The SoftHand Pro-H: A Hybrid Body-Controlled, Electrically Powered Hand Prosthesis for Daily Living and Working

In this article, we study the feasibility of applying the SoftHand technology to a prosthetic device that is suitable for activities of daily living (ADL) and, in particular, some important objectives such as doing work, performing home chores, and participating in hobbies. These applications have specific requirements, such as high grip power; grasp versatility; ruggedness; resilience; resistance to water, dust, and temperature; durability; power autonomy; and low cost. Alternatively, factors like the multiplicity of gestures or aesthetics are less dominant. The intuitiveness of control by the user is a particularly relevant and specific objective of our work. While multiactivation-modalities prostheses use sophisticated myoelectric control to afford versatility and dexterity, most state-of-the-art work-oriented prostheses are body powered (BP). BP prostheses (BPPs) are intuitive to use, have low cost, do not require batteries or motors, and provide useful built-in, sensorless feedback to the user. In this article, we explore the possibility of realizing prosthetic systems that combine the two worlds, creating a hybrid solution that shares advantages from both, by using inputs from a shoulder harness to control an advanced 19 degrees of freedom (19 DoF), underactuated anthropomorphic, electrically powered hand. We start from an analysis of possible locations of the main components of the prosthesis (the motor, battery pack, and electronics) on the user's body. As a result of this analysis, eight configurations are isolated as possible solutions for different requirements. One of these solutions has been implemented in a functional prototype, called SoftHand Pro-H (SHPH), and used by the SoftHand Pro team in the Cybathlon 2016: Powered Arm Prosthesis Race (C-PAPR).