Low-cost precision motion control for industrial digital microscopy

This paper presents a reliable but low-cost way for industrial digital microscopy to implement μm-level precision of X/Y stage motion control. Other than the prevailing designs using stepper motors with open-loop control algorithms, the proposed method uses DC motors with closed-loop sliding mode control (SMC) to save the cost and allow a smooth switching between manual and motorized mode for stage movement. Boundary layer (saturator) method is then applied to alleviate the chattering cause by SMC, and its accuracy loss is completely eliminated by a simple position fine-tune trick to limit the error within ±2 μm. Comparing with the main stream μm-level industrial microscopies with stepper motors, the proposed solution achieves similar performance with almost half costs.