The Development of Nonlinear Model Reference PID Controller for a bipedal robot

This paper develops a new concept of a Nonlinear Model Reference PID controller for a biped robot with seven degrees of freedom. The controller consists of five second order differential equations, each in terms of the angle error of a single joint from the designed trajectory. The coefficients of each differential equation are specifiable giving the ability to specify the behavior of the biped in the presence of disturbances. Simulations are presented that show the ability of the biped robot with the Nonlinear Model Reference PID (NMRPID) controller to follow the designed trajectory in the presence of disturbances. From the experiments, NMRPID controller can reduce the errors of the trajectory when using the traditional PID controller from ±1.97 radians to ±0.0137 radians with the same gains.