Armrest Sensor Control Enablement for Safer Work Machines
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Solution Overview
Problem
Existing work machines face challenges in comfortably and reliably enabling and disabling user controls to prevent inadvertent operation, as users may find it uncomfortable to maintain the correct hand or body position to activate sensors for extended periods, leading to potential fatigue and reduced safety.
Innovation Solution
A work machine with an armrest sensor that enables control responsive to the application of the operator's arm and disables it upon removal, combined with a seat sensor that ensures the operator is seated, allowing for comfortable and safe operation by enabling the control only when the operator is in the working position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensors are arranged to detect hand or body position to prevent inadvertent operation, then safety is improved, but operator comfort deteriorates due to the need to maintain correct position throughout work cycle
Solution Approach 1:
The patent extracts the safety function from continuous hand-position monitoring and relocates it to armrest presence detection. The sensor is moved from the control lever to the armrest, detecting only whether the operator's arm is present rather than continuously monitoring hand position. This resolves the contradiction by maintaining safety through armrest detection while freeing the operator from maintaining specific hand positions during operation.
Solution Approach 2:
The armrest serves as an intermediary element between the operator and the control system. Instead of directly monitoring the operator's hand or body position, the system uses the armrest as a mediator - its presence indicates operator presence and enables control, while its absence disables control. This intermediary approach maintains safety without requiring continuous operator positioning.
2Reliability
If sensors continuously monitor operator position to enable control, then safety is improved, but operator fatigue increases due to maintaining fixed position
Solution Approach 1:
The patent extracts continuous position monitoring from the safety function and replaces it with simple armrest presence detection. The sensor only needs to detect whether the armrest is occupied, not the continuous position of the operator's hand or body. This reduces the monitoring burden while maintaining safety, allowing operators to move freely during operation without causing fatigue.
Solution Approach 2:
The system applies partial monitoring - instead of continuously tracking full operator position, it only monitors the binary state of armrest occupancy. This partial action is sufficient for safety purposes while dramatically reducing the operational burden on the operator, enabling longer work durations without fatigue.
3Ease of operation
If armrest sensor enables control upon arm application, then operator comfort is improved, but risk of inadvertent operation increases if armrest is accidentally touched
Solution Approach 1:
The patent merges multiple safety functions into a single integrated control enablement system. The armrest sensor simultaneously performs: (1) operator presence detection, (2) control enablement/disabling, and (3) inadvertent operation prevention. By combining these functions and requiring the armrest to be deliberately occupied for a sustained period to enable control, the system achieves both comfort and safety without requiring separate mechanisms.
Solution Approach 2:
The system requires preliminary action - the operator must deliberately place their arm on the armrest and maintain it there for a predetermined time period before control is enabled. This preliminary action distinguishes intentional operator presence from accidental armrest contact, preventing inadvertent operation while maintaining operator comfort during normal use.
Data Source
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AI summary
A work machine (1) comprises an armrest (21) and a user control (12) operable by the user (5) to control tool or machine functions when the user's arm rests on the armrest. An armrest sensor (22) is configured to sense the presence of the user's arm and to disable the control (12) when the user's arm is removed from the armrest (21). The control (12) may be mounted on the armrest (21) and the armrest movable between enabling and disabling positions by the weight of the user's arm. A seat sensor (25) may be configured to disable the control (12) when the user leaves the seated position.