Modular Front Steering Assembly for Zero-Turn Radius Vehicles
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Solution Overview
Problem
Zero turn radius (ZT) vehicles face challenges with complex steering mechanisms, particularly during side-hill traverses, where downhill drift occurs, requiring disproportionate power outputs and compromising zero-radius turn capability, due to the mechanical coordination of front wheel steering with independent transmissions.
Innovation Solution
A modular front steering assembly with an electronic steering apparatus that integrates with the vehicle's subframe, providing both front wheel steering and control inputs, allowing for true zero-radius turn capability and simplifying the steering mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If mechanical linkages are used to coordinate front wheel steering with independent transmissions, then steering control is achieved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical linkages with an electronic control system. The electronic steering apparatus receives input from the operator and sends electronic signals to independently control the left and right transmissions, eliminating the need for mechanical coordination mechanisms while achieving precise steering control.
Solution Approach 2:
The steering system is divided into independent electronic control channels for the left and right transmissions. Each transmission is controlled separately through electronic signals, allowing independent adjustment of power delivery to each wheel, which simplifies the overall system architecture compared to interconnected mechanical linkages.
2Reliability
If front wheel steering is added to improve side-hill performance, then steering capability is improved, but zero-radius turn capability is compromised
Solution Approach 1:
The electronic control system dynamically adjusts the power delivery to left and right transmissions based on real-time steering input. During zero-radius turns, the system can independently control each transmission to maintain equal and opposite power delivery, preserving tight turning capability. During side-hill operation, the system dynamically compensates for gravitational effects while maintaining steering responsiveness.
Solution Approach 2:
The system changes operational parameters of the transmissions independently through electronic control. By adjusting speed, torque, and power delivery parameters separately for each transmission, the system can optimize performance for different operating conditions including both zero-radius turns and side-hill traverses without mechanical compromise.
3Stability of the object's composition
If disproportionate power outputs are applied to maintain straight line tracking on downhill, then tracking stability is improved, but energy efficiency deteriorates
Solution Approach 1:
The electronic steering apparatus incorporates feedback mechanisms that monitor vehicle position, steering input, and transmission performance. This feedback allows the control system to make real-time adjustments to power delivery, applying minimal necessary correction to maintain straight-line tracking on downhill terrain rather than requiring continuous disproportionate power output.
Solution Approach 2:
The electronic control system automatically compensates for downhill gravitational effects through intelligent power distribution to the transmissions. The system self-adjusts based on detected conditions, providing stable tracking without requiring excessive operator input or wasteful power application, as the electronic controls continuously optimize the power balance.
Data Source
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AI summary
The invention provides for a modular front steering assembly adapted to integrate with a vehicle having a prime mover (18), a subframe (22), an accelerator, a brake, a power source (28), and a pair of variable drive units (12L, 12R) actuated by a mechanical combination, each variable drive unit driving one of a pair of axles, the modular front steering assembly comprising: a frame member, non-integral with the subframe, having opposed ends and adapted for attachment to the subframe; a first wheel assembly attached to a first end of the frame member and pivotable about a first vertical steering axis and a second wheel assembly attached to a second end of the frame member and pivotable about a second vertical steering axis; a steering mechanism operatively connected to the first and second wheel assemblies (24), the steering mechanism comprising a steering column (46) directly connected to the frame member and a steering input device; an electronic drive control system (30) adapted to independently adjust the speed and rotational direction of the output from each variable drive unit, comprising: a pair of electric actuators (52L, 52R), each adapted for attachment to one of the variable drive units and to adjust the position of the mechanical combination; a steering position sensor (48); an accelerator position sensor (72); a first speed sensor (56L) adapted for sensing the speed of one of the axles and a second speed sensor (56R) adapted for sensing the speed of the other of the axles; and a controller (50) in communication with the accelerator position sensor, the steering position sensor, the first speed sensor, the second speed sensor, and the pair of electric actuators, and the controller adapted to be in communication with the prime mover and the power source.