Vehicle Lift Gate Obstacle Detection via Direct Optical Sensing
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Solution Overview
Problem
Existing obstacle detection systems in automated vehicle parts, such as lift gates, face challenges in sensitivity and response time due to mechanical backlash and indirect sensing techniques, which can lead to damage or injury when detecting obstacles at the end of travel.
Innovation Solution
A direct sensing technique that uses an angle sensor to provide absolute position feedback to a controller, allowing for digital pulsewidth modulation-based drive signal adjustments to enhance obstacle detection sensitivity and response speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If indirect sensing techniques (Hall Effect sensors or optical vane interrupt sensors) are used in the motor or drive mechanism, then velocity control and obstacle detection can be implemented, but mechanical backlash and system flex cause delayed obstacle detection at the end of travel
Solution Approach 1:
The patent replaces indirect mechanical sensing (Hall Effect sensors, optical vane interrupt sensors) with direct optical sensing using an opto-interrupter positioned on the vehicle body that detects the lift gate's position directly without mechanical transmission components. This eliminates backlash and flex issues inherent in mechanical drive trains.
Solution Approach 2:
The patent introduces an opto-interrupter as an intermediary sensing element that optically detects the lift gate's position and velocity. This opto-interrupter acts as a mediator between the mechanical system and the controller, providing accurate position feedback without being subject to mechanical backlash.
2Reliability
If the drive mechanism transitions from negative energy state to positive energy state to detect obstacles, then obstacle detection can occur, but the process takes hundreds of milliseconds which is too long to prevent injury or damage
Solution Approach 1:
The patent implements preliminary obstacle detection by continuously monitoring the lift gate's position and velocity using the opto-interrupter before the drive mechanism needs to transition energy states. This allows the controller to detect obstacles and initiate reverse operation immediately upon detection, rather than waiting for energy state transitions.
Solution Approach 2:
The patent establishes a continuous feedback loop where the opto-interrupter provides real-time position and velocity information to the controller, which then adjusts the drive mechanism accordingly. This feedback mechanism enables rapid obstacle detection and response without relying on energy state transitions.
3Speed
If Hall Effect sensors or optical vane interrupt sensors are positioned in the motor or mechanical drive train, then velocity sensing is possible, but mechanical backlash reduces detection accuracy at the end of travel
Solution Approach 1:
The patent replaces mechanical velocity sensing methods with direct optical position sensing. The opto-interrupter measures position directly on the lift gate, and velocity is derived from position changes over time, eliminating the need for mechanical sensors in the drive train that are subject to backlash.
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
The direct sensing technique improves obstacle detection sensitivity and reduces system wear by knowing the rotational closure system's position before, during, and after movement, enabling faster response to obstacles and preventing damage.
Implementation Method 1
A new technique uses an opto-interrupter, positioned on the vehicle body, to sense position and velocity of the lift gate
Data Source
AI summary
A system and method for controlling a rotational closure system, such as a lift gate, of a vehicle may include sensing an angle of the rotational closure system, generating a drive signal, driving a drive mechanism with the drive signal to output a mechanical force for moving the rotational closure system, generating an angle signal having a digital pulsewidth modulation form with a duty cycle based on the angle of the rotational closure system, feeding back the angle signal, and, in response to the feedback angle signal, altering the drive signal while the drive mechanism is moving the rotational closure system between open and closed positions. In one embodiment, the angle signal is generated from a location disposed on the rotational closure system. A controller mounted to the rotational closure system may include an angle sensor and be configured to receive and process the angle signal to drive the drive mechanism.