Stable Control of Single-Link Flexible-Joint Manipulator

This paper presents a novel approach for stable control of a single-link flexible-joint manipulator (SLFJM). The control objective is to stabilize the SLFJM at the straight-up equilibrium position from the straight-down equilibrium position and suppress vibration by only using position measurement. First, differential homeomorphic transformation is used to equivalently convert the original system into a new handy system. Next, the new system is divided into two parts: linear and nonlinear. The nonlinear part is considered as a virtual disturbance of the linear part. Then, the Equivalent-input-disturbance-based (EID-based) control system is designed to suppress this virtual nonlinear disturbance at the zero equilibrium point. By this way, the control objective of the original system is effectively realized. Finally, the numerical results demonstrate its validity.