ABS Torque Assist for Wheel Inertia Management
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Solution Overview
Problem
Large wheels on vehicles, such as tractors, experience inertia issues during braking, leading to incorrect ABS operation, especially on low-friction surfaces, causing wheels to potentially lock up and resulting in vehicle instability.
Innovation Solution
Applying torque to assist wheel acceleration during braking force release periods, using a prime mover and transmission system to maintain engine speed and adjust transmission ratios, ensuring the wheel's angular velocity aligns with vehicle speed, thus preventing incorrect ABS determinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the braking force is released during ABS operation, then the wheel should accelerate back towards vehicle speed, but the high inertia of large wheels prevents sufficient acceleration
Solution Approach 1:
The system applies a preliminary accelerating torque to the wheel during the brake release period to counteract the high inertia before the wheel can fall behind vehicle speed. This preventive action ensures the wheel accelerates sufficiently during the release phase without waiting for speed discrepancy to develop.
Solution Approach 2:
The system changes the torque parameter applied to the wheel during ABS operation. During brake release periods, an accelerating torque is applied to overcome inertia and ensure the wheel accelerates back towards vehicle speed, dynamically adjusting the torque based on wheel speed feedback.
2Measurement precision
If the wheel fails to accelerate during brake release periods, then the ABS monitoring becomes inaccurate, but increasing brake release duration allows more acceleration time
Solution Approach 1:
The system continuously monitors wheel speed during ABS operation and uses this feedback to determine when to apply accelerating torque. The feedback mechanism compares actual wheel speed with expected speed based on vehicle deceleration, triggering torque application when discrepancy exceeds a threshold, thereby maintaining accurate speed monitoring.
Solution Approach 2:
The system dynamically adjusts the brake release period duration and accelerating torque application based on real-time wheel speed feedback. The release period is extended or shortened, and torque is applied or withheld, depending on whether the wheel is accelerating sufficiently towards vehicle speed, optimizing both monitoring accuracy and acceleration performance.
3Reliability
If torque is applied to assist wheel acceleration, then the wheel angular velocity aligns with vehicle speed, but the system complexity increases
Solution Approach 1:
The existing prime mover and transmission system is made multi-functional by enabling it to provide both normal driving torque and ABS-assist accelerating torque. The same engine and transmission components serve dual purposes: propulsion during normal operation and wheel acceleration assistance during ABS brake release periods, avoiding additional dedicated hardware.
Solution Approach 2:
The system uses its own existing components (prime mover and transmission) to provide the accelerating torque needed during ABS operation. Rather than requiring an external or separate acceleration system, the vehicle's own powertrain serves the dual function of propulsion and wheel acceleration assistance, reducing overall system complexity.
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 minimizes the risk of ABS misjudging vehicle speed, ensuring effective braking and preventing wheel lockup, even on low-friction surfaces, by compensating for wheel inertia and maintaining accurate vehicle speed monitoring.
Implementation Method 1
such wheels will inherently have large inertia. In the case of vehicles such as dumpers, the rolling circumference of a wheel could be about 6 meters.
Implementation Method 2
The problem is aggravated where there is a low coefficient of friction between the ground and the wheel, e.g. where the ground is icy, such that the wheels may slip relative to the ground during periods in which the braking force is released.
Data Source
AI summary
A method of braking a vehicle which includes ground engaging wheels, and a braking system with ABS capability and including an operator actuated brake control, the ABS becoming operative in response to the operator actuating the brake control, and upon the braking system sensing the slippage or impending slippage of at least one of the ground wheels relative to the ground, to vary the braking force applied to the at least one of the wheels between, in alternative periods, an applied state in which the braking force is applied, and a released state in which the braking force is released, and characterised in that the method includes applying torque to assist acceleration of the wheel at least during periods in which the braking force is released by the ABS.