Dump Truck Brake Test Sequencing for Stable Loading
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Solution Overview
Problem
The emergency brake system in autonomous dump trucks can be stuck due to contamination, leading to excessive impact during loading operations when both front and rear brakes are actuated simultaneously, and potential overrunning when brakes are released simultaneously, causing instability during loading operations.
Innovation Solution
A dump truck equipped with a controller that determines when the vehicle is stopped and the vessel is in the fallen position, allowing for alternate testing of the front and rear emergency brake systems by measuring secondary pressures of the solenoid valves, ensuring proper actuation and preventing simultaneous brake release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the emergency brake system is tested frequently to prevent solenoid valve sticking, then reliability is improved, but excessive impact is imposed on the vehicle body during loading operations
Solution Approach 1:
The controller performs preliminary checks before executing emergency brake tests. It determines whether the vehicle is stopped, whether the vessel is in the fallen position, and whether loading operations are completed before allowing the brake test to proceed. This preliminary action prevents excessive impact during loading by ensuring safe timing conditions are met.
Solution Approach 2:
The controller continuously monitors vehicle state parameters (stopped status, vessel position, loading completion status) and uses this feedback to control when emergency brake tests can be executed. The feedback mechanism prevents testing during inappropriate conditions, thereby avoiding excessive impact on the vehicle body while still maintaining brake system reliability.
2Ease of operation
If both front and rear emergency brake systems are released simultaneously, then operational simplicity is improved, but the vehicle body may overrun due to impact and inertial force
Solution Approach 1:
The controller segments the brake release operation into sequential phases rather than simultaneous release. It releases the front wheel emergency brake system first, waits for a predetermined time period, then releases the rear wheel emergency brake system. This segmentation maintains operational simplicity while preventing vehicle body overrunning by staggering the release timing.
Solution Approach 2:
The controller implements periodic action by introducing a predetermined time delay between releasing the front and rear brake systems. This periodic release pattern allows the vehicle to adjust gradually to the braking changes, maintaining stability while keeping the operation simple and automated.
3Reliability
If the solenoid valve is kept closed to prevent contamination, then reliability is improved, but the spool may get stuck due to lack of movement
Solution Approach 1:
The controller implements periodic opening and closing of the solenoid valve during emergency brake tests. This periodic action ensures the spool moves regularly to prevent sticking from contamination, while maintaining high reliability by controlling the timing and conditions of these movements through automated testing sequences.
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
Enables appropriate timing for emergency brake system actuation tests, preventing excessive impact and overrunning by ensuring the brakes are tested and functioning correctly, thus maintaining vehicle stability during loading operations.
Implementation Method 1
a hydraulic pump that transfers hydraulic oil
Implementation Method 2
a front wheel accumulator and a rear wheel accumulator that are configured to accumulate the hydraulic oil supplied from the hydraulic pump
Implementation Method 3
a front wheel solenoid valve and a rear wheel solenoid valve that are configured to open and close a flow path of the hydraulic oil
Implementation Method 4
a front wheel brake device and a rear wheel brake device that are configured to be actuated by the hydraulic oil
Data Source
AI summary
Provided is a dump truck capable of performing an actuation test of an emergency brake system at an appropriate timing. The dump truck comprises: front wheel and rear wheel emergency brake systems, each system including an accumulator that accumulates hydraulic oil supplied from a hydraulic pump, a brake device that is actuated by the hydraulic oil supplied from the accumulator, and a solenoid valve that opens and closes a flow path of the hydraulic oil extending from the accumulator to the brake device; and a controller configured to execute front test processing and rear test processing alternately (step S16/step S18) in the case of determining that the dump truck is stopped (step S11: Yes), a vessel is in a fallen position (step S12: YES), and a loading operation onto the vessel is completed (step S15: Yes/step S17: Yes).