Utility Vehicle Speed Control Under Rough-Terrain Vibration
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Solution Overview
Problem
Utility vehicles experience unintended changes in travel speed due to body shakes caused by traveling on rough terrain, leading to erroneous operations of the accelerator pedal.
Innovation Solution
A utility vehicle configuration that includes a drive controller generating a driving signal based on the amount of accelerator pedal operation and detected vertical acceleration, using a low pass filter to attenuate signal changes and adjust the time constant according to acceleration levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the accelerator pedal operation is directly translated to driving signal without considering body acceleration, then the response to driver input is immediate, but the travel speed changes unintentionally due to body shakes on rough terrain
Solution Approach 1:
The drive controller detects vertical acceleration of the body and feeds this information back to adjust the driving signal. When acceleration exceeds a threshold, the controller attenuates the change amount of the driving signal, preventing unintended speed changes caused by body shakes while maintaining accurate speed control.
Solution Approach 2:
The system dynamically changes the parameter of driving signal change amount based on detected acceleration levels. When acceleration is high, the change amount is reduced; when acceleration is low, normal response is maintained. This adaptive parameter adjustment resolves the contradiction between immediate response and preventing unintended changes.
2Reliability
If the drive controller reduces the change amount of driving signal when acceleration is high, then unintended speed changes are prevented, but the response to legitimate driver input may be delayed
Solution Approach 1:
The drive controller dynamically adjusts the attenuation level based on real-time acceleration detection. The system is not statically reduced but adaptively modulates the driving signal change amount according to current vibration conditions, maintaining reliability while minimizing unnecessary delays in legitimate driver input response.
Solution Approach 2:
The system applies partial attenuation only when necessary (when acceleration exceeds threshold), rather than continuously reducing response. This partial action approach maintains full responsiveness during normal conditions while providing just enough attenuation during vibrations to prevent unintended speed changes.
3Ease of operation
If no acceleration detection is performed, then the control system remains simple, but the accelerator pedal operations become erroneous due to body shakes
Solution Approach 1:
The system replaces complex mechanical vibration damping mechanisms with an electronic detection and control system. An acceleration detector electronically senses body shakes, and the drive controller electronically adjusts the driving signal, substituting mechanical complexity with electronic control that is easier to implement and adjust.
Data Source
AI summary
The utility vehicle includes a body; a travel device provided for the body; a driving source configured to drive the travel device; an acceleration operating member configured to receive an operation for adjusting a travel speed of the utility vehicle; a drive controller configured to generate a driving signal for the driving source; and an acceleration detector configured to detect a vertical acceleration of the body relative to ground, and the drive controller is configured to generate the driving signal based on (i) an amount of the operation that the acceleration operating member receives and (ii) the acceleration.