Pneumatic Actuator Control Input for Friction Compensation
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Solution Overview
Problem
Pneumatic cylinders face challenges in achieving high-accuracy position control due to nonlinearities and susceptibility to frictional forces, making it difficult to implement conventional PID-based methods effectively in robots and mechatronic equipment.
Innovation Solution
A control input generating device and method that includes first and second control input generation functions, along with an output generation function, to generate control inputs based on error and velocity, compensating for nonlinear friction and reducing overshoot, using equations to calculate gains and sampling steps for precise actuator control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional PID-based control methods are used for pneumatic cylinders, then the control system is simple and easy to implement, but positioning accuracy is inferior and micron-level motion control cannot be achieved
Solution Approach 1:
The patent changes the control parameters by introducing a compensation signal that varies with the natural frequency of the feedback control system. This compensation signal is added to the main control signal to adjust the system's response characteristics and improve positioning accuracy without fundamentally changing the control architecture
Solution Approach 2:
The patent introduces a compensation signal as an intermediary element that mediates between the main control signal and the pneumatic cylinder actuator. This compensation signal specifically addresses the effects of maximum static friction force and system nonlinearities, enabling higher positioning accuracy while maintaining the overall simplicity of the control system
2Manufacturing precision
If the natural frequency of the feedback control system is used to adjust the compensation signal, then positioning accuracy of approximately 20 nm can be achieved, but the method cannot be adopted for actual robots and mechatronic equipment where natural frequency varies
Solution Approach 1:
The patent implements a self-adjusting mechanism where the compensation signal is automatically tuned based on the actual natural frequency of the feedback control system. The system measures or estimates its own natural frequency and uses this information to adjust the compensation parameters, eliminating the need for manual calibration and enabling deployment in actual robots and mechatronic equipment with varying operating conditions
3Manufacturing precision
If pulse width is adjusted for positioning control, then positioning accuracy of approximately 50 nm can be achieved, but the method requires known pulse width parameters that vary with system conditions
Solution Approach 1:
The patent transitions from static pulse width parameters to dynamic compensation signals that adapt in real-time based on the system's natural frequency and operating conditions. The compensation signal is continuously adjusted to maintain optimal positioning performance across varying loads, temperatures, and system states, eliminating the need for repeated parameter calibration
Data Source
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AI summary
[Object] To provide a control input generating device that generates a control input for controlling a pneumatic actuator with high accuracy. [Solution] A control input generating device configured to generate a control input for controlling a pneumatic actuator includes a first control input generation function, a second control input generation function, and an output generation function. The first control input generation function is configured to generate a first control input when an error exists between a target value and a controlled variable. The second control input generation function is configured to, when the controlled variable is varying with time, generate a second control input that increases as the error between the target value and the controlled variable decreases. The output generation function is configured to generate the control input based on the first control input and the second control input. Using the generated control input for controlling the pneumatic actuator can improve the actuator's responsiveness near the target value and reduce overshoot relative to the target value, thereby enhancing the accuracy of operating the pneumatic actuator to reach the target value. This can even prevent overshoot relative to the target value.