Lidar Mirror Positioning via Combined Open and Closed Loop Control
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Solution Overview
Problem
Control systems face challenges in optimizing bandwidth without compromising other optimization criteria, such as error minimization and disturbance suppression, while maintaining system stability.
Innovation Solution
The implementation of a combined open loop and closed loop control system that generates control signals from the desired system output, using a feed-forward path to directly derive the control signal from the desired output and account for group delays, allowing for independent control of tracking performance and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If closed-loop control is used to minimize error and suppress disturbances, then system stability is maintained, but control bandwidth is limited by stability constraints
Solution Approach 1:
The control system is segmented into two independent parts: an open-loop feedforward controller that determines tracking bandwidth without stability constraints, and a closed-loop feedback controller that ensures stability and suppresses disturbances. This segmentation allows each controller to be optimized for its specific function without compromising the other.
Solution Approach 2:
The open-loop feedforward controller performs preliminary action by generating control signals based on the desired trajectory before the closed-loop feedback controller acts. This preliminary control establishes the primary tracking performance, while the feedback controller only needs to provide minor corrections, enabling higher overall bandwidth.
2Measurement precision
If control bandwidth is increased to improve tracking performance, then tracking accuracy is improved, but system stability may be compromised
Solution Approach 1:
The control system is divided into feedforward and feedback components with distinct responsibilities. The feedforward controller handles high-bandwidth tracking without stability constraints, while the feedback controller maintains stability, allowing tracking accuracy to improve without compromising system stability.
3Reliability
If optimization focuses on error minimization and disturbance suppression, then system reliability is improved, but control bandwidth is reduced due to stability constraints
Solution Approach 1:
The control architecture segments error minimization and disturbance suppression functions into the feedback controller, while bandwidth optimization is assigned to the feedforward controller. This allows both objectives to be achieved simultaneously without the traditional trade-off.
Solution Approach 2:
The feedback controller continuously monitors system output and generates corrective signals to minimize errors and suppress disturbances. This feedback mechanism ensures reliability while the independent feedforward path maintains high bandwidth performance.
Data Source
AI summary
According to various implementations of the invention, a system for controlling a controlled device includes a lidar configured to direct at least one beam toward a target; a first controlled device, wherein the at least one beam is directed toward the target via the first controlled device; and a control system configured to control a position of the first controlled device, where the control system includes an open loop controller and a closed loop controller. The open loop controller is configured to receive a desired trajectory command signal, and generate an open loop drive signal based on the desired trajectory command signal. The closed loop controller is configured to receive an actual position signal of the first controlled device, and generate a closed loop drive signal based on the actual position signal and a control signal derived from the command signal, where the control signal accounts for group delays associated with one or more control system components. A combined drive signal is generated by combining the open loop drive signal and the closed loop drive signal. The combined drive signal is provided to control the position of the first controlled device.