Wearable Power Tool Protection for 3D Limb Proximity Monitoring
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Solution Overview
Problem
Existing power tool operator protection systems are not efficient, accurate, or reliable in preventing injuries from handheld power tools, particularly chainsaws, as they fail to effectively monitor the distance and motion of the tool's working implement relative to the operator's body.
Innovation Solution
A power tool operator protection system that includes wearable position sensors and a power tool position sensor, processing equipment that generates a model of the operator's posture and associates limbs with protection volumes, determining the position and motion of the tool's working implement to generate a protection signal when imminent danger is detected, which can alert the user or activate safety functions to prevent accidents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple distance threshold monitoring is used, then device complexity is reduced, but measurement precision and reliability of injury prevention deteriorate
Solution Approach 1:
The system divides the operator's body into multiple segments by placing wearable position sensors on different body parts (head, torso, arms, legs). Each sensor independently tracks position, and the processing equipment reconstructs the full body posture by combining these segmented data points, achieving precise 3D posture modeling without requiring a single complex sensor system
Solution Approach 2:
The system transitions from simple 1D distance threshold monitoring to 3D spatial monitoring by using multiple position sensors that track x, y, z coordinates. This dimensional expansion enables accurate reconstruction of operator posture and working implement position in three-dimensional space, significantly improving measurement precision while maintaining manageable device complexity through modular sensor placement
2Reliability
If protection signal is generated only when working implement enters protection volume, then false alarms are reduced, but response time for preventing injury is delayed
Solution Approach 1:
The system performs preliminary action by continuously monitoring the position and motion velocity of the working implement relative to the protection volume. When the implement approaches the protection volume boundary or moves toward it with dangerous velocity, the system proactively generates a protection signal before actual contact occurs. This advance warning mechanism provides critical response time while maintaining high reliability by using multiple criteria (position + velocity) to reduce false alarms
3Ease of operation
If fixed safety distance is used, then ease of operation is improved, but adaptability to different operating conditions deteriorates
Solution Approach 1:
The system implements dynamic safety distances that automatically adjust based on real-time operating conditions. The processing equipment continuously calculates the velocity of the working implement and the operator's posture, then dynamically modifies the protection volume boundaries and alarm thresholds. For example, when the implement moves slowly and the operator maintains a stable posture, the system allows smaller safety margins, enabling closer work. When velocity increases or posture becomes unstable, the system automatically expands protection volumes, providing adaptability without complicating operator interaction
Data Source
AI summary
A power tool operator protection system comprises a plurality of wearable position sensors configured to be worn by an operator of a handheld power tool; a power tool position sensor configured to detect the position of a handheld power tool; and processing equipment configured to generate a model of the operator based on the mutual positions of the respective wearable sensors relative to each other, the mutual positions defining the operator's posture; associate each of a plurality of limbs (32a-g) of the operator with a respective protection volume (30a-g); and based on the position and/or motion of the power tool in relation to the protection volume (30a-g) indicating an imminent danger that the working implement enters a protection volume (30a-g), generate a protection signal.