Closed Loop Force Control of a Flexible Monolithic Prosthetic Finger

Bayoumi, Hazem; Awad, Mohammed I.; Maged, Shady A.

doi:10.1109/niles56402.2022.9942439

Cited by 1 publication

(2 citation statements)

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“…This will achieve a suitable grasping force that is comparable to what is found in the literature. Specifically, a finger’s grasping force with this mechanical setup was found to be up to 170 g [ 44 ], which is more than sufficient when compared with the 30–75 g grasping force per finger featured in [ 25 ]. Additionally, the motor achieves this while still being lightweight.…”

Section: Methodsmentioning

confidence: 99%

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An Improved Approach for Grasp Force Sensing and Control of Upper Limb Soft Robotic Prosthetics

2023

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The following research proposes a closed loop force control system, which is implemented on a soft robotic prosthetic hand. The proposed system uses a force sensing approach that does not require any sensing elements to be embedded in the prosthetic’s fingers, therefore maintaining their monolithic structural integrity, and subsequently decreasing the cost and manufacturing complexity. This is achieved by embedding an aluminum test specimen with a full bridge strain gauge circuit directly inside the actuator’s housing rather than in the finger. The location of the test specimen is precisely at the location of the critical section of the bending moment on the actuator housing due to the tension in the driving tendon. Therefore, the resulting loadcell can acquire a signal proportional to the prosthetic’s grasping force. A PI controller is implemented and tested using this force sensing approach. The experiment design includes a flexible test object, which serves to visually demonstrate the force controller’s performance through the deformation that the test object experiences. Setpoints corresponding to “light”, “medium”, and “hard” grasps were tested with pinch, tripod, and full grasps and the results of these tests are documented in this manuscript. The developed controller was found to have an accuracy of ±2%. Additionally, the deformation of the test object increased proportionally with the given grasp force setpoint, with almost no deformation during the light grasp test, slight deformation during the medium grasp test, and relatively large deformation of the test object during the hard grasp test.

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Section: Methodsmentioning

confidence: 99%

“…Fortunately, however, this small drop in accuracy is negligible for our application. Additional details regarding this sensor design and closed loop force control tests can be found in [ 44 ].…”

Section: Methodsmentioning

confidence: 99%