Design and Robust Control of a 2 DOFs Lower Limb Exoskeleton

Abstract

For the past few decades, robotic exoskeletons have been the subject of extensive research in research laboratories. The level of performance and reliability of these systems has steadily increased. Today, these applications involve neuromotor rehabilitation and, more marginally, support for patients suffering from motor impairments. In this context, we designed and built a motorized exoskeleton with two degrees of freedom for the functional support of the lower limbs. The design was developed taking into account the different constraints related to the anatomy of the human being lower limb and the kinematic-static compatibility and the transparency of the structure. Elastic actuators, which combine deformable elements and conventional DC motors have been produced and associated with the mechanical structure. The electronic part was also developed to instrument and control the joints of the exoskeleton. After the modeling, we have synthesized and implemented several control approaches, namely PID and Twisting second order sliding mode. The results obtained showed the capacity of the exoskeleton to perform walking cycles and its robustness with regard to external disturbances.