Rear Wheel Steering Control via Sequential Motor Activation
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Solution Overview
Problem
Existing vehicle steering systems lack efficient control mechanisms for distributing steering tasks between front and rear wheels, leading to suboptimal steering performance and increased mechanical complexity.
Innovation Solution
A method and apparatus that utilize position sensors and controllers to sequentially control front and rear steering motors or gears, allocating specific ranges of steering wheel rotation to either the front or rear wheels, thereby optimizing steering performance and reducing mechanical load on the steering system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If both front and rear steering motors are active simultaneously, then steering performance is improved, but mechanical complexity and hydraulic pump size increase
Solution Approach 1:
The steering control is segmented into distinct operational modes: front wheel steering mode, rear wheel steering mode, and combined steering mode. The controller selectively activates only the necessary steering motors based on driving conditions, dividing the steering function into manageable segments that reduce simultaneous mechanical load and complexity
Solution Approach 2:
The system periodically switches between different steering configurations based on vehicle speed and steering angle thresholds. At different operational phases (periods), different steering motors are activated - front wheels dominate at low speeds, rear wheels at high speeds, creating a rhythmic activation pattern that reduces peak mechanical demands
2Measurement precision
If both front and rear steering motors are active simultaneously, then steering precision is improved, but hydraulic pump size and cost increase
Solution Approach 1:
The system applies partial steering action by activating only one steering motor at a time based on operational needs. Instead of always engaging both front and rear steering motors fully, the system uses partial activation of appropriate motors, which maintains steering precision while reducing hydraulic flow requirements and pump size
3Device complexity
If front steering gear is used for all steering operations, then system simplicity is maintained, but steering performance at high speeds deteriorates
Solution Approach 1:
The steering system transitions from a static configuration to a dynamic one where the active steering components change based on vehicle speed and steering angle. The controller dynamically switches between front wheel steering, rear wheel steering, and combined steering modes, allowing the system to adapt its complexity to match performance requirements at different operating conditions
Data Source
AI summary
An apparatus (10) for use in turning steerable wheels of a vehicle (12) upon manual rotation of a steering wheel (14) comprises a front steering motor (36) coupled to a front steerable wheel (18) of the vehicle (12) for turning the front steerable wheel. A rear steering motor (66) is coupled to a rear steerable wheel (22) of the vehicle (12) for turning the rear steerable wheel. A position sensor (34) senses a rotational position of the steering wheel (14) and provides an output indicative of said rotational position. A controller (90) receives the output of the position sensor (34) and controls the front and rear steering motors (36, 66) to turn the front steerable wheel (22) in response to the output from the position sensor (34) indicating rotation of the steering wheel (14) in a first portion of a range of rotation of the steering wheel. The controller (90) also controls the front and rear steering motors (36, 66) to turn only the rear steerable wheel (22) in response to the output from the position sensor (34) indicating rotation of the steering wheel (14) in a second portion of the range of rotation of the steering wheel.