Hand system for Open Hand
Closer look at the homemade force sensors
Feedback system to be mounted at a location based on the user's preference
Many prosthesis users today rely on visual cues to determine how much they are gripping down on an object. This can become a problem when they are wanting to grab a delicate object, such as an egg. If they grab too hard, it runs risk of cracking the egg, which is just one of many problems related to this lack of grip feedback. Open Hand is designed to provide those with prosthetic hands feedback regarding to how hard they gripping on object. Likewise, prosthesis come in all shapes and sizes, and getting one replaced or upgraded can be costly. Open Hand is designed to be an attachment to existing prosthesis, allowing owners to keep their current one but still experience improvements for a fraction of the cost.
What it does
Open Hand comes in two systems: the hand system and the feedback system. The hand system contains two force sensors, one on the thumb and one of the index finger, used to detect the applied force in the respective areas. Then, the sensor values are sent over wireless serial to the feedback system, which contains two motors, one related to each force sensor, that will run when the user is gripping an object and stops when they are not. That way, the user can receive immediate feedback regarding their grip status.
How we built it
The hand system contains of two force sensors, an XBee antenna, and an Arduino Nano. Furthermore, motors were included to give feedback to the user. In one circuit, data is gathered from forces in the user's fingertips, sent to the first Arduino, relayed over the XBees to the second Arduino, and finally routed to the motors.
Challenges we ran into
Prior to the competition, force sensors and haptic motors were ordered for use in the project. However, the shipment was delayed and the parts were not expected to arrive until after the competition. In order to solve this, force sensors were made from paper, aluminum foil, wires and tape. In the place of the haptic engines, normal DC motors were used.
Accomplishments that we're proud of
We have created a device that can truly improve the lives of certain individuals, and done so with common readily available items. Likewise, the project can be simplified even further (such as removing the wireless XBee modules), decreasing the cost of the device. We estimate that if the system were wired (which may be opted in more permanent fixtures) and using the planned force sensors and haptic motors, the entire device shouldn't cost more than $25. This whole project is something to be proud of.
What we learned
Taking on this project helped us in understanding development and design of wearable devices, especially in the medical field. Furthermore, the project improved our ability to improvise solutions to problems that may otherwise seem insurmountable.
What's next for Open Hand
Once the parts ordered for Open Hand arrive, it will be interesting to recreate the system with its intended parts. Past that, the project would need to be adapted to fit any prosthetic. Furthermore, the system at the moment only reads forces normal to the fingers. An excellent next step for Open Hand would be to add the ability to detect shear forces.