Power-Assist Joint Lock Control for Stable Workpiece Positioning
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Solution Overview
Problem
Power assist apparatuses face challenges in stabilizing the attitude of workpieces during conveyance, leading to potential contact with attachment subjects and reduced conveyance efficiency, especially when navigating through gaps.
Innovation Solution
A control method and apparatus that detect pressing forces on the workpiece and utilize a dead man switch to determine when to release rotation restrictions on joint portions, ensuring the workpiece's attitude is stabilized during conveyance, allowing for smooth operation and precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the locks on the joint portions are released to allow free positioning adjustment, then the operator can correct the workpiece position freely, but the workpiece may tilt unexpectedly and contact attachment subject members
Solution Approach 1:
The system dynamically switches between locked and unlocked states of the joint portions based on operational phase. During conveyance, joints are locked to maintain stability. During positioning, joints are unlocked to allow adjustment. This dynamic state change resolves the contradiction by providing both stability and adjustability at appropriate times.
Solution Approach 2:
The control device monitors operational status and automatically controls the locking/unlocking of joint portions. The system provides feedback-based automatic control where the state of joint locks is adjusted based on detected pressing forces and operational context, eliminating the need for manual lock management while ensuring both stability and adjustability.
2Reliability
If the operator conveys the workpiece through gaps with careful attitude adjustment, then contact with attachment subject members is prevented, but conveyance efficiency is reduced
Solution Approach 1:
The system performs preliminary locking of joint portions before conveyance through gaps. The control device detects the conveyance operation and automatically locks the joints in advance, preparing the workpiece holding apparatus for stable conveyance without requiring manual adjustment during the critical gap passage.
Solution Approach 2:
The system provides self-service automatic control where the control device autonomously manages the locking/unlocking of joint portions based on detected operational parameters. This eliminates the need for operator intervention in lock management, improving both safety and efficiency.
3Manufacturing precision
If multiple sensors and control mechanisms are added to stabilize workpiece attitude, then positioning accuracy improves, but device complexity increases
Solution Approach 1:
The pressing force detection sensors serve multiple functions: they detect operator gripping actions, monitor workpiece positioning forces, and provide input for automatic joint locking/unlocking control. This multi-functionality reduces the need for separate sensors and control mechanisms, achieving high positioning accuracy without proportionally increasing system complexity.
Solution Approach 2:
The control device integrates multiple control functions into a single unit that manages joint locking, workpiece positioning, and operator interaction. By merging these functions, the system achieves complex automated control while minimizing the number of separate components and control circuits.
Data Source
AI summary
In a control method for a power assist apparatus, a pressing force acting on a workpiece held by a workpiece holding apparatus is detected, a determination is made as to whether or not the detected pressing force exceeds a preset threshold, a determination is made as to whether or not a dead man switch provided on the workpiece holding apparatus is ON, and a determination as to whether or not to release a rotation restriction applied to a joint portion for connecting the workpiece holding apparatus rotatably to an arm is made in accordance with a result of the determination as to whether or not the detected pressing force exceeds the preset threshold and a result of the determination as to whether or not the dead mean switch is ON.