Smart haptic Knee Brace

Project team member(s): Julien Buist-Thuillier, Nolan Jetter, Saran Grandhe, Cyrus Xiang, Adam Blanchard

When returning to playing a sport from an injury, athletes/patients can overexert themselves, causing reinjury. This can be caused by overuse, too high of force on the injured region, or going beyond the healthy range of motion post operation. The motivating idea is that there are 3 common ways to re-injure a reconstructed ligament: overuse, too high of a force, and extension beyond safe range of motion. After ACL surgery (and many other knee operations), a brace is commonly used to stabilize the joint. It is often difficult for the patient to discern when they are overusing, putting too much force, or straining the joint in unsafe ways. In addition, after talking to PT, people’s memory of technique and depth drifts over time, resulting in patients carrying out exercises in the wrong way. This is a serious problem for both patients and PTs. Therefore, the goal is to design a haptic feedback brace that helps the patient understand the safe limit of their body and to track recovery. Since the brace is intended to be used while squatting, hopping, or performing similarly high energy activities, understanding the range of possible dynamics and impedances of the knee will be critical for ensuring the passivity of our design and the safety of the athlete/patient.

Introduction

Explain the motivation for your project in terms of the educational objectives and why your haptic device is an appropriate approach.

Background

Explain the relevant prior work in the field of haptics and provide references. These will likely be different from the references in your project proposal. Make sure to do a thorough literature search on relevant haptic devices/application.

Methods

Provide a detailed description of your project, such that another student from the class could generally re-create your project/experiment from the report if necessary. (You don't need to document every screw, but the design should be clear.) Add images and videos as needed to support the description. You can refer to downloadable drawings and code in the "Files" section (later). You should divide this section into subsections, which can vary depending on your particular project. Here is an example set of subsections:

Hardware Design and Implementation

System Analysis and Control

Demonstration / Application

Results

Describe the results, which may include qualitative responses from users at the open house.

Future Work

Describe how your system could be tested (e.g., through experiments if you have not already done so), how it can be improved, and how it might be applied.

Acknowledgments

Here you can list any individuals or groups who helped you with your project. (e.g., another student in the class, a course assistant, or an especially helpful PRL TA). Optional, so delete this section if you aren't using it.

Files

Code and drawings should be linked here. You should be able to upload these using the Attach command. If you aren't willing to share these data on a public site, please discuss with the instructor. Also, in this section include a link to a file with a list of major components and their approximate costs.

References

List the referenced literature, websites, etc. here.

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Appendix: Project Checkpoints

Checkpoint 1

These are the planned tasks for checkpoint 1:

• Finalized BOM
• Initial CAD for motor mount and capstan
• Initial prototype of motor mounted to the brace
• KiCAD Schematic

We are currently on track with our Checkpoint 1 deliverables. Securing all necessary components is a major milestone, especially given the anticipated lead times. The overall product architecture- encompassing the mechanical design, electrical layout, and feature roadmap, is well-defined. In our current timeframe, we are confident in successfully implementing both the kinesthetic and vibrotactile feedback for knee flexion and extension. Functionally, the team is prioritizing squat tracking to provide real-time biomechanical feedback.

Finalized BOM:

Along with sourcing the knee brace, we also finalized the BoM and acquired all the components for MVP. Other components are decided and order's yet to be placed. For motor selection we benchmarked the torque an average human knee exerts and finalized the motor along with gear train design. Knee safety and the right amount of torque for a good kinesthetic feedback are considered.

Initial CAD for motor mount and capstan:

With the motor selected, we got the entire initial CAD made: the gear transmission, motor mount, and capstan drive. The mechanical advantage is gained through the gear reduction ratio and the pulley diameter difference in the capstan drive.

Initial prototype of motor mount:

KiCAD Schematic:

This is the completed circuit for the MVP product.

Checkpoint 2

Here you will write a few paragraphs about what you accomplished in the project so far. Include the checkpoint goals and describe which goals were met (and how), which were not (what were the challenges?), and any change of plans for the project based on what you learned. Include images and/or drawings where appropriate.

Example Video: https://www.youtube.com/watch?v=i_aLBql4Ufo