Steering Motor Acceleration Control for Materials Handling Vehicles
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Solution Overview
Problem
Existing materials handling vehicles with steer-by-wire systems lack effective control over traction motor acceleration, particularly in determining optimal acceleration values based on angular position, speed, and operational modes, leading to inefficient steering and motor control.
Innovation Solution
A control apparatus that determines acceleration reduction factors based on the angular position of a steerable wheel, traction motor speed, and operator-defined speed control signals, selecting the factor causing the greatest reduction in acceleration to generate an updated drive signal for the traction motor, thereby optimizing motor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the traction motor acceleration is increased to improve vehicle responsiveness, then the vehicle can accelerate faster and be more responsive to operator input, but the steering stability deteriorates especially during turns when the steerable wheel is at extreme angles
Solution Approach 1:
The patent implements dynamic adjustment of acceleration values based on real-time steering conditions. The control apparatus continuously monitors the angular position of the steerable wheel and automatically selects appropriate acceleration values from multiple stored options. When the wheel is at extreme angles, the system dynamically reduces acceleration to maintain stability, while allowing higher acceleration when the wheel is in neutral positions, thus resolving the contradiction between responsiveness and steering stability.
2Adaptability or versatility
If a fixed acceleration value is used for the traction motor, then the control system is simple and reliable, but the vehicle cannot adapt to different steering conditions and operational modes resulting in suboptimal performance
Solution Approach 1:
The patent applies parameter changes by storing multiple acceleration values in the control apparatus and selecting the appropriate value based on current operating conditions. The system changes the acceleration parameter dynamically according to the angular position of the steerable wheel and operational mode, enabling adaptation to different steering conditions without requiring a completely complex control architecture. This resolves the contradiction by implementing adaptable control through manageable parameter variation.
3Stability of the object's composition
If acceleration reduction is applied during steering to maintain stability, then steering stability is improved, but the vehicle loses speed and responsiveness
Solution Approach 1:
The patent applies local quality by implementing acceleration reduction only in specific local conditions - namely when the steerable wheel is at extreme angular positions. When the wheel is in neutral or moderate positions, the system maintains full acceleration values to preserve vehicle speed and responsiveness. This localized application of acceleration control resolves the contradiction by applying stability measures only where needed rather than globally, thus maintaining overall vehicle performance.
Data Source
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AI summary
A materials handling vehicle (10) is provided comprising: a frame (20) comprising an operator's compartement; wheels (58, 74) supported on said frame; a traction motor (72) coupled to one of said wheels, being a steerbale wheel (74), to effect rotation of said steerable wheel; a system (80) associated with said steerable wheel to effect angular movement of the steerable wheel about a first axis (A1); said system comprising a control handle capable of being moved by an operator to define a desired angular position of said steerable wheel; control apparatus (200, 96) varying a drive signal to said traction motor based on a steerable wheel error.