Adaptive Brake Disengagement Threshold for Directional Shifts
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Solution Overview
Problem
Existing braking systems in machines experience variable time delays during directional shifts, leading to premature or late disengagement of brakes, causing unsettling deceleration fluctuations or hesitation at zero speed due to fixed speed commands not accounting for deceleration rates and hydraulic fluid delays.
Innovation Solution
A controller determines a speed threshold based on the deceleration of the powertrain and a time delay associated with brake disengagement, commanding brake disengagement when the powertrain's output speed meets this threshold, ensuring smooth directional shifts without sudden deceleration losses or prolonged delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed speed threshold is used to command brake disengagement during directional shift, then the control logic is simple, but the brake disengagement occurs too soon or too late due to variable time delays, causing deceleration fluctuations or machine hesitation
Solution Approach 1:
The patent applies dynamics by transitioning from a static fixed speed threshold to a dynamic adaptive speed threshold that adjusts in real-time based on actual deceleration rate and estimated time delay. The controller continuously monitors deceleration and modifies the disengagement threshold accordingly, allowing the system to adapt to varying operating conditions and eliminate timing inaccuracies caused by fixed thresholds.
Solution Approach 2:
The patent implements parameter changes by modifying the speed threshold parameter from a constant value to a variable that changes based on deceleration rate and time delay characteristics. The disengagement speed threshold is calculated as a function of current speed, deceleration rate, and estimated hydraulic response time, enabling precise timing of brake disengagement despite variable system delays.
2Ease of manufacture
If brake command currents are transmitted at a preset fixed speed, then the control implementation is straightforward, but the hydraulic fluid movement delay causes the braking device to disengage at incorrect timing
Solution Approach 1:
The patent applies preliminary action by calculating and preparing the adaptive disengagement speed threshold in advance based on current deceleration rate and estimated time delay, before the actual brake disengagement command is issued. The controller proactively adjusts the threshold to compensate for the known hydraulic response delay, ensuring the brake disengages at the correct moment rather than reacting after the delay occurs.
Solution Approach 2:
The patent implements feedback by continuously monitoring the actual deceleration rate during directional shift and using this information to adjust the disengagement speed threshold in real-time. The controller creates a closed-loop system where the disengagement timing is based on actual measured deceleration rather than predetermined fixed values, automatically compensating for variations in hydraulic response time.
3Speed
If the brake disengagement timing is advanced to compensate for time delay, then the machine can move in the new direction without hesitation, but the deceleration rate decreases prematurely causing operator discomfort
Solution Approach 1:
The patent uses parameter changes to dynamically adjust the disengagement speed threshold based on the relationship between deceleration rate and time delay. By calculating the optimal threshold as a function of current operating parameters, the system determines the precise moment to disengage brakes that maintains smooth deceleration while ensuring timely transition to new direction, eliminating both premature and delayed disengagement issues.
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 approach allows for precise timing of brake disengagement, ensuring smooth deceleration and preventing machine hesitation during directional changes, enhancing operational stability and efficiency by accounting for variable deceleration rates and hydraulic delays.
Implementation Method 1
The brake valve responds to the brake command currents by changing the pressure within the braking device to tighten or loosen the braking device as commanded
Implementation Method 2
a time delay associated with movement of hydraulic fluid through the brake valve and associated hydraulic passages may occur after a command to disengage the braking device
Data Source
AI summary
A braking system is disclosed. The braking system may include a controller configured to determine a speed threshold that is based on a deceleration of an output speed of a powertrain of a machine caused in part by engagement of one or more brakes of the machine during a directional shift in a movement of the machine, the speed threshold being the output speed of the powertrain at which the one or more brakes are to be commanded to disengage. The controller may be configured to command disengagement of the one or more brakes based on a determination that the output speed of the powertrain satisfies the speed threshold.