Drive-By-Wire Steering With Zero Caster Trail for Slope Stability
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Solution Overview
Problem
Existing outdoor power equipment with dummy caster wheels face difficulties in maintaining alignment and steering, especially on slopes, due to gravity-induced orientation changes, leading to undesirable behavior and reduced maneuverability.
Innovation Solution
The implementation of a drive-by-wire system with actively steered wheels having zero or substantially zero caster trail, combined with variable output damping, drive system loss compensation, and a floating neutral point, to improve steering and hill handling by emulating hydrostatic drive systems and adjusting control inputs for enhanced control and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If dummy caster wheels are used to support non-driven ends of outdoor power equipment, then the equipment can rotate orientation to appropriate angles during turning, but gravity causes the caster wheels to rotate away from proper alignment when driving straight along a hill, making steering extremely difficult
Solution Approach 1:
The patent replaces the passive mechanical caster wheel system with an active drive-by-wire steering system using steerable wheels having zero or substantially zero caster trail. These wheels are controlled by a control system that actively maintains proper alignment regardless of slope conditions, eliminating the gravity-induced alignment problems of traditional caster wheels.
Solution Approach 2:
The patent changes the caster trail parameter from a non-zero value (traditional caster wheels) to zero or substantially zero (steerable wheels). This parameter change fundamentally alters the wheel behavior, allowing the wheels to maintain proper alignment without being influenced by gravity on slopes, while still enabling effective steering through active control.
2Measurement precision
If traditional caster wheel systems are used, then the equipment structure is simple, but steering precision and alignment maintenance on slopes are poor
Solution Approach 1:
The patent replaces the simple passive caster wheel mechanism with a controlled steerable wheel system featuring zero caster trail. This substitution increases steering precision by eliminating gravity-induced alignment drift on slopes, while the added complexity is managed through electronic control systems that actively maintain wheel orientation.
Solution Approach 2:
The patent modifies the caster trail parameter to zero or substantially zero, which fundamentally improves steering precision on slopes. This parameter change requires配套的 control systems to actively manage wheel orientation, transforming the system from passive to active control architecture.
Data Source
AI summary
Systems and methods for drive and steering control in a drive-by-wire system for outdoor power equipment are discussed. Various embodiments can employ techniques related to one or more of: steering based on actively steered wheels with zero caster trail, variable output damping of vehicle control outputs, steering that compensates for drive system loss, emulation of drivability of a hydrostatic drive system by a non-hydrostatic drive system, employing a floating neutral point to improve steering on slopes, open loop techniques for hill holding and speed compensation on hills, and/or adjustment of a speed range associated with control inputs.