A Unified Robust Motion Controller Design for Series Elastic Actuators

Abstract

Series Elastic Actuators (SEAs) have several mechanical superiorities over conventional stiff and nonback-drivable actuators, e.g., lower reflected inertia at output, greater shock tolerance, low cost force measurement, energy storage, safety, and so on. However, their applications generally suffer from performance limitations, particularly in position control, due to insufficient controller designs. This paper proposes a unified Active Disturbance Rejection (ADR) motion controller for the robust position and force control problems of SEAs by using Differential Flatness (DF) and Disturbance Observer (DOb). It can suppress not only matched but also mismatched disturbances. Robust state and control input references are systematically generated in terms of a fictitious design variable, namely differentially flat output, estimations of disturbances, and their successive time derivatives. The proposed robust motion controller improves the performance of SEAs when they suffer from internal and external disturbances, such as friction, inertia variation and external load, in real implementations. Experimental results are given to validate the proposal.

Non‐linear‐disturbance‐observer‐enhanced MPC for motion control systems with multiple disturbances

“…Remark 2: The considered system (1) is a more generalised model developed from the practical motion control systems. It is worth pointing out here that the practical motion systems from a simple one-or two-order system [17] to a complicated robot system [30][31][32] can be all regarded as one single system (1) or several cascaded systems generated by (1). Hence, the design of the MPC method for system (1) to achieve high-performance tracking is fundamental and significant for motion control systems.…”

Controller for UAV to Oppose Different Kinds of Wind in the Environment

“…Some previous relative research achievements considered the external disturbance as a lumped disturbance and proposed advance-control-theory-based controllers to reject or attenuate this lumped disturbance [15,16]. However, these external disturbances have different magnitude and frequency, so it is unreasonable to synthetically regard them as lumped disturbance.…”

A Sliding Mode Force and Position Controller Synthesis for Series Elastic Actuators

“…The position accuracy of an SEA's link may significantly deteriorate by external load and various internal disturbances, such as nonlinear frictions and hysteresis, due to its complex mechanical design. 25 To track the desired trajectory of an SEA's link with high accuracy e.g., q = q des , τ d m and τ d l should be precisely suppressed/cancelled.…”

“…Authors recently proposed a new motion controller for SEAs in ref. [25]. In this paper, an SEA's force control problem is described by a fourth-order dynamic model which suffers from matched and mismatched disturbances.…”