HILS Load Control Using Inverse Transfer Function Compensation
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Solution Overview
Problem
Existing HILS test systems face challenges with response lag in load systems due to actuators, leading to inaccurate real-time simulations between models and real machines.
Innovation Solution
A test system that includes a test piece, an actuator, a virtual model, a controller, a computing device, and an inverse transfer function correcting unit, which corrects signals from the virtual model using a proper inverse transfer function based on the system's transfer function, ensuring accurate real-time control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If offline correction using inverse transfer function is used, then manufacturing precision is improved, but productivity deteriorates due to iterative testing requirements
Solution Approach 1:
The system performs preliminary identification of the load device's transfer function characteristics before actual HILS testing. By pre-calculating the inverse transfer function based on identified parameters (mass, damping coefficient, stiffness), the system prepares correction data in advance, eliminating the need for iterative offline correction during testing and improving overall productivity
2Reliability
If real-time inverse transfer function correction is implemented, then reliability is improved by eliminating response lag, but device complexity increases
Solution Approach 1:
The system introduces a signal processing unit as an intermediary component between the model and load device. This unit applies the pre-calculated inverse transfer function to command signals in real-time, compensating for load device dynamics without requiring complex modifications to the load device itself or the model, thus achieving improved reliability with minimal increase in device complexity
Solution Approach 2:
The system replaces physical modification of the load device with computational correction. Instead of mechanically adjusting the load device to eliminate response lag, the system uses mathematical inversion of the transfer function to compensate for dynamics effects, substituting mechanical complexity with computational processing
3Ease of operation
If predetermined signal correction is used, then ease of operation is improved, but adaptability deteriorates as only specific signals can be corrected
Solution Approach 1:
The system identifies key parameters of the load device (mass, damping coefficient, stiffness) and uses these parameters to generate the inverse transfer function. By changing from signal-specific correction to parameter-based correction, the system achieves universal adaptability across different signal types while maintaining ease of operation through automated parameter identification and function generation
Data Source
Figure 1(a)~1(b)
Figure 2
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AI summary
To provide a test system that can eliminate a response lag of a load system caused by an actuator that actuates a test piece or the like and enable more accurate real-time simulation involving a model and a real machine. To this end, a test system 1 is provided which includes a test piece 40 as a part of a real machine that is to be tested, an actuator 30 that actuates the test piece 40, a virtual model 11 that operates in association with the test piece 40, a controller 20 that controls the actuator 30, a computing device 10 that computes the virtual model 11, and an inverse transfer function correcting unit 50 that corrects a signal from the virtual model with a proper inverse transfer function that is determined based on a transfer function of a system including communication units between the test piece 40 and the actuator 30 and between the actuator 30 and the controller 20 and a communication unit between the computing device 10 and the controller 20, and the controller 20 controls the actuator 30 based on the signal corrected by the inverse transfer function correcting unit 50.