Steering Torque Control to Eliminate Rattle Noise Pulses
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Solution Overview
Problem
Existing steering control devices generate rattle noise due to pulse noise caused by large changes in gradient at the breakpoint of the map between estimated load torque and target steering torque, especially in small signal regions.
Innovation Solution
A steering control device that includes a servo controller, an estimated load torque calculation section, and a target steering torque calculation section, which calculates a base assist command using proportional integral control to prevent large gradient changes, thereby eliminating pulse noise and reducing motor vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a map with large gradient change at breakpoint is used to improve steering feel, then steering precision is improved, but pulse noise is generated causing rattle noise
Solution Approach 1:
The patent applies preliminary action by calculating and compensating for the gradient change amount before the breakpoint is reached. The control device predicts the upcoming gradient change based on the current estimated load torque and pre-calculates the compensation value, which is then added to the target steering torque. This proactive approach prevents the pulse noise from occurring in the first place, rather than reacting after the noise is generated.
Solution Approach 2:
The patent changes the parameter of the target steering torque by adding a gradient change compensation amount. This modification adjusts the torque parameter dynamically based on the detected gradient change at map breakpoints, effectively smoothing the torque transition and eliminating the pulse noise while preserving the desired steering precision from the original map design.
2Stability of the object's composition
If proportional integral control is used to calculate base assist command, then gradient changes are suppressed, but calculation complexity increases
Solution Approach 1:
The patent applies partial action by implementing only the necessary proportional and integral control components rather than full PID control. The differential control component is deliberately omitted, as it is the source of the pulse noise problem. This partial implementation achieves the desired gradient suppression and noise elimination while keeping the calculation complexity manageable.
Data Source
AI summary
A servo controller calculates a base assist command, which is a basic command value of the assist torque, so that the steering torque follows a target steering torque. An estimated load torque calculation section calculates an estimated load torque. A target steering torque calculation section calculates a target steering torque using a map that defines a relationship between the estimated load torque and the target steering torque. The estimated load torque calculation section calculates the estimated load torque based on the steering torque or the target steering torque and an estimated load calculation assist command corresponding to a calculation result of only a proportional integral control calculation among the control calculations in the servo controller.