Blended ABS and Stability Control Brake Command Adjustment
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Solution Overview
Problem
Existing brake systems that combine anti-lock braking system (ABS) and dynamic stability control (DSC) often face conflicts between their commands, particularly when handling situations that require simultaneous adjustments, leading to potential wheel locking or instability during cornering.
Innovation Solution
A brake system that includes an anti-lock braking subsystem, a stability control subsystem, and a brake command adjustment subsystem to calculate and adjust brake commands for individual wheels, ensuring that both the maximum allowable brake command and desired differential brake command are met, either by finding an ideal solution or a non-ideal solution with the lowest cost, thereby optimizing braking control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ABS sets upper limits on braking force to prevent wheel locking, then wheel locking is prevented, but DSC optimal braking force may be restricted
Solution Approach 1:
The patent introduces a brake command adjustment subsystem as an intermediary between ABS and DSC control systems. This subsystem receives brake commands from both systems, validates them against ABS constraints, and adjusts DSC commands to satisfy both ABS safety limits and DSC stability requirements. The intermediary resolves the conflict by coordinating both control objectives rather than allowing them to operate independently with conflicting demands.
Solution Approach 2:
The system dynamically adjusts braking commands based on real-time validation of ideal versus non-ideal solutions. When DSC optimal commands conflict with ABS limits, the system transitions from ideal solution mode to non-ideal solution mode, dynamically adapting the braking strategy to satisfy both constraints. This dynamic adjustment allows the system to optimize for DSC when possible while falling back to safe ABS-compliant operation when necessary.
2Stability of the object's composition
If DSC applies asymmetric braking forces to correct yaw-rate, then cornering stability is improved, but wheel slip control may be compromised
Solution Approach 1:
The brake command adjustment subsystem acts as an intermediary that validates DSC asymmetric braking commands against ABS wheel slip constraints. It receives the differential brake command from DSC, calculates ideal left and right brake commands, and verifies they satisfy ABS maximum allowable brake commands. When conflicts arise, the system adjusts the commands to maintain both cornering stability and wheel slip control.
Solution Approach 2:
The system applies different braking strategies to left and right wheels based on local conditions. The brake command adjustment subsystem calculates separate ideal brake commands for left and right sides, allowing asymmetric DSC corrections to be applied locally to each wheel while individually validating against ABS constraints. This local quality approach enables targeted stability correction without compromising overall wheel slip control.
3Manufacturing precision
If the system calculates ideal solutions for brake commands to satisfy both ABS and DSC, then braking control precision is improved, but computational complexity increases
Solution Approach 1:
The patent segments the brake command calculation into distinct components: ABS maximum allowable brake command calculation, DSC desired differential brake command calculation, and brake command adjustment subsystem that combines them. The adjustment subsystem separately calculates ideal left and right brake commands, validates them independently against constraints, and determines validity separately for each side. This segmentation makes the complex calculation more manageable and systematic.
Solution Approach 2:
The system first attempts to calculate ideal solutions that fully satisfy both ABS and DSC requirements. Only when these ideal solutions are found to be invalid does the system proceed to calculate non-ideal solutions with the lowest cost. This partial action approach (trying ideal first, then non-ideal) optimizes computational effort by avoiding unnecessary complex calculations when simpler ideal solutions exist.
Data Source
AI summary
A brake system for a mobile machine is disclosed. The brake system may have an anti-lock braking subsystem configured to calculate a maximum allowable brake command. The brake system may have a stability control subsystem configured to generate a desired differential brake command. The brake system may have a brake command adjustment subsystem. The brake command adjustment subsystem may be configured to calculate an ideal solution of a left brake command and a right brake command to satisfy a combination of the desired differential brake command and a desired total brake command. When the ideal solution is valid, the brake command adjustment subsystem may output the ideal solution as an actual brake command. When the ideal solution is invalid, the brake command adjustment subsystem may calculate a non-ideal solution of the left brake command and the right brake command.