Design of a Canine Prosthesis for Front Limb Deformities

The current canine prosthesis market is catered towards dogs with amputations. Due to the variations in limb deformities, there is yet to be a customizable solution. Instead, the production of prostheses for deformities occurs on a ‘case-by-case’ basis and the products are tailored to a specific user. The goal of this project was to design and fabricate a low cost device that would increase mobility and stabilize the gait of the canine user. Our project focused on a dachshund with a front limb deformity to produce a device that can be customized to other canines with similar deformities. The final device was a 3D printed custom fit prosthesis

Mechanical Prosthetic Hand for Navy SEAL

Quality of Life Plus has been improving the lives of many wounded servicemen and first responders around the country. Its mission is to foster and generate innovations to aid and improve the quality of life for those injured in the line of duty. This project is the fifth iteration of designing a prosthetic hand for an active duty Navy SEAL. The first iterations have been myoelectric systems where sensors are attached to the user’s muscles to actuate the prosthetic. However, the most recent has been a purely mechanical system, and was shoulder actuated. The design was more robust, it was lightweight compared to the first iterations, and it is also waterproof. This project is made out of Titanium 6AL-4V, which offers a great strength-to-weight ratio, is robust, reliable and easy to assemble. This project took a different avenue of approach when manufacturing the prosthetic hand. The vast majority of the hand was 3D-printed using the latest technology of direct metal laser sintering. The material chosen for this device is Ti 6-4, where it was printed and donated by Lawrence Livermore National Laboratory located in Livermore, CA. Most of the hardware was made out of stainless steel and was purchased from McMaster Carr, and the Sure-Lok was obtained from a previous iteration. The prosthetic hand will include shock cord, non-flexible cable to withstand up to 200 lbs. per finger and a break cable that will interlock the fingers, palm and gantlet sub systems of the prosthetic. The device will also include a silicon sleeve with an embedded plate that will attach to the palm. The sleeve will attach via suction to the users residual and has been proven to work as he currently uses a similar device with a purely aesthetic hand. This prosthetic was designed by analyzing the Raptor Hand created by e-Nable, an organization that helps small children by creating prosthetic hands that can be easily printed and assembled. In order to actuate our prosthetic, the user will need sufficient wrist movement and strength for proper function. Since our client has full mobility of his wrist, this will be the best method. The prosthetic uses a Sure-Lok to allow the user to maintain a grip without applying any excess force. The non-flexible cable will maintain a tension that will allow the user to grip and hold heavy items over a long period of time. Once the Sure-Lok is not active, the flexible cord will spring the fingers back into the initial position. The thumb is not connected to any cables and is spring loaded to allow the user to manually place the thumb in three different positions. During the initial inspection of the titanium parts received, the team noticed that the support material was still intact and needed to be removed. This will delay the assembly and testing of the titanium prototype. The support material will be removed via Electric Discharge Machining (EDM), which is a controlled process that is used to remove metal by electric spark erosion. The electric spark is used as the cutting tool to erode the work piece to the desired surface finish. Once completed, the hand will be assembled and tested and will be sent to the client’s prosthetist to implement the silicon sleeve. Furthermore, our donor has agreed to reprint the prosthetic to allow any improvements of the design. This will be done towards the end of the summer. Several of our team members will remain in contact with the sponsor and LLNL to oversee the completion of this design

iMOVE: Development of a hybrid control interface based on sEMG and movement signals for an assistive robotic manipulator

For many people with upper limb disabilities, simple activities of daily living such as drinking, opening a door, or pushing an elevator button require the assistance of a caregiver; which reduces the independence of the individual. Assistive robotic systems controlled via human-robot interface could enable these people to perform this kind of tasks autonomously again and thereby increase their independence and quality of life. Moreover, this interface could encourage rehabilitation of motor functions because the individual would require to perform its remaining body movements and muscle activity to provide control signals. This project aims at developing a novel hybrid control interface that combines remaining movements and muscle activity of the upper body to control position and impedance of a robotic manipulator. This thesis presents a Cartesian position control system for KINOVA Gen3 robotic arm, which performs a proportional-derivative control low based to the Jacobian transpose method, that does not require inverse kinematics. A second control is proposed to change the robot’s rigidity in real-time based on measurements of muscle activity (sEMG). This control allows the user to modulate the robot’s impedance while performing a task. Moreover, it presents a body-machine interface that maps the motions of the upper body (head and shoulders) to the space of robot control signals. Its uses the principal component analysis algorithm for dimensionality reduction. The results demonstrate that combining the three methods presented above, the user can control robot positions with head and shoulders movements, while also adapting the robot’s impedance depending on its muscle activation. In the future work the performance of this system is going to be tested in patients with severe movement impairments

Optimization of Prosthetic Hands: Utilizing Modularity to Improve Grip Force, Grasp, and Versatility

It has been demonstrated that although many varieties of upper limb prosthetics exist, commercially available prosthetics are outdated and unsatisfactory. Ineffectiveness and limitations have led to some prosthesis wearers having to own multiple devices, whereas others have given up on them entirely. Even though ample research has been conducted to design and test new hand designs, the industry appears to rest in an overall stagnated state. It was proposed here, that one problem with prosthetic research is an excess of variables involved in testing, and therefore the improper application of the scientific method. It seems that each time a research team desires to test a new idea, a completely new hand and system is designed to house it. A costly and time-consuming cycle is then initiated which may lead to comparing the merits of one hand to the performance of distinct hand designs with multiple differences. Since these comparisons involve multiple variables, the results are often inconclusive and many projects end up shelved. To help advance prosthetic improvement, it seems necessary to unclog the process by lowering costs, speeding up development, and implementing an improved basis for comparison. The proposed method for achieving the first two objectives is to make use of a 3D printed hand platform. Such prosthetics are durable, inexpensive, and quick to manufacture and assemble. This allows for rapid transition from idea to prototype, and from observation to improvement. The method for improving comparison is the addition of modularity into the prosthetic. If a single hand could be reconfigured to implement different attributes and ideas, the merit of each innovation could be independently demonstrated and verified. In this research, a 3D printed hand was chosen which could accommodate configurations capable of adding adaptation as well as a resting state of partial curvature to the basic hand. The various configurations, including neither, each, and both changes were then tested in a series of experiments. These were arranged to discover the maximum weight that could be sustained while the hand attempted to maintain grasp on various bar shapes. These tests were run in two different test setups: attached to a non-amputee’s arm and suspended by clamps, in order to determine the influence introduced by the limitations of human strength and physiology. These rounds of testing successfully demonstrated that small modifications to the prosthetic could yield improvements in performance (even with a basic, low-cost hand), and that the merit of various ideas can be independently demonstrated on a singular platform

Redesigning a prosthesis for a golfer with transhumeral amputation

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Includes bibliographical references (leaves 103-106).The objective of this thesis was to determine the motions needed in a prosthesis that would enable a transhumeral amputee professional golfer, Michael Gibson, to play golf with similar dynamics to those of a two-armed golfer. Although he plays golf well using only one arm, his swings tend to have less power and are less consistent than his two-armed colleagues. Significant user testing was carried out using various prototypes with Gibson. Analysis was performed with Gibson's feedback, video comparisons of swings, and data from both motion capture and flight analysis software. Not only were differences in the dynamics of Gibson's swing and a two-armed golfer's swing studied, but the root causes of the differences were understood. It was determined that a prosthesis that enables wrist cock, forearm rotation, and slight elbow compliance would increase Gibson's golf performance.by Helen Tsai.S.M

Advancing the Underactuated Grasping Capabilities of Single Actuator Prosthetic Hands

The last decade has seen significant advancements in upper limb prosthetics, specifically in the myoelectric control and powered prosthetic hand fields, leading to more active and social lifestyles for the upper limb amputee community. Notwithstanding the improvements in complexity and control of myoelectric prosthetic hands, grasping still remains one of the greatest challenges in robotics. Upper-limb amputees continue to prefer more antiquated body-powered or powered hook terminal devices that are favored for their control simplicity, lightweight and low cost; however, these devices are nominally unsightly and lack in grasp variety. The varying drawbacks of both complex myoelectric and simple body-powered devices have led to low adoption rates for all upper limb prostheses by amputees, which includes 35% pediatric and 23% adult rejection for complex devices and 45% pediatric and 26% adult rejection for body-powered devices [1]. My research focuses on progressing the grasping capabilities of prosthetic hands driven by simple control and a single motor, to combine the dexterous functionality of the more complex hands with the intuitive control of the more simplistic body-powered devices with the goal of helping upper limb amputees return to more active and social lifestyles. Optimization of a prosthetic hand driven by a single actuator requires the optimization of many facets of the hand. This includes optimization of the finger kinematics, underactuated mechanisms, geometry, materials and performance when completing activities of daily living. In my dissertation, I will present chapters dedicated to improving these subsystems of single actuator prosthetic hands to better replicate human hand function from simple control. First, I will present a framework created to optimize precision grasping – which is nominally unstable in underactuated configurations – from a single actuator. I will then present several novel mechanisms that allow a single actuator to map to higher degree of freedom motion and multiple commonly used grasp types. I will then discuss how fingerpad geometry and materials can better grasp acquisition and frictional properties within the hand while also providing a method of fabricating lightweight custom prostheses. Last, I will analyze the results of several human subject testing studies to evaluate the optimized hands performance on activities of daily living and compared to other commercially available prosthesis