Rear-Wheel Steering Control for Battery Power Saving
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Solution Overview
Problem
Conventional rear-wheel steering systems face challenges in reducing battery exhaustion while maintaining steering effectiveness, particularly at high rudder angles, leading to inefficient electric power consumption and reduced steering range.
Innovation Solution
A control apparatus that includes a steering force supplying device and an electrification controlling device, which adjusts the electric power supply based on the deviation between the target and actual rudder angles, cutting power when the actual angle exceeds a reference value to prevent waste and optimize battery usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the drive current is reduced simply near the rudder angle end as disclosed in patent document 2, then the battery exhaustion can be suppressed, but the range in which the rudder angle control can be performed is reduced from the start, and the effects of the rear-wheel steering apparatus are significantly reduced
Solution Approach 1:
The patent applies dynamics by making the drive current reduction strategy adaptive rather than static. The control apparatus dynamically adjusts the drive current based on real-time detection of the rudder angle and deviation from the target angle, allowing the system to maintain full control range when needed while reducing power consumption when the target is approached.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the actual rudder angle against the target rudder angle and using this deviation information to modulate the drive current. This feedback mechanism ensures that the system maintains precision near the target angle while avoiding unnecessary power consumption, resolving the contradiction between energy savings and control range.
2Force
If the physical load is high in the rudder angle range near the end, then the steering force can be sufficiently supplied to promote steering of the rear wheels, but the exhaustion of storage battery devices increases
Solution Approach 1:
The patent applies parameter changes by modulating the drive current parameter based on the operating conditions. When the rudder angle approaches the target angle with high physical load, the system reduces the drive current parameter to prevent excessive battery exhaustion, while still maintaining sufficient steering force through the controlled reduction rather than complete shutdown.
Solution Approach 2:
The patent implements partial action by applying drive current reduction only partially and selectively in the high-load rudder angle range near the end, rather than reducing it completely or uniformly across all operating conditions. This partial reduction maintains sufficient steering force while preventing excessive battery exhaustion.
Data Source
AI summary
In a vehicle provided with an ARS actuator and an ARS driving apparatus as the rear-wheel steering apparatus, an ECU performs ARS electric power saving control. In the control, electric power supply to the ARS actuator is cut under the conditions that a rudder angle deviation Δδr is greater than a reference deviation Δδth and that a duration Tlst exceeds a reference value Tlstth in cases where a rear-wheel rudder angle δr is greater than a reference rudder angle δrth, wherein the rudder angle deviation Δδr is a difference value between a target rear-wheel rudder angle δrtg and the rear-wheel rudder angle δr and the duration Tlst is a time in which the state that the rudder angle deviation Δδr is greater than the reference deviation Δδrth continues.