Area Monitoring Sensor With Hysteresis Threshold Occupancy Detection
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Solution Overview
Problem
Existing sensors, such as lidar systems, experience rapid fluctuations between 'occupied' and 'free' states when detecting objects due to varying distances and lateral positions, leading to unreliable monitoring, especially in autonomous vehicles.
Innovation Solution
A sensor with an evaluation unit that uses two distinct thresholds, an entry and exit threshold, to determine the occupied or free state of a monitored area, incorporating hysteresis to prevent rapid state changes by comparing estimated object dimensions or beam counts with these thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single threshold is used to determine object presence, then the detection sensitivity is high, but the monitoring state flickers rapidly between occupied and free states
Solution Approach 1:
The patent changes the threshold parameter from a single value to two distinct values (entry threshold and exit threshold). When an object is detected, the first threshold is used to confirm occupancy. When occupancy ends, the second threshold is used to confirm the area is clear. This parameter change eliminates the flickering effect by creating a hysteresis buffer zone between the two threshold values.
Solution Approach 2:
The patent introduces dynamic threshold selection based on the current state of the monitored area. The evaluation unit dynamically switches between the first threshold (for entering occupied state) and the second threshold (for transitioning to free state), making the threshold adaptive rather than static. This dynamic approach prevents rapid state changes while maintaining detection sensitivity.
2Device complexity
If discrete beams are used to scan objects, then the measurement process is simplified, but the measured object dimension fluctuates with distance and lateral position
Solution Approach 1:
The patent uses feedback from multiple discrete beam measurements to determine object presence. The evaluation unit analyzes the pattern of beam intersections and uses the first and second thresholds to interpret this feedback data. This feedback mechanism compensates for the fluctuations caused by discrete beam scanning, maintaining measurement precision while keeping the device relatively simple.
3Area of stationary object
If the sensor detects objects at all distances, then the monitoring coverage is complete, but small objects are detected as interfering objects
Solution Approach 1:
The patent changes the detection parameter from absolute object size to a relative measure based on the number of intersected beams. By using thresholds based on beam intersection counts rather than fixed size values, the system can distinguish between small interfering objects and larger target objects across all distances, maintaining complete monitoring coverage while improving detection accuracy.
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
Ensures robust and reliable detection of object presence by preventing rapid state fluctuations, enhancing stability in monitoring environments like autonomous vehicles.
Implementation Method 1
The transmitter emits signals into the area to be monitored
Implementation Method 2
detection signals, in particular signals which are reflected or remitted in the area to be monitored
Data Source
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AI summary
A sensor for monitoring an area for the presence of at least one object comprises a transmitting device, a receiving device, and an evaluation device. The transmitting device emits signals into the area to be monitored. The receiving device receives detection signals, which include signals reflected or remitted within the area to be monitored. The evaluation device is configured to determine, based on the detection signals, at least one measured quantity that is related to at least one dimension of an object in the area to be monitored.The evaluation unit is further designed to determine and output an occupied state of the monitored area if at least one measured variable is greater than an entry threshold, and to determine and output a free state of the monitored area if at least one measured variable is less than an exit threshold. The exit threshold differs from the entry threshold.