Dump Truck Speed Control for Wheel Slip-Limited Travel
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Solution Overview
Problem
Conveying vehicles, such as dump trucks, face challenges with wheel slip during unattended operation, leading to reduced traveling efficiency and increased braking distances due to the need for gradual speed changes to prevent wheel slip.
Innovation Solution
The implementation of a vehicle control system that calculates and sets target travel speeds based on the maximum acceleration and deceleration limits, which are determined by the slip limit values calculated at various positions along the travel route, ensuring the wheels maintain a grip state and preventing slip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gradual speed changes are implemented to prevent wheel slip, then wheel slip is suppressed, but traveling efficiency decreases due to longer acceleration and braking distances
Solution Approach 1:
The patent dynamically adjusts the target travel speed based on real-time road surface conditions (slip limit values) at different positions along the travel route. The control device calculates optimal acceleration and deceleration rates that adapt to changing road conditions, allowing the vehicle to maintain grip state while maximizing travel efficiency. This resolves the contradiction by making the speed control dynamic rather than fixed, enabling efficient travel on good surfaces while preventing slip on slippery surfaces.
Solution Approach 2:
The system changes the operational parameters (target travel speed, acceleration rate, deceleration rate) based on the slip limit values detected at different positions. By continuously monitoring road surface conditions and adjusting speed parameters accordingly, the system achieves both slip prevention and efficient travel. The parameter changes allow the vehicle to optimize its motion profile for each specific road condition encountered.
2Reliability
If speed limit is changed based on travel path ranking, then wheel slip is reduced, but braking control is lost when vehicle stops at target position due to sudden deceleration
Solution Approach 1:
The control device calculates the target travel speed at each position before the vehicle reaches that position, taking into account the deceleration required to stop at the target position. By preliminarily planning the speed profile and ensuring smooth deceleration from a distance, the system prevents sudden braking that would cause slip. This preliminary action ensures both slip reduction and maintained braking control throughout the stopping process.
Solution Approach 2:
The system dynamically adjusts the deceleration rate based on real-time road surface conditions and the distance to the target position. Rather than applying fixed deceleration rates, the control device continuously optimizes the braking profile to match current grip conditions, preventing wheel slip during braking while maintaining effective stopping control. This dynamic approach resolves the contradiction between slip reduction and braking control.
3Reliability
If maximum acceleration and deceleration are calculated from slip limit values, then wheel grip is maintained, but device complexity increases due to continuous calculation and monitoring requirements
Solution Approach 1:
The control device uses the vehicle's existing sensors (wheel speed sensors, position sensors) and onboard computing resources to perform the slip limit value calculations and target speed determinations. Rather than adding dedicated hardware for each function, the system leverages existing components to self-monitor and self-adjust, reducing overall device complexity while maintaining reliable grip control through continuous calculation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables conveying vehicles to travel efficiently while minimizing the risk of wheel slip, thereby reducing braking distances and maintaining control during operation, thus enhancing both safety and efficiency.
Implementation Method 1
a wheel speed sensor 204 that detects rotation speed of the wheels 103
Implementation Method 2
an inertial sensor 203 that detects acceleration and angular speed of the vehicle body 101
Implementation Method 3
In the grip state, the wheel has a grip force against the road surface, and for example, braking of the vehicle is possible
Data Source
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AI summary
Provided is a conveying vehicle that ensures efficiently travelling while suppressing vehicle slip. A dump truck 100 includes a vehicle body 101 provided with wheels 103 and a vehicle control device 300 and travels on a travel route. The vehicle control device 300 calculates and stores slip limit values at a plurality of positions on the travel route, reads out the slip limit values to calculate at least one of a maximum acceleration and a maximum deceleration of the dump truck 100 at which the wheels 103 is capable of maintaining a grip state against a road surface, and sets a target travel speed at a travel position between the dump truck 100 and a target position according to a target speed at the target position and at least one of the maximum acceleration and the maximum deceleration.