Optimal LQ feedforward tracking with preview: Practical design for rigid body motion control

•Explicit formulas for optimal LQ feedfoward motion controllers are derived.•Key aspects of design and implementation for motion control systems are explained.•A redesign method for finite preview is proposed that preserves polynomial tracking properties.•Comparative experimental results for a motor-driven linear motion stage are presented.

For reference-tracking motion control, preview-based linear quadratic (LQ) design methods provide an effective means to balance tracking performance with available actuation capacity. This paper considers a control structure for which the optimal feedforward controller is independent of the feedback controller. In this way, explicit implementation formulas for feedforward controllers are derived that can be applied to a range of rigid-body motion systems. Key aspects of the optimal LQ solutions are identified, particularly how the choice of design weightings affect steady-state error for polynomial tracking. A redesign procedure for finite preview-time is proposed that preserves exact polynomial tracking properties and control bandwidth of the optimal solutions. Comparative experimental results are presented for a motor-driven linear motion stage.