Adaptive Safety-Based Tracking Control for Uncertain Robotic Systems With Input–Output Constraints: A Neural Network-Based Augmented High-Order Control Barrier Function Approach

This article investigates the trajectory tracking control of uncertain robotic systems with limited control torque input bounds and joint position constraints. A novel neural network-based augmented high-order control barrier function (NN-AHoCBF) is proposed to facilitate the tracking control strategy of uncertain robotic systems with input-output constraints, where the neural network (NN) is used to estimate uncertainties in the robotic system dynamics, and the bounds of NN approximation errors and NN weights are adapted in the high-order time derivative of the HoCBFs. The NN-AHoCBF is then derivated with a series of time-varying functions, and auxiliary systems are constructed to guarantee the time-varying functions to be HoCBFs. In this way, the control input of the robotic system is relaxed by adjusting the time-varying functions through the inputs of auxiliary systems in NN-AHoCBF barrier conditions. Also, the sufficient condition for the NN-AHoCBF is provided to adaptively ensure system safety. The adaptive safety-based tracking control method is designed based on NN-AHoCBF in quadratic program (QP) framework, which can not only satisfy input-output constraints simultaneously, but also achieve good robustness and tracking performance. A simulation example is performed on a two-DOF robotic mainpulator to verify the effectiveness of the developed controller.