Steering Apparatus Dynamic Current Limiting for Obstacle Detection
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Solution Overview
Problem
Steering apparatuses face challenges in properly detecting contact between turning wheels and obstacles, particularly due to overheating issues when the current supplied to the turning motor exceeds thresholds, leading to false detection and reduced turning performance.
Innovation Solution
A steering apparatus with a control device that includes multiple computation circuits to dynamically adjust the current limiting values and thresholds, ensuring proper detection of wheel contact by limiting the current to the smallest absolute value and adjusting thresholds accordingly, while minimizing overheating and maintaining turning performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the current threshold is set to detect wheel-obstacle contact, then obstacle detection capability is improved, but the turning motor may overheat when the current is limited by temperature control
Solution Approach 1:
The patent applies dynamics by making the current threshold dynamic rather than fixed. The threshold computation circuit adjusts the threshold value based on the limiting value computed from motor temperature. When temperature is high and current is limited, the threshold is automatically reduced to match the limited current level, ensuring detection remains effective under varying thermal conditions.
Solution Approach 2:
The patent changes the parameter of current threshold based on temperature conditions. The threshold computation circuit modifies the threshold value according to the relationship between limiting value and actual current, adapting the detection parameter to the current operational state of the motor to maintain detection accuracy while preventing false alarms.
2Temperature
If the current amount to turning motor is limited to prevent overheating, then motor temperature control is improved, but obstacle contact detection may fail when current does not reach threshold
Solution Approach 1:
The patent implements feedback by having the threshold computation circuit continuously monitor the relationship between limiting value and actual current, and adjust the threshold accordingly. When current limitation is active due to temperature concerns, the feedback mechanism ensures the threshold is reduced to match the limited current level, maintaining reliable obstacle detection despite the reduced current available for turning.
3Measurement precision
If multiple computation circuits are added to dynamically adjust current limits and thresholds, then detection accuracy and temperature control are improved, but device complexity increases
Solution Approach 1:
The patent merges the threshold computation function with the existing control device architecture. The threshold computation circuit is integrated into the control system and works in conjunction with the limiting value computation circuit, combining multiple functions into a coordinated system rather than adding completely separate independent systems, thereby managing complexity while achieving accurate detection and temperature control.
Data Source
AI summary
A steering apparatus includes: a mechanism that turns a turning wheel; a first motor that generates a driving force that is given to the mechanism; and a control device. The control device includes: a first computation circuit that computes a first limiting value to which an electric current to be supplied to the first motor is limited in a particular situation; a determination circuit that determines whether the turning wheel is in touch with an obstacle; a second computation circuit that computes a second limiting value to which the electric current to be supplied to the first motor is limited when the determination circuit determines that the turning wheel is in touch with the obstacle; and a third computation circuit that computes the threshold to be used by the determination circuit, based on a smaller limiting value of the first limiting value and the second limiting value.