Thrust force synthesis-based motion control for a voice-coil actuator on a reciprocating rig with lumped disturbing-force compensation

Voice-coil actuators (VCAs) are widely applied to reciprocating rigs in tribological testing owing to their fast response. This paper addresses the motion-control problem of a VCA-driven reciprocating rig and proposes a thrust-force-synthesis (TFS) control method to improve reference-tracking accuracy. First, a mathematical model of the rig – including friction-load dynamics – is established. Next, the TFS framework is detailed, covering thrust-force synthesizer design and lumped disturbing-force estimation. Stability analysis and simulations are presented, followed by deployment on a DSP-based prototype. Experimental results demonstrate significant improvements in tracking accuracy and phase-lag suppression compared with conventional PI control. In addition, chattering effect led by sliding mode control in this case can be eliminated by using TFS control method. • Introduces thrust force synthesis based control treating VCA thrust as a virtual input. • Develops a reduced-order observer that estimates lumped disturbing forces online. • Ensures finite-time convergence and rigorously proves closed-loop stability. • Simulations cut tracking error by 96 % versus conventional PI control. • Chattering effect given by sliding mode control is eliminated in the proposed control scheme.