Brake Pressure Modulation for End-of-Stop Jerk Reduction
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Solution Overview
Problem
Existing vehicles experience unpleasant end of stop (EOS) jerk due to inconsistent brake feedback and rock-back motion, primarily caused by the transition from dynamic to static friction, which is not effectively addressed by prior methods that rely on instantaneous speed measurements, leading to inaccurate braking and increased stopping distance.
Innovation Solution
A brake system and controller that estimate the time until the vehicle stops and adjust the brake pressure accordingly, reducing the applied pressure just before stopping to mitigate EOS jerk, while also considering the grade of the driving surface to modulate the brake pressure reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If brake pressure is applied to stop the vehicle, then the vehicle comes to a stop, but end of stop jerk occurs due to transition from dynamic to static friction
Solution Approach 1:
The system performs preliminary action by reducing brake pressure before the vehicle comes to a complete stop. The controller estimates the time until the vehicle stops and proactively modulates the brake pressure to prevent the transition from dynamic to static friction that causes jerk, rather than reacting after the jerk occurs.
Solution Approach 2:
The system applies dynamics by continuously adjusting brake pressure based on real-time conditions. The controller modulates brake pressure dynamically during the stopping process, transitioning from constant pressure to variable pressure control as the vehicle approaches stop, allowing smooth adaptation to changing friction conditions.
2Object-affected harmful factors
If prior methods reduce brake pressure to minimize jerk, then jerk is reduced, but stopping distance increases due to inaccurate braking
Solution Approach 1:
The system implements feedback by continuously monitoring vehicle speed, deceleration rate, and estimated time to stop. The controller uses this feedback information to adjust brake pressure in real-time, ensuring that pressure reduction occurs at the optimal moment to reduce jerk while maintaining efficient stopping distance through precise control.
Solution Approach 2:
The system replaces mechanical speed measurement methods with an electronic estimation approach. The controller estimates time until stop using electronic sensors and computational algorithms, providing more accurate and timely information for brake pressure modulation compared to traditional mechanical speed measurements, thereby preventing both excessive jerk and extended stopping distance.
3Productivity
If instantaneous speed measurements are used for braking control, then braking response is achieved, but measurement inaccuracy leads to increased stopping distance
Solution Approach 1:
The system substitutes mechanical speed measurement with an electronic estimation method. The controller estimates time until stop by integrating deceleration data from sensors, providing more precise and responsive measurement than mechanical speed sensors, thereby improving both braking response and stopping distance accuracy.
Solution Approach 2:
The system introduces an intermediary estimation process between the physical vehicle motion and the brake control system. Rather than directly using instantaneous speed measurements, the controller estimates time until stop as an intermediate parameter that more accurately reflects the vehicle's stopping trajectory, enabling better-brake pressure timing and reducing measurement errors.
Data Source
AI summary
Methods, apparatus, systems, and articles of manufacture to reduce end of stop jerk are disclosed. An example vehicle includes a user interface, a brake system, and a controller to execute instructions to detect a command to engage the brake system at a command brake pressure, estimate a time until the vehicle comes to a stop, and in response to determining that the time satisfies a time threshold, engage the brake system at a delivered brake pressure less than the command brake pressure.