Nonsingular practical predefined-time control of multi-joint manipulators with input quantization and disturbance observer

Balancing the rapid control response and the prevention of actuator fatigue, particularly in scenarios involving a large dynamic range, poses a significant challenge. To mitigate frequent actuator start-stop cycles or acceleration-deceleration while ensuring control performance and safety, a nonsingular practical predefined-time control of manipulators with input quantization and a disturbance observer is proposed. A practical predefined-time disturbance observer is developed, which can deal with disturbances with unknown bounds. Subsequently, by adopting logarithmic input quantization, a balance is achieved between rapid control response and the preservation of input data characteristics, particularly in scenarios with a large dynamic range. The density of the logarithmic input quantization is finite. It ensures the accuracy and efficiency of input quantization by preserving the characteristics of the input data, especially in cases with a large dynamic range. Finally, the proposed method is verified using multi-joint manipulators and demonstrates good performance. It enhances convergence speed and disturbance rejection capabilities compared with predefined-time control utilizing linear input quantization.