Steering Ratio Controller Damping Gain Locking Mechanism Load
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Solution Overview
Problem
Conventional steering transmission ratio variable devices face issues with excessive load on the locking mechanism due to sudden increases in steering torque, leading to potential damage and increased costs, as the motor speed increases when switching to a locked state without adequate consideration for changing steering loads.
Innovation Solution
A controller for the steering transmission ratio variable device that adjusts the motor drive voltage by setting a damping gain higher than the unlocked state to reduce motor speed and apply a steady state gain corresponding to the steering load, thereby controlling the motor to maintain balance and restrict increases in speed during the locking process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the locking mechanism is engaged to restrict relative rotation between steering input shaft and steering output shaft, then the steering transmission ratio is fixed and mechanical stability is improved, but the load on the locking mechanism becomes excessively large due to sudden motor speed increase
Solution Approach 1:
The controller executes preliminary actions by gradually increasing the drive voltage from a first value to a second value before the locking mechanism is fully engaged. This gradual voltage increase prevents sudden motor speed changes that would otherwise create excessive load on the locking mechanism during engagement
Solution Approach 2:
The control system dynamically adjusts the drive voltage based on the engagement state of the locking mechanism. The controller monitors whether the locking mechanism is engaged or disengaged and modifies the motor control strategy accordingly, transitioning from a first control strategy during engagement to a second control strategy after engagement
2Adaptability or versatility
If the motor rotates relative to the steering input shaft during steering operation, then the steering transmission ratio can be varied, but the motor speed increases excessively when steering torque changes suddenly near the turning angle end position
Solution Approach 1:
The controller continuously monitors the drive voltage, steering torque, and engagement state of the locking mechanism. Based on this feedback, the controller dynamically adjusts the drive voltage to maintain appropriate motor speed, particularly when steering torque changes suddenly near the turning angle end position
Solution Approach 2:
The controller changes the drive voltage parameter from a first value to a second value based on the engagement state of the locking mechanism and the current steering operating conditions. This parameter change prevents excessive motor speed increase while maintaining the ability to vary steering transmission ratio
3Stability of the object's composition
If the motor supplies only holding torque when switching to locked state, then the motor maintains position, but the balance between steering load and holding torque is disrupted when steering load changes excessively, causing motor speed increase
Solution Approach 1:
The controller dynamically adjusts the drive voltage from a first value to a second value based on whether the locking mechanism is engaged or disengaged. This dynamic adjustment ensures the motor can handle excessive steering load changes while maintaining position stability during the transition to locked state
Solution Approach 2:
The control parameter (drive voltage) is changed based on the engagement state of the locking mechanism. When the locking mechanism is disengaged, the controller uses a first drive voltage value to maintain position stability. When engaged, the controller transitions to a second drive voltage value to prevent motor speed increase due to steering load changes
Data Source
AI summary
A device for controlling a steering transmission ratio variable device, which is provided with: a motor, which is able to apply a driving force that promotes relative rotation between a steering output shaft coupled to wheels to be turned and a steering input shaft that applies a steering input to the steering output shaft to one of either the steering output shaft or the steering input shaft; a motor driving device that drives the motor; and a locking device that is able to restrict the relative rotation, has a setting device that prescribes a drive voltage the motor and sets a damping gain, which acts in a direction that reduces a rotating speed of the motor, to a value that is larger than a reference value corresponding to an unlocked state during a locking control period in which a state of the steering transmission ratio variable device switches from an unlocked state in which the relative rotation is not restricted to a locked state in which the relative rotation is restricted.