Motion Control Systems

Response Dynamics engineers work closely with in-house engineering teams to improve the performance of many motion control devices such as auto focus systems and X-Y stages as well as more complex, highly coupled gantry stages.  These improvements ultimately increase the throughput capabilities of the system. 

We are able to perform the standard time domain analysis of step response performance as well as frequency domain analysis of the system transfer function.  Frequency analysis of both the closed-loop and open-loop transfer functions allows us to better determine the cause of any performance limiting issues that are present in a system.

In many devices with feedback control, such as X-Y stages, throughput performance is limited by vibration modes of the system with natural frequencies outside of the desired system bandwidth.  These vibration modes limit the magnitude of the feedback gains thereby reducing the system bandwidth and speed capabilities.  We often perform modal analysis testing along with closed loop controller analysis to identify the system dynamics that are limiting performance.  We then recommend mechanical changes and/or control loop changes to improve system performance.

Magnitude and Phase of Open-Loop Transfer Function Showing Gain and Phase Margins

Closed-Loop Transfer Function Showing Effect of Increased Gains on Secondary Mode