Work Machine Safety Device with Timed Sensor-Change Inhibition
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Solution Overview
Problem
Existing safety control systems for work machines, such as hydraulic excavators, are unstable due to unreliable position information from sensors like infrared depth sensors or cameras, leading to temporary non-detection or fluctuation in detection results, which can cause unstable safety controls.
Innovation Solution
A safety device that periodically acquires position information and inhibits changes in safety control when certain conditions are met, allowing control changes only after a predetermined time or number of acquisitions, ensuring stability by relying on previous reliable information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If safety control is continuously adjusted in response to position information variations, then the system responds quickly to changes, but the control becomes unstable due to unreliable sensor data
Solution Approach 1:
The system performs preliminary action by continuing to execute previous safety control even when current position information suggests a different control should be applied. This is implemented through the control change inhibition mechanism that prevents immediate control changes when position information is considered unreliable, thereby maintaining stability while allowing eventual updates when confidence is restored.
Solution Approach 2:
The system applies beforehand cushioning by introducing a inhibition period that cushions against the harmful effects of unreliable position information. During this period, the system cushions the control output by maintaining previous control values rather than immediately responding to potentially erroneous sensor data, thus preventing instability while preserving responsiveness when data becomes reliable.
2Adaptability or versatility
If the system frequently updates safety control based on new position information, then adaptability improves, but unnecessary adjustments occur due to temporary non-detection or fluctuation
Solution Approach 1:
The system maintains preliminary action by holding onto previous control decisions until sufficient reliable information accumulates. The inhibition period acts as a threshold that must be overcome before control changes are permitted, preventing unnecessary adjustments during temporary detection failures or fluctuations while still allowing adaptability when genuine position changes occur and the inhibition period expires.
3Difficulty of detecting and measuring
If position information from sensors is used for safety control, then detection capability is achieved, but measurement errors and external factors cause unstable detection results
Solution Approach 1:
The system applies beforehand cushioning by introducing a temporal filter through the inhibition period that cushions against measurement errors from sensors. During this period, the system cushions the impact of erroneous position information by maintaining previous control values, thereby compensating for sensor inaccuracies caused by external factors like vibration or temporary non-detection without requiring complex error correction mechanisms.
Data Source
AI summary
A safety device is capable of stably performing safety control for a work machine. The safety device comprises a position information acquisition part and a control part. The position information acquisition part periodically acquires position information on a position of a detection object around the work machine. The control part performs the safety control corresponding to current information when the current information is varied from previous information in a direction of approaching the work machine, executes a control change inhibition of inhibiting the safety control from being changed in response to the variation in the position information when a change inhibition condition including that the current information is varied from the previous information in a direction of separating from the work machine is satisfied, and releases the control change inhibition when a predetermined time has elapsed after the start of the control change inhibition.