og har kontaktet NTNU for et samarbeid. De ønsket en løsning som gir mer bevegelsesfrihet i øvelsene og muligheter for å tilpasse øvelser til sine pasienter.
Denne oppgaven er en fortsettelse av utviklingen av dette rehabiliteringsappar- atet. Jeg skal gjennomgå tidligere arbeid og konsepter, spesielt relatert til den delen jeg fokuserer på. Mitt hovedfokus er utviklingen av forbindelsen mellom hodet til pasientene og apparatet.
I løpet av denne oppgaven vil jeg diskutere produktutviklingsstrategier. Hvordan de realt til arbeidet mitt. Jeg skal teste både tidligere løsninger og mine egne løs- ninger, sammenligne dem og diskutere hvilke som er bedre.
Til slutt oppsummerer jeg testing og ytelsen til løsningen min. Jeg kommer frem til en løsning som jeg mener oppfyller det overordnede målet for dette prosjektet.
Å utforme en forbedret og fungerende prototype av en festemekanisme mellom hode og apparat.
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Contents
Abstract . . . iii
Sammendrag . . . v
Contents. . . vii
Figures. . . ix
1 Introduction . . . 1
1.1 Background . . . 1
1.2 Problem Description . . . 2
1.3 Agenda . . . 2
2 Previous Work . . . 3
2.1 Multi Cervical Unit . . . 3
2.2 Stewart Plattform . . . 4
2.3 MASNAK . . . 4
2.4 Cable robot . . . 5
2.5 Robot arm . . . 6
2.6 Helmet and Mounting Mechanism . . . 6
2.7 Chair . . . 7
3 Theory . . . 9
3.1 Anatomy of the Neck . . . 9
3.2 Whiplash Injuries . . . 9
3.3 Treatment . . . 10
3.4 headsize and shape . . . 11
4 Method . . . 13
4.1 Product Development . . . 13
4.1.1 Prototyping . . . 13
4.1.2 Set based design . . . 14
5 Concept . . . 17
5.1 Requirements . . . 17
5.2 Earlier Solutions . . . 17
5.2.1 ETTO Helmet . . . 18
5.2.2 3D Printed Helmet With Inflatables . . . 18
5.2.3 Solution from the MCU . . . 18
5.3 Fastening concept . . . 19
5.4 Designing the helmet in Solidworks . . . 20
5.5 Designing new helmet from scratch . . . 21 vii
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6 Testing. . . 25
6.1 Testing the MCU . . . 25
6.1.1 How designs are Tested . . . 26
6.2 The optimal test setup . . . 28
7 Conclusion . . . 31
7.1 suggestion going forward . . . 31
Bibliography . . . 33
A Additional Material . . . 35
Figures
2.1 A model of the MCU in use[3] . . . 3
2.2 Schematic drawing of the Stewart platform[4]. . . 4
2.3 Picture of the MASNAK in use (from Berg and Sundes Thesis) . . . 5
2.4 A model of the cable robot[5] . . . 5
2.5 The Franka Panda robotarm[6] . . . 6
2.6 A picture of the magnetic connection . . . 7
2.7 A picture of the slider . . . 7
3.1 A model of the MCU in use[10] . . . 10
5.1 ETTO helmet . . . 18
5.2 3D printet helmet with inflateables . . . 18
5.3 Applied forces with previous solution . . . 19
5.4 Applied forces in new concept . . . 19
5.5 Starting point of first model . . . 20
5.6 Printable first prototype . . . 20
5.7 . . . 21
5.8 . . . 21
5.9 . . . 21
5.10 . . . 22
5.11 . . . 22
5.12 . . . 22
5.13 . . . 23
5.14 . . . 23
5.15 . . . 23
6.1 . . . 27
6.2 . . . 27
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Chapter 1
Introduction
This Master thesis is a continuation of previous Master theses and my specializa- tion project in the autumn of 2019. The goal of this thesis is to continue developing a machine for retraining patients after whiplash injuries, mainly focusing on the fastening mechanism between the head of the patient, and the end defector of the robot arm.
1.1 Background
"Whiplash injuries are a common problem after both sporting and car accidents.
It is estimated that about 4000 Norwegians suffer from symptoms after car and sporting accidents in Norway. Car accidents and sports accidents are the most common but not the only way these injuries happen. Whiplash is a form of injury that in worst-case scenarios can have life long effects. About 10 percent of people with whiplash injuries have symptoms after 6 months.Thus, about 400 people a year get long-lasting issues with their neckNakkesleng - NHI.no[1]
Today’s solution for rehabilitation of neck injuries is insufficient according to Firda Physical Medical Center (Firda Physmed). Firda Physmed is one of the few special- ists centers on neck trauma in Norway. Their physiotherapists need functionalities that their current apparatus doesn’t meet. Therefore, they contacted The Norwe- gian University of Science and Technology (NTNU) to initiate a partnership that started in 2014. Since then several projects and master theses have been written on the subject. Several ideas have been tested to meet the needs of Firda Physmed.
The last few projects have focused on a robot arm concept that appears to be a good solution. However, there are still some issues that have to be resolved” – Specialization project.
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1.2 Problem Description
The problem to be solved is that today’s solution for rehabilitation of whiplash injured patients need rehabilitation, the multi cervical unit, does not meet the demands of the physiotherapist treating these patients. An improved solution is needed. The main issue being lack of freedom in movement, and that it has a inadequate fastening mechanism. A robot-arm concept has been worked on, but still have some issues mechanically and on the software side.
1.3 Agenda
The goal of this project is to continue and improve the work that has been done in earlier projects. My goal is to design an improved functioning prototype of a fastening mechanism between head and robot arm.
Chapter 2
Previous Work
In this chapter I will quickly go through what has previously been achieved within this project as well as previous student’s considerations of the same project.
2.1 Multi Cervical Unit
The Multi Cervical Unit (MCU) is the solution used by Firda physmed Today and is according to Firda Physmed, the best available system on the market today. It is also marketed as "The most effective and complete system for the assessment and rehabilitation of patients suffering from neck pain"[2]. However, this appar- atus does not meet the needs and wants of the physiotherapists at Firda physmed.
Figure 2.1: A model of the MCU in use [3]
This machine works by fastening the head, as can be seen in the picture to the left, and then a cord is fastened to the head in one end with weights at the other end. The weight is adjustable. The head can also be locked and the force exerted by the head can be measured. However, this function was not much used at Firda physmed. There is also a computer and software that comes with this machine.
Although it has a graph and overview function, Firda physmed did not find this useful. The graph is in a too small win- dow that can’t be expanded, and it has to low resolution. Morten Leirgul said that this graph function was mostly used to show and explain the treatment to pa- tients but gave no information of value to the physiotherapists.
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The chair itself has a belt system that helps to keep the body in the right position.
These belts cross the shoulders and keeps them tight to the chair. This system works in a satisfactory way.
2.2 Stewart Plattform
The first concept for an improved rehabilitation apparatus was developed in the master thesis by Kristoffer Bjørnerud Slattsveen and Sondre Frantsen Tolo in 2015.
One of these concepts is the Stewart platform.
Figure 2.2: Schematic drawing of the Stewart platform[4]
The Stewart system itself is a plat- form with six prismatic cylinders which can be pushed up and down, and all connections are designed with universal joints.A figure depict- ing the platform can be seen to the left. An item placed on the top plate of this platform can be moved in all the six degrees of freedom (DOF).
Because of this, some also call this platform a 6-DOF platform or a six- axis platform.
Even though this solution seemed promising and work were continued with the project of Ole Jacob Berg and Øystein Kavle Sunde in autumn 2015. they decided to abandon the Stewart platform. The main arguments for this was uncertainty regarding the robot technical and safety for the patients. They also found that the Stewart platform was problematic due to large movements at the joints and the with fastening of the head.
2.3 MASNAK
After deciding that the Stweart platform was not good enough Berg and Sunde continued with the MASNAK concept, a multi-joint mechanism with a parallel structure. This solution has four linear actuators that work passively against the movement of the patient.
Chapter 2: Previous Work 5
Figure 2.3:Picture of the MASNAK in use (from Berg and Sundes Thesis)
2.4 Cable robot
Gælok and Strand were in their master thesis for 2017 supposed to continue with the MASNAK, but after talking with Firda Physmed, they decided that its inabil- ity to move in all degrees of freedom was insufficient. Therefore, they decided to continue with a cable robot concept
Figure 2.4: A model of the cable robot [5]
The cable robot is a robot based on cables attached to winches, an illus- tration of this concept is shown to the left. With this concept, the num- ber of degrees of freedom can be controlled by the number of cables.
The winches are connected to a computer that can control the cable lengths or resistance in the winches.
The Cable robot was abandoned after talking to a professor at the Fraunhofer In- stitute for Manufacturing Engineering and Automation in Germany. They learned that the actuators were too expensive and that getting the precision needed would be very hard due to lack of experience in the field, and some uncertainties regard- ing medical safety.
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2.5 Robot arm
In their thesis, Gælok and Strand landed on the Robot arm as the concept of choice.
They used a Robot arm called the Panda robot made by Franka[6]. This robot arm has a feedback system based on torque sensors. The principle behind this solution is that the robot arm will act against the patients’ movement, while the amount of resistance can be adjusted.
Figure 2.5:The Franka Panda robotarm [6]
The robot arm is a widely used ap- paratus, especially in the industry and is also becoming more common in medical uses, and in uses where they are working in collaboration with humans. The selected Panda ro- bot is shown to the left, and was chosen because it had "7" degrees of freedom, (these robots are said to have an extra degree of freedom, but actually has one extra joint to avoid singularities which can appear in a robot with one less joint). They also selected this Robot due to its low price, its precision of 0.1mm and be- cause, according to its producer, it can be guided with almost no resist- ance.
2.6 Helmet and Mounting Mechanism
In the first theses, the idea was to have ETTO, an alpine helmet creator make a helmet specifically for this task, but even though Etto was excited about the project, they didn’t have the resources for it and it was decided that this solution would be too expensive. However, they recommended one of their alpine helmets, which was customized by Brattgjerd in his specialization project in 2017. This solution proved to be too heavy and loose, therefore Baardsgaard and Brekke decided to improve on this concept and 3D printed their own solution and tested it, which is the point of development where we are prior to this thesis.
Chapter 2: Previous Work 7
Figure 2.6: A picture of the magnetic connection
The helmet has a magnetic connec- tion, one of the benefits with this solution is that the helmet itself de- taches easily, thereby makes the ro- bot safer because if the robot sud- denly moves due to a programming error or other technical difficulty, the helmet would detach. This connec- tion is strong if pulling it straight down from the arm, but if pulled at skewed it will easily be detached.
The magnetic connection also en- ables connecting different end de- fectors quickly, thereby also giving the the opportunity of conveniently switching between helmets of differ- ent size
Figure 2.7:A picture of the slider
This solution also has a slider in which the position of the magnet ring can be adjusted forwards and backwards along the helmet. This slider can be seen in figure 2.7 to the left.
2.7 Chair
Several solutions have been suggested for the chair.In some the patient can be standing up, or even walking. The current solution is a chair and robot mounted together, where the chair is a chair with belts to hold the person in place. The chair is seen as the best solution because it gives a more consistent posture, while other solutions allows patients to "cheat" to make the exercises lighter. This can be done by helping the movement by adjusting posture, which is harder to do when sitting down strapped.
Chapter 3
Theory
To know more about how the different solutions compare, it is important to know some basic theory about both the neck and whiplash injuries, and how these in- juries are treated
3.1 Anatomy of the Neck
The neck is one of the more complex parts of the body, it is movable in several directions, (The neck provides the Head with 6 degrees of freedom) and also contains vital organs such as the spinal cord, blood vessels to the brain and nerves.
Brennanet al.[7]Because these are so vital to protect, torn muscles and ligaments do not heal in the same way as in the rest of the body. The cervical spine (The spine in the neck region) is made up of 7 vertebrae, usually referred to as C1-C7, where the two on the top C1 and C2 are highly specialized and are given unique names, Atlas and Axis, The joint between these vertebrae are responsible for 60 percent of the rotation. These two vertebrae differ from the next five, as the next five are more classic vertebraeCervical Instability - Physiopedia[8]
3.2 Whiplash Injuries
The definition of a whiplash injury is controversial. The essential elements are that the injury takes place in a motor vehicle accident and that the head is subject to acceleration forces that result in bending of the neck.Barnsleyet al.[9]However, in this project I will be using whiplash as a term for all whiplash related accidents, even those not happening in motor accidents
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Figure 3.1:A model of the MCU in use[10]
A whiplash injury is an injury caused by a sudden jolt in either the forward, back- ward or sideways direction. It occurs when the soft tissues in the neck get stretched too far or tears. Most whiplash injuries are healed within a few months, but in some cases this injury can last for a long time or even their entire life.Whiplash - NHS[11]. Common causes of whiplash injuries include motor accidents, sporting injuries, or falls containing head trauma
3.3 Treatment
Whiplash will often get better on its own after some basic treatment. Treatments for Whiplash include keeping your neck mobile and continuing with your nor- mal activities, painkillers to help relieve the pain, physiotherapy, exercises, and stretches. At prolonged pain, a specialist may be contacted (such as Firda Physmed in Sandane) and in some extreme cases, patients might undergo surgeryWhiplash - NHS[11]
Firda Physmed in Sandane. has specialised in this kind of treatment. They usu- ally treat their patients through exercises. Today, they are using the MCU which was described in chapter 2. They use this machine to strengthen the muscles in the neck to help the neck rebuild lost functionality. They do this by moving the head in set directions, with or without resistance in the apparatus, depending on the level of injury and how far in rehabilitation the patient has come. Treatment is also often individually adapted depending on which ligaments or muscles are torn With this new apparatus being developed, they hope to gain more control over the patients movements, and not just movement in one direction at a time, in ad- dition to more personalizing to better fit each patients need better. This is to be done through the robots ability to save movement patterns. And also its ability to make movements in more than one axis at a time tom better fit the specific injury
Chapter 3: Theory 11
of the patient.
3.4 headsize and shape
The average male head is about 57cm in circumference while females are about 55cm. Lee et al. [12] While the largest measured head circumference from this study was 61.4 cm and smallest 53.4cm, I am aiming for a helmet that fits all in- tervals between these extremes. When looking at the head from above it is shaped like a mix between a square, and an "eliptic shape" as the head is not completely circular this can be exploited to avoid friction in fastening a helmet.
Chapter 4
Method
4.1 Product Development
Product development is the action of improving or creating a new product to fill the needs of the customer or user. In the case of this thesis, improving a way to retrain patients after a neck injury.
4.1.1 Prototyping
Prototyping is defined as an approximation of a product along one or more di- mensions of interests. While prototyping is considered the act of making such a product. Ulrich and Eppinger[13]prototypes are often used for verification and validation. Ulrich and Eppinger also claim that in new product development, pro- totyping serves four purposes
• Learning
• Communication
• Integration
• Milestones
In their article Blindheimet al.[14]looks at iterative prototyping combined with a set based approach. They found that new requirements can be found using this method, and that building physical prototypes can be useful in finding the solu- tion space.
In this Thesis I will be using prototypes for these purposes, learning what can be done better, communicating my ideas, and checking the integration of such ideas. Prototypes will also serve as natural milestones as they show progression.
Desig-Thinking
According to Seidel and Fixson [15]prototypes can also be used in a "design- thinking" way. In design-thinking, prototyping takes on a different role, in which
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the main goal is to facilitate the development and transfer of new ideas into pre- liminary models that can be evaluated. Brown[16]argues that prototypes can be used as a tool to "get going" Brown also claims that by taking the time to prototype ideas, costly mistakes such as becoming too complex too early and sticking with a weak idea for too long is avoided. In this sense design thinking is a prototype driven development process, or philosophy. It is common practice for develop- ment teams to build and test prototypes from the very beginning of the project.
This means speed is crucial, and how fast the team is able to build prototypes and implement lesson learned in the next iteration is a critical factor for progress Elverumet al.[17]
Experience Prototyping
The main difference between experience prototyping and most other types of pro- totyping is that in experience prototyping there is an active engagement with the prototype instead of a more passive approach Buchenau and Suri [18]. In es- sence, experience prototyping means using a prototype to demonstrate ideas and concepts to stakeholders so that they feel or understand how the product perform.
Experience is subjective therefore the best way to understand how well people will like a product is to try it. According to Buchenau and Suri[18] experience prototyping is favourable in cases in which user experiences and context is under- stood. Also exploration and evaluation of design ideas should be communicated to an audience. Experience prototyping can be useful also in cases where the dir- ect experience is unsafe, too expensive or unavailable.
With respect to the current thesis, this means that testing and experiencing how the solution works can give valuable insight into how a patient will feel using the same or a similar solution. For example, when testing the MCU at Firda Physmed, I got to know how the old solution feels, which gave insight into how it could be improved.
Thus, this thesis will prioritize making prototypes and improving them, rather than making one digital model of one concept and make a lot of time-consuming calculations.
4.1.2 Set based design
Set-based design is a term for going forward with many different designs(sets) and parts simultaneously, to learn more about the different solutions before choosing a single one. This strategy may be used to avoid extra work later in the process.
The logic behind this is that generation of the required knowledge is required before making decisions. Another part of set-based design is to avoid setting the
Chapter 4: Method 15
final requirements early in the process but rather use ranges that can be refined during the process. Instead of making choices, one should make constraints. An- other important part of set-based design is to avoid making a final decision before absolutely necessary. Elverum[19] The main benefits with set-based design are, as mentioned, to reduce re-work and increase flexibility,
thus, designing a model wherein the different parts of it can be altered without compromising the rest of the solution. For example, with the helmet, the shape can be looked upon as one set, while fastening of clamps another, and the mag- netic connection a third, since all of these can be changed without affecting the others.
Chapter 5
Concept
5.1 Requirements
When working on the specialization project, I had a meeting with Firda Physmed in Sandane. There I got to learn the requirements of the apparatus. These require- ments were:
• An easy method to monitor and store important data.
• Smooth movements of the machine.
• Sensors or some other way of measuring how different individuals use their muscles and ligaments.
• The machine must be able to move in more than one degree of freedom at the time, but still with the ability to lock some of the degrees, in order to be adaptable to individual patient’s requirements.
• There must be low resistance in the movement of the robot. Resistance may be adjustable, but of most importance, there is almost no resistance, and also close to zero delay in the movement of the robot.
• The solutions must be user friendly and set up should not take much time.
• 3D projection of the patient’s movement is wanted, (a projection could ac- tually be better than a video since it is easier to follow the movement on a model that only does the movement and nothing else).
• The apparatus should be usable for all patients.
Not all of these requirements are relevant, since many of them are associated with the software part of the project. Also, some of them are "cool to have" features, that would be time-consuming to focus on in the first versions, diverting focus from the main features. The first version should focus on making the main features of the solution as good as possible. Some of them could be useful in future projects.
5.2 Earlier Solutions
Some earlier solutions have been tested for these requirements. These are briefly explained below with explanation why they don’t meet the requirements.
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5.2.1 ETTO Helmet
One of the considered solutions is to use an ETTO alpine helmet and modify it so that it can be fastened to the robot arm. This has also been considered in earlier projects.
The weaknesses of this solution are that it requires a specific helmet size for dif- ferent users. The helmet is also too loose even if the size is right, and due to the weight of the helmet, it reduces the cap- abilities of the robot arm. Also, the act of putting on an alpine helmet that is tight
can lead to unwanted strain on the neck. Figure 5.1:ETTO helmet
5.2.2 3D Printed Helmet With Inflatables Another solution that has been con-
sidered is a 3D printed helmet that con- tains inflatable pads. This solution was good regarding fitting different head shapes, but the air pads made it a little
"bumpy", which can result in jolts that feel uncomfortable for the user. The slid- ing mechanism for the magnet holding ring also extends the distance from end of robot arm to center of rotation. which inhibits movement
Figure 5.2:3D printet hel- met with inflateables
5.2.3 Solution from the MCU
Also considered, was copying the solution on the MCU that is already in use, which consist of four clamps, all aligned to the center of the head. It was decided that that this was an imperfect solution that could be made better. As stated earlier, the major weakness of the MCU is that the clamps slip when rotating the head, and the fact that it only allows for movement in one degree of freedom at a time, and that it has little movement freedom in other than the set directions.
Chapter 5: Concept 19
5.3 Fastening concept
The Old solution used at Firda, is based on four clamps where all the force vec- tors meet in the center of the head. How this works when rotating the head is demonstrated in the picture to the right.
This solution is solely relying on friction forces during rotation. This gives poor fastening when rotating the head from side to side, not only because it might slip, but also because the skin of the head itself slips on the skull which leads to a feeling of looseness. I am solving this by moving the clamps as seen in picture
two. Figure 5.3:Applied forces with pre-
vious solution
In this solution six clamps are needed (one in the front, one at the back (in addition to those depicted). These are needed for the forward and backward movements of the head instead of only the four clamps, since the helmet need to be tightly attached when doing the tilting motions in the forward-backward direc- tion. I do not see this as an issue, except that the helmet need to be designed so that there is room for a clamp in front, and that it might take a little longer to fasten it. This was a concern, but accept- able as long as the helmet could stay fastened all throughout all “exercises”, which it could.
Figure 5.4: Applied forces in new concept
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5.4 Designing the helmet in Solidworks
Solidworks is a program used to design either parts or assemblies. The models that are created can from there be made into machine drawings, or files that can be 3D-printed.
At first, when trying to make a new model for the helmet, I decided to use the Cad file from the earlier projects, a model of a helmet delivered from ETTO hel- met company. I did some alterations on this helmet, like cutting out the lower parts of it and cutting off the front, thereby I could test the clamps on the side while also 3D printing it in one piece.
The model I started with is shown in the picture to the left. It is very similar to an alpine helmet, and had to be tweaked to fit my purposes.
This model was cut and tweaked, andmade much thinner.By cutting off the front and some of the back it fitted into the printer.
Figure 5.5:Starting point of first model
When finished tweaking the model to fit my needs for a prototype, it looked like the model to the right.
This model was good enough to test the clamps on rotational movement, and wether the shell thickness was strong enough.
Figure 5.6:Printable first prototype
Chapter 5: Concept 21
After printing, I ended up with a helmet very similar to the model. Then I drilled holes in it for placement of the clamps. I drilled four holes only, since this was a prototype meant for testing the rotational force application of the helmet. See pictures below. As can be seen from the helmet fastened on my head in figure 5.7, there is room to improve the helmet by moving the front clamp even further forward. Also for fitting to my head, the helmet should be made longer in the longitudinal direction to make room for clamps in the front and the back.
Figure 5.7 Figure 5.8
Figure 5.9
After working with this model for some time, I found it too time- consuming, struggling with parameters not working with each other when changing them. I therefore made a new model from scratch, trying to keep it simple with easily changeable parameters. This was done to enable quick changes in the model later if needed.
5.5 Designing new helmet from scratch
The design for the new helmet was performed with Solidworks, firstly, I down- loaded a model of a head to fit the to helmet around (see figure 5.9). How it was modelled can be seenis shown in figure 5.8 below. The head model was used to show a “normal” head. The helmet is tobe designed to fit all heads, with space for fastening of the clamps. I used a male head because they are usually bigger compared to female heads. For females, the idea is that the clamps should be adjustable,enough to fit both men and women.
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Figure 5.10 Figure 5.11
Then, a solid model of half the helmet was made by extruding from the drawn sketch and by making another sketch to show where to cut away material from the back.
Figure 5.12
Then I made a thin shell structure about 4mm thick which was 1mm less than in my previous prototype, and that helmet was usable. However, a lighter helmet is wanted. On top of this structure, the magnet fastening ring was made as a part of the model since I wanted to test this as opposed to the slider used on the helmet from the previous thesis. The advantage of this design is that it moved the end point of the robot arm closer to the ro- tational point. The fastener was made as thin as possible, extruded by about 1mm up from the helmet in addition to the curvature, making it 3mm higher in the middle.
Chapter 5: Concept 23
There were also made some nut shaped holes in order to enable nuts to be glued into place to make the clamps adjustable. If this does not work, the slider can be reintroduced in a later model. There were also made some nut shaped holes so that nuts can be glued into place to make the clamps
Figure 5.13
The magnet holding Ring on the top does not have the correct curvature com- pared with the old end-piece, as I didn’t have access to equipment to measure the curvature. But, I have easily changeable parameters, which make it possible to change these if needed later. I have tried making a magnet ring that fits the old en- dpiece by measuring the old helmet with a ruler, but I couldn’t test it, thus it can not be determined if it actually fits.
The testing of this will be discussed further in chapter 6. but the finished product can be seen below.
Figure 5.14 Figure 5.15
Chapter 6
Testing
Because of the Corona-virus situation, I was not able to test my solutions on many different people. I also needed a way to test without access to the campus.
6.1 Testing the MCU
As stated earlier, during my specialization project I got to test the MCU at Firda Physmed, This was described in my specialization project, and was a kind of Ex- patience prototyping where I got to test how it feels to use the old solution.
The MCU can only move within one degree of freedom at a time, therefore I will describe each movement separately.
Fastening of the apparatus
"Pads" being screwed to put pressure on the head felt OK, andwas not particularly uncomfortable. However, it was hard for the physiotherapist to know wether it is uncomfortable for me or if he could fasten it harder. Some patients might have a lower tolerance for discomfort, or feel uncomfortable because of the clamping.
With the apparatus fastened to my head, I could feel that it was a little loose, both because it was not clamped tight enough to "fit like a glove" and because the skin of my head slides around on the skull.
Bending the head forward/backward
Bending the head forward and backward is fine in this apparatus, however when doing it too fast, a momentum arises which can become uncomfortable with neck pains.
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Bending the head sideways
The same issues applies as when bending forwards and backward, it felt fine, the same momentum when stopping if I am doing it too fast. The apparatus sits a little better when doing this movement, but not by much.
Rotating the head from side to side
As stated earlier, the designs had to be tested by me due to the Coronavirus situ- ation. A colleague helped me by holding the helmet so that I could feel the res- istance and how well it fitted when an outside force was exerted in different dir- ections to my head. I nade sure that the force applied was more than that of the Robot arms approximately 3.5 kg of force. As a kind of a stress test.
6.1.1 How designs are Tested
As stated earlier, the designs is to be tested by me due to the Coronavirus situation.
I am going to have my roommate help me by holding it so that I can feel the resistance and how well it fits when applying force in different directions on just my head and not in my hands. Possibly also by fastening the helmet to something if I can find something to fasten it with. I will make sure that the force applied is more than that of the Robot arms approximately 3.5 kg of force. As a kind of a stress test.
How designs compare to old designs and solutions.
I will be comparing the design by how I feel that they are on the head, focusing on how comfortable they are when applying force. And checking slippage and if the feel sturdy or not. Also, I will be considering how long they take to fasten. I have described how some of the design works in the previous work section, but here I will give each attribute values and then compare them to my solution.
First prototype
Firstly, the sets of my design are the shell structure that were 3D printed from my first 3D printed prototype. I found that this solution was a sturdy solution as the shell was thicker than in the helmet from the previous master student. This I learned by adding the four clamps and then putting it onto my head, then ap- plying force. With the 5mm shell made of PLA plastic, there was no noticeable deformation when a force was applied in the direction in which it was supposed to be used. Itherefore chose to continue with this thickness, but still try to make it thinner to see if I could further reduce the weight.
Chapter 6: Testing 27
The second set that was tested in the first prototype was adding and position- ing clamps to not align with the center of the head. Even though the clamps in this prototype was not optimally placed, this solution actually worked better than expected, there was almost no slippage when applying torsion force.
The last set i decided to test is the magnetic connection, this was tested by us- ing the old model from a previous master thesis, which lacked some magnets, but as it worked fine with those missing magnets and the previous master states that it is good, i chose too go forward with it for the next prototype based on both my test and the information from the previous thesis.
The final prototype
Figure 6.1 Figure 6.2
Above, there are depictions of this prototype finished with clamps installed and how it sits on the head, i failed to account for the threads, so it was a little to small for me.
This was supposed to be just the next step in a series of prototypes, but while designing it, NTNU was closed down due to the COVID-19 outbreak. I was com- pletely locked out of school for several months. I was later given access to printers under strict conditions, but I did not have time to make anymore prototypes.
I made the shell part of this prototype 1mm thinner to test if it was still strong enough. The advantage of this would be a lighter product. A lighter helmet gives more opportunity to add resistance in the robot arm. The resulted shell structure was sturdy and showed about no deformations when applying force in the needed directions (rotational, forward, backward and sideways).
I added the last two clamps to this structure for the intended testing. I also added some nuts with threads, so that the length of the clamps could be adjusted. Fasten-
28 : Master thesis in product development
ing the clamps this way with six points of contact worked greatly, with almost no slippage. However, I failed to consider that the clamps weren’t threaded all the way. Terefore the helmet became smaller and wouldn’t fit all heads as wanted.
However, this can be fixed by either making a larger shell structure as prototype 1, or using clamps that are threaded all the way. even though the helmet didn’t fit as intended it wass still possible to test.
The Prototype is somewhat uncomfortable to wear, the reason for this is that i used bike brakes as clamps to test, these should be switched out for softer clamps that are designed for heads, like those fastened to the MCU.
How results compare with requirements
Below there is a table comparing the different solutions. The different attributes have been rated on a scale from 1 to 5, where 5 is good, and 1 is bad. As can bee
Model\Requirement Comfort Easy to Use Looseness Weight overall
ETTO helmet 5 3 3 1 12
Inflateable pads in 3D print 4 3 4 3 14
first prototype 3 4 5 4 16
Final prototype 3 4 5 5 17
seen in this table the new concept is considered to be an improvement to the old solutions. with the final prototype getting an overal score of seventeen. While the ETTO only got 12 and the 3D-printed helmet with inflateable pads got a score of 14. (The weaknesses that led to these scores are mentioned in chapter 5)
Testing of magnetic connection
Ideally, the magnetic connection should be tested to see if it was good enough or needed improvements. However the previous master student found it to function satisfactory. I have therefore not focused on improving this part, but it needs to be verified.
6.2 The optimal test setup
Since I was not be able to test properly, I am describing a way to do the testing that would have been done with access to campus. A satisfactory test setup gives
Chapter 6: Testing 29
concrete and measurable results, relevant for what we want to test. Als the tests should be reproducible. Since we are testing an apparatus that are going to be used on humans, we would need several test persons to confirm that the product fit a larger amount of people and performs with a reasonable consistency. Comfort would be tested by having subjects sit in the robot arm chair, and by using the program from the previous master thesis, make them move their head in different directions, and then ask them predetermined questions:
• 1. Can you rate how much you felt like the helmet has holding your head in place on a scale from one to ten?
• 2. Did you feel any pain? If so, can you rate it on a scale from one to ten?
• 3. How would you rate the overall experience on a scale from one to ten?
User friendliness can be tested by testing how long it takes to mount the fasten- ing mechanism. It would also be useful to check if a person not familiar with the mechanism can understand how to fasten it.
Function is somehow checked by the previous questions but we would need a completely objective way of testing this. One way to do this is to have a person sit completely still, then apply a set force, then measure how much displacement there is both during the application of the force, and after. This method will give informationon how well the head is fastened with the different solutions.
Distance from the end defector to center of rotation is somewhat tricky since it’s hard to find the center of rotation for different persons. However, if we meas- ure from end effector to shoulder for each subject, for each model, the shorter distances will correlate with a shorter distance to end effector.
Testing the magnetic connection
To test the magnetic connector, I would measure how much force it would take to overcome the magnetic forces. Both rotational and directional. This would be compared with the amount of force that can be applied from the robot arm. A solution that can “hold back” the forces from the robot arm, but be released by hand if necessary is the most desirable.
Chapter 7
Conclusion
After Testing all the solutions myself, I have arrived at a conclusion that my new solution for fastening the head with the robotarm does meet the goal set for this project. However, the prototype is not perfect and can still be improved. The reason for this is that in march we were no longer given access to campus, and after a couple of months we were given very limited access. This has made it so that I have not been able to make as many prototypes as I wanted. NTNU’s red tape for getting a prototype 3D-printed made it so that the latest version wasn’t ready before the late stages of the project. I also never got back access to the robot arm itself, so I had to find alternate solutions for testing, and the magnetic con- nection has not been tested with the actual robot arm. Therefore I have trusted earlier theses that it is good enough, and rather made a Solidworks with easily changeable parameters so that when available it is easy to make it fit.
In regards to the helmet, I found that the six-clamp solution worked better than previous solutions, and even though I am not a physiotherapist, I believe it is good enough to test on patients once the software part of the project is ready.
The clamps was however not threaded all the way in, which made the helmet too small for some people. Fastening the clamps with nuts works great as it is possible to adjust the length of the clamps, and they can be screwed in from the outside of the helmet.
The shell structure Is sturdy enough as it has almost zero deformations when being tested. It could be made a little larger if one does not find a solution with threaded clamps, or if new clamps are larger.
7.1 suggestion going forward
For the helmet solution i came up with in this thesis, i would suggest adjusting it to the latest insight from the last prototype
31
32 : Master thesis in product development
• increasing the circumference, or threading the clamps all the way.
• getting some better clamps, (more comfortable)
• adjusting the magnetic connection to fit (if it doesn’t)
• Testing it on more subjects to see how they react to it and how it feels For the rest of the project I recommend getting someone to finish the programming part of the project so that this solution finally can be tested on patients. Also looking at the requirements can provide some cool ideas for what to include in later projects.
Bibliography
[1] Nakkesleng - nhi.no, https : / / nhi . no / sykdommer / hjernenervesystem / rygg-og-nakke-sykdommer/nakkesleng/, (Accessed on 12/04/2019).
[2] Mcu - the complete system for neck pain rehabilitation | bte rehab equipment, https : / / www . btetechnologies . com / rehabilitation / mcu/, (Accessed on 07/08/2020).
[3] Products - golden therapy equipment, llc, http : / / www . kirkgolden . com / products/, (Accessed on 07/09/2020).
[4] A stewart platform. the base and platform joints are meant to be... | down- load scientific diagram, https : / / www . researchgate . net / figure / A - Stewart- platform- The- base- and- platform- joints- are- meant- to- be-universal-and-spherical_fig1_260226090, (Accessed on 07/09/2020).
[5] Ipanema - cable-driven robot for intralogistics, https : / / www . nanowerk . com/news2/robotics/newsid=34981.php, (Accessed on 07/09/2020).
[6] Https://www.franka.de/technology,https://www.franka.de/technology, (Accessed on 07/09/2020).
[7] P. A. Brennan, V. Mahadevan and B. T. Evans,Clinical head and neck anatomy for surgeons. CRC Press, 2015.
[8] Cervical instability - physiopedia,https://www.physio-pedia.com/Cervical_
Instability, (Accessed on 07/01/2020).
[9] L. Barnsley, S. Lord and N. Bogduk, ‘Whiplash injury’,Pain, vol. 58, no. 3, pp. 283–307, 1994.
[10] Whiplash - neck injury - welcome back clinic - mri and pain management centre, https://www.welcomebackclinic.com/blog/Whiplash--- Neck- Injury.htm, (Accessed on 07/09/2020).
[11] Whiplash - nhs,https://www.nhs.uk/conditions/whiplash/, (Accessed on 07/02/2020).
[12] J.-H. Lee, S.-J. Shin and C. Istook, ‘Analysis of human head shapes in the united states’,International journal of human ecology, vol. 7, Jan. 2006.
[13] K. Ulrich and S. Eppinger,Product design and development, product design and development, 2012.
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[14] J. Blindheim, C. W. Elverum, T. Welo and M. Steinert, ‘Concept evaluation in new product development’,Journal of Engineering, Design and Technology, 2020.
[15] V. P. Seidel and S. K. Fixson, ‘Adopting design thinking in novice multidiscip- linary teams: The application and limits of design methods and reflexive practices’,Journal of Product Innovation Management, vol. 30, pp. 19–33, 2013.
[16] T. Brown,Design for change, 2009.
[17] C. W. Elverum, T. Welo and S. Tronvoll, ‘Prototyping in new product de- velopment: Strategy considerations’,Procedia CIRP, vol. 50, pp. 117–122, 2016.
[18] M. Buchenau and J. F. Suri, ‘Experience prototyping’, inProceedings of the 3rd conference on Designing interactive systems: processes, practices, methods, and techniques, 2000, pp. 424–433.
[19] C. W. Elverum,Lecture in apd - 11.10.19 - agile and set-based development.pdf, https://ntnu.blackboard.com/bbcswebdav/pid-803769-dt-content- rid-23158037_1/courses/194_TMM4280_1_2019_H_1/APD, (Accessed on 12/08/2019), 2019.
Appendix A
Additional Material
In the following pages i have included my specialization project to which i refer sometimes in the thesis.
35
Summary
This is a specialization project meant to be a preparatory project for the master thesis. it is done throughout the autumn of 2019. The project is about a apparatus meant to help rehabilitate patients after whiplash injuries. this is a continuation of previous projects and master theses. all of these projects is in collaboration with Firda Physical Medical Center.
which is a specialist center on neck injuries.
During this project I have first looked at what Whiplash is and how it is normally treated.
thereafter I have looked at previous work, and took a trip to Firda to learn more, which gave me insights into the requirements of the problem. I have tested those previous so- lutions I had access too, and I the end I discuss possible improvements, and where to go forward.
I will also talk about different product development methods that I in some way use through this project or want to use during the master thesis
i
Preface
This is a specialization project written in preparation of the master thesis which is to be written next spring. in this project i will look at previous solutions, talk about what Firda Physical Medical Center wants, and talk a little aboutt he theory of productdevelopment.
Also it can be good to note that the referencing in latex stopped working for some reason, therefore if a citation is dona a little differently, you can find the source in appendix.
ii
Table of Contents
Summary i
Preface ii
Table of Contents iv
List of Tables v
List of Figures vii
Abbreviations viii
1 Introduction 1
1.1 Background . . . . 1 1.2 Problem description . . . . 2 1.3 Agenda . . . . 2
2 Previous Work 3
2.1 Multi Cervical Unit . . . . 3 2.2 Stewart plattform . . . . 3 2.3 MASNAK . . . . 4 2.4 Cable robot . . . . 5 2.5 Robot arm . . . . 6 2.5.1 controller . . . . 6 2.5.2 interface . . . . 6 2.6 Helmet and mounting mechanism . . . . 8 2.7 Chair . . . . 9
3 Basic Theory 11
3.1 The anatomy of the neck . . . . 11
3.2 Whiplash . . . . 12
3.2.1 Treatment . . . . 12
iii
3.3 Robotics . . . . 13
4 Methods 15
4.1 Product Development . . . . 15 4.2 Prototyping . . . . 15 4.2.1 Set-based design . . . . 16 4.3 Testing . . . . 17 4.3.1 Multi cervical Unit . . . . 17 4.3.2 Helmet from previous master thesis . . . . 18 4.3.3 Robot arm . . . . 19 4.3.4 Chair . . . . 19
5 Requirements 21
5.1 meeting with Firda . . . . 21
6 New Concepts 23
6.1 Possible improvements . . . . 23 6.1.1 Helmet . . . . 23 6.1.2 Chair . . . . 26
7 project conlusion 27
7.1 Going forward . . . . 27
Bibliography 28
Appendix 31
7.2 citations that for some reason does not work . . . . 31
iv
List of Tables
v
vi
List of Figures
2.1 a drawing showing a Stewart platform . . . . 4 2.2 Picture of the MCU in use . . . . 5 2.3 A model of the MASNAK . . . . 5 2.4 The Franka Panda robotarm . . . . 6 2.5 User selection page . . . . 7 2.6 Program creator page . . . . 7 2.7 Excercise creation page . . . . 8 2.8 A picture of the magnetic connection . . . . 9 3.1 Overview of the neck . . . . 11 3.2 A figure showing the different jolts that can cause a whiplash injury (WBC) 12 3.3 The Davinci Robot daV (a) . . . . 13 4.1 A model of the philosophy behind set-based design Elverum (2019) . . . 17 4.2 A picture of the helmet showing the slider . . . . 18 4.3 A picture of the chair . . . . 19 6.1 Drawing of how the clamps are placed . . . . 24 6.2 Drawing of how the clamps can be adjustable . . . . 24 6.3 Cardboard prototype of clamps . . . . 25 6.4 A picture of the cardboard prototype on my head . . . . 25
vii
Abbreviations
MCU = Multi Cervical Unit
Firda Physical Medical Center = Firda physmed DOF = Degrees of freedom
NTNU = The Norwegian University of Science and Technology NPD = New Product Development
viii
Chapter 1
Introduction
This project is a continuation of previous master theses and specialization projects. it aims to continue the work that has been put into developing a machine for rehabilitation on whiplash patients. this project is a preparatory project that is meant to continue into a master thesis in the spring of 2020.
1.1 Background
Whiplash injuries are a common problem after both sporting and car accidents, it is esti- mated that about 4000 Norwegians suffer from symptoms after car and sporting accidents in Norway, Car accidents and sports accidents are the most common but not the only way these injuries happened. Whiplash is a form of injury that in worst-case scenarios can have life long effects. about 90 percent of people whit whiplash injuries have no symptoms af- ter 6 months, which means that about 400 people a year get long-lasting issues with their neck. (NHI.NO)
Today’s solution for rehabilitation of neck injuries like this is not good enough accord- ing to Firda Physical Medical Center(Firda Physmed). Firda Physmed is one of the few specialists centers on neck trauma in Norway. their physiotherapists want functionalities in the rehabilitation apparatus that their current apparatus don’t meet. Therefore they have contacted The Norwegian University of Science and Technology (NTNU) about a partner- ship that started in 2014.
After this partnership started, several projects and master theses have been written on the subject, There have been several ideas for how the wishes of Firda Physmed can be met, and after a couple of concepts, the last couple of projects have focused on a robot arm concept. the robot arm seems to be a good solution, but there are still some issues that have to be resolved.
1
Chapter 1. Introduction
1.2 Problem description
The problem to be solved is that today’s solution for rehabilitation of whiplash injured patients need rehabilitation, but the current solution, the multi cervical unit, does not meet the demands of the physiotherapist treating these patients. a better solution is needed, and a robot-arm concept has been worked on, but still have some issues mechanically and on the software side,
1.3 Agenda
The goal of this project is to improve on previous solutions, especially in the mechanical part of the robot, in this project, I am focusing on requirements, and knowledge about how the machine works. and look at decisions that have been made earlier, and test if I agree with them or can improve on them.
The first chapters will look at the theory and what has been done earlier. after that test- ing and ideas for improvements will be introduced. and in the end some discussion about where to go from there.
2
Chapter 2
Previous Work
2.1 Multi Cervical Unit
The Multi Cervical Unit (MCU) is the solution used by Firda physmed Today and is ac- cording to Firda Physmed, the best available system on the market today. however this apparatus does not meet the needs and/or wants of the physiotherapists at Firda physmed.
The chair itself has a belt system that helps to keep the body in the right position. these belts go across your shoulder and hold them tight to the chair. this system works in a satisfactory way.
2.2 Stewart plattform
The first Concept for and improved rehabilitation was developed in the master thesis by Kristoffer Bjørnerud Slattsveen and Sondre Frantsen Tolo, in 2015. One of these concepts is the Stewart platform,
3
Chapter 2. Previous Work
The Stewart system itself is a platform with six prismatic cylinders which can be pushed up and down, all connections are done with universal joints, a Figure depicting the platform can be seen to the left, an item placed on the top plate of this platform can be moved in all the six degrees of direction(DOF). because of this, some also call this platform a 6-DOF platform or a six-axis platform.
Even though this solution seemed promising and work were continued with the project of Ole Jacob Berg and Øystein Kavle Sunde in autumn 2015.
they decided to forego the Stewart plat- form. the main arguments for this was uncertainty about the robot technical and safety for the patients. they also found that the Stewart platform was problematic with large movements with both the joints and the fastening of the head.
Figure 2.1:a drawing showing a Stewart platform
2.3 MASNAK
After deciding that the Stweart platform was not good enough berg and Sunde continued with the MASNAK concept, it is a multi-joint mechanism with a parallel structure. this solution has four linear actuators that work passively against the movement of the patient.
4
2.4 Cable robot
Figure 2.2:Picture of the MCU in use
2.4 Cable robot
Gælok and strand were in their master thesis for 2017 supposed to continue with the MAS- NAK, but after talking with Firda Physmed, they decided that its inability to move in all degrees of freedom wasn’t good enough, Therefore they decided to continue with a cable robot concept.
The cable robot is a robot based on ca- bles attached to winches, a picture of this can be seen to the left. in this concept, the number of degrees of freedom can be controlled by the number of cables.
the winches are connected to a computer that can control the cable lengths or re- sistance in the winches.
Figure 2.3:A model of the MASNAK
The Cable robot was abandoned after talking to a professor at the Fraunhofer Institute for Manufacturing Engineering and Automation in Germany. They learned that the actuators were too expensive and that getting the precision needed was very hard, and with no one with experience in the field, and some uncertainties about medical safety. The cable robot concept was abandoned.
5
Chapter 2. Previous Work
2.5 Robot arm
In their thesis, Gælok and strand landed on the Robot arm as the concept of choice, And this is the current solution. They went with a Robot arm called the Panda robot and it is made by Franka. This is a robot arm that has a feedback system based on torque sensors.
the thought behind this is that the robot arm will act against the patients’ movement, while the amount of resistance can be adjusted.
The robot arm is a common sight, espe- cially in industrial uses. and is also be- coming a more common sight in medical uses, and in uses where they are work- ing in collaboration with humans. To the left, you can see the Panda robot that was chosen, this robot was chosen because it had ”7” degrees of freedom, (these robots are said to have an extra degree of freedom, but actually has one extra joint to avoid singularities which can appear in a robot with one less joint). They also went with this Robot due to its price, that it has a precision of 0.1mm. and that it, according to its producer, can be guided with almost no resistance.
Figure 2.4:The Franka Panda robotarm
2.5.1 controller
In the previous thesis by Ove Baardsgard and Kia Brekke, A controller for this Robot arm has been developed. Their controller is a controller in the Cartesian space with very low resistance. The force controller uses a velocity control based on the pseudo-inverse method from the Eigen library, a method that uses the invert jacobian matrix gathered from libfranka. this is used to transform Cartesian velocities to joint velocities.
They also developed a method to Constrain the Robot to a pre-recorded path. this com- bined with the force controller made the Robot easy to move through a prerecorded path.
Another thing that was done was to apply a smooth resistance when the joints approached their limits.
2.5.2 interface
Baardsgaard and Brekke also developed an interface that links the user to the robot. this interface lets the user record movements and constrain movements. Below there are 3 pictures shown as examples of how the graphical interface looks.
6
2.5 Robot arm interface 1.PNG
Figure 2.5:User selection page
interface 2.PNG
Figure 2.6:Program creator page
7
Chapter 2. Previous Work
interface 5.PNG
Figure 2.7:Excercise creation page
2.6 Helmet and mounting mechanism
In the first theses, the idea was to have ETTO, an alpine helmet creator make something specifically from this task, but even though Etto was excited about the project, they didn’t have the resources for it and it was decided that this solution would be too expensive, but they recommended one of their alpine helmets, which was customized by Brattgjerd in his specialization project in 2017 this solution proved to be too heavy and loose, so Baards- gaard and Brekke decided to improve on this concept and 3D printed their own solution and tested it, which is where we are today.
8
2.7 Chair
The helmet has a magnetic connection, one of the pros with this solution is that the helmet itself detaches easily, this makes the Robot safer because if the robot suddenly moves, the helmet would detach. This connection is strong if you pull it straight down from the arm, but if you pull it skewed it will easily be removed. The magnetic connection also enables the possibility of adding different end defectors quickly, which adds the opportunity of having differ- ently sized helmets.
Figure 2.8:A picture of the magnetic connection
2.7 Chair
There has been looked at several solutions for this some of which is solutions where the patient can be standing up, or even walking. The current solution is a chair and robot mount together, where the chair is a chair with belts to hold the person in place. the chair is seen as the best solution because it gives a more consistent posture, while other solutions allows patients to ”cheat” to make the exercises lighter, This is harder to do when sitting down.
9
Chapter 2. Previous Work
10
Chapter 3
Basic Theory
To know more about how the different solutions compare, it is important to know some basic theory about both the neck and whiplash injuries, and how these injuries are treated.
3.1 The anatomy of the neck
The neck is one of the more complex parts of the body, it is both movable in a lot of di- rections, (The neck provides the Head with 6 degrees of freedom) and also contains vital Organs Like the spinal cord, blood vessels to the brain and nerves.Brennan et al. (2015) Because these are so vital to Protect, torn muscles and ligaments do not heal in the same way as in the rest of the body
The cervical spine(The spine in the neck region) is made up of 7 vertebrae, usu- ally refereed to as C!-C7, where the two on the top C1 and C2 are highly special- ized and are given unique names, Atlas and Axis, The joint between these verte- brae iare for example responsible for 60 percent of the rotation. These two dif- fer from the next five, as the next five are more classic vertebrae.(physiopedia)
Figure 3.1:Overview of the neck
11
Chapter 3. Basic Theory
3.2 Whiplash
The definition of a whiplash injury is controversial. The essential elements are that the injury takes place in a motor vehicle accident and that the head is subject to acceleration forces that result in bending of the neck. Barnsley et al. (1994) however in this project I will be using whiplash as a term for all whiplash related accidents, even those not happen- ing in motor accidents.
Figure 3.2:A figure showing the different jolts that can cause a whiplash injury (WBC)
