Offline tuning mechanism of joint angular controller for lower-limb exoskeleton with adaptive biogeographical-based optimization

Designing an accurate controller to overcome the nonlinearity of dynamic systems is a technical matter in control engineering, particularly for tuning parameters precisely. In this paper, mechanism proportional-integral-derivative (PID) lower limb exoskeleton (LLE) joints by adaptive biogeographical based-optimization (ABBO) presented. The defined as optimization problem and solved ABBO, which iterative algorithm inspired blending crossover operator (BLX-?). migration change proportionally growth iteration that conveys error rapid convergence narrowing searching space. Lyapunov stability theory proven LLE nonlinear systems. ABBO compared with other conventional methods step response, guaranteed it was not trapped local optima demonstrated lowest average fastest rate. tuned applied closed-loop system verify its performance prototype. experimental results PID ascertained proposed applicable gait training.