This dissertation aims to investigate the effect of toe-joint on walking performance and standing stability. For walking, kinematical and dynamical studies are carried out. In the kinematical study, experimental walking data of normal subjects were collected. A kinematic index for natural walking is computed based on collected data. In the dynamical study, energy consumption, is compared in walking with toe bending and locked toe-joint states. Simulation results show that bending of toe reduced the energy consumption. Study of the standing control of biped with toe-joint is another objective of this research. A bipedal model contains an inverted pendulum as the upper body and a foot with toe-joint. The balance regulation is done using ankle strategy and ankle-toe strategy. First, effect of forcing constraints on standing balance of the biped is studied and the allowable torque bounds are computed. Then standing balance control is done by ankle strategy using PD switching and model predictive control methods. Standing balance control is fulfilled using model predictive control by implementing configuration constraints and using state feedback control based on LQR method without considering excess constraints. Simulations showed that the ankle-toe strategy has better performance and reduced the actuator demand. The stability analysis for nonlinear system is performed using concept of Lyapunov exponents. The system’s stability is investigated and domain of attraction is calculated. Results show that the toe-joint increases domain of attraction. This effect is more important especially in the case with high heel foot. Keywords : Toe-joint, kinematic index, dynamic index, forcing constraints, configuration constraints, ankle strategy, ankle-toe strategy, Lyapunov exponents, model predictive control .
