Adaptive sliding manifold slope via grasped object stiffness detection with a prosthetic hand

Upper limb amputees have expressed the desire for their prosthetic hands to better adapt to the parameters of different grasped objects. In response to this need, an adaptive sliding mode controller (ASMC) is developed that has a variable-slope manifold which is dependent upon the stiffness of the grasped object. The ASMC is experimentally compared to a sliding mode controller (SMC) which has a constant manifold slope over a wide range of grasped object stiffness, ranging from an empty hand to a steel bar. Experimental results indicate that both controllers have satisfactory percent overshoot characteristics; however, the ASMC has significantly less absolute error for all experiments performed with eight different levels of grasped object stiffness. (C) 2013 Elsevier Ltd. All rights reserved.