Average Power as an Alternative Variable for Power grip Control in Robotic Hands Without Using Force Measurements

Power grip is one of the fundamental functionalities of a robotic hand prosthesis, as it is essential for performing various activities of daily living. This study proposes the use of the average electrical power consumed by the actuators as a variable correlated with grip force in mechanisms with an effective degree of freedom equal to one. This approach enables the implementation of closed-loop grip force control schemes without the need for force sensors. To evaluate the performance of the proposed method, a five-finger underactuated robotic hand prototype was developed, along with a cascade control scheme to track an average power reference. The system was implemented in the Simulink environment of Matlab, using an Arduino Mega 2560 board for signal acquisition and actuator control. The powerforce relationship was validated using a variable stiffness device, in accordance with recommendations from a standardized protocol for evaluating the quality of robotic hand prostheses. The results show that average electrical power exhibits a stronger correlation with grip force than electric current, which has been used for similar purposes in previous studies. This work addresses the challenge of controlling grip force without force sensors, introducing a variable that has not been previously exploited for this purpose