Lockable Compliant End Effector for Workpiece Deformation
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Solution Overview
Problem
Existing robotic systems face challenges in efficiently and accurately performing forming and assembly operations involving dimensional changes of gripped items, particularly in low-volume production scenarios, due to the need for costly and complex tools and the difficulty in handling deformable materials.
Innovation Solution
A robotic system with a lockable end effector featuring arms with flexible joints that can alternate between locked and unlocked states, controlled by a controller to maintain grip during deformation and relieve forces, using sensors and vision systems to manage joint unlocking based on force and deformation thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a robotic system uses a rigid gripper to hold a workpiece during forming operations, then the gripper can maintain a firm grip, but the system cannot accommodate dimensional changes in the workpiece without applying unwanted forces
Solution Approach 1:
The joint assembly transitions from a locked rigid state to an unlocked flexible state, allowing the arm to dynamically adapt its stiffness based on the forming operation requirements. This enables the system to maintain grip stability during transport but accommodate dimensional changes during forming without applying unwanted forces.
Solution Approach 2:
The compliance level of the arm is changed by unlocking the lock mechanism in the joint assembly, allowing the arm to deform elastically to accommodate workpiece dimensional changes. This parameter change enables the system to adapt to varying workpiece dimensions while maintaining a reliable grip.
2Manufacturing precision
If a robotic system uses fixed geometric-specific tools for forming operations, then the forming operations can be performed with high precision, but the development lead-time and cost increase significantly
Solution Approach 1:
The robotic system with lockable compliance arms serves as a universal forming system that can handle various workpiece geometries and forming operations without requiring geometric-specific tools. The same robotic system with adjusted compliance parameters can perform different forming operations, eliminating the need for multiple specialized tooling sets.
Solution Approach 2:
Instead of using fixed geometric-specific tools, the system changes operational parameters by adjusting the compliance level of the arms through locking and unlocking mechanisms. This allows a single universal system to accommodate different forming operations by modifying compliance parameters rather than changing physical tooling geometry.
3Adaptability or versatility
If a robotic system repeatedly engages and releases the workpiece during forming operations, then the system can accommodate dimensional changes, but the operation time and productivity decrease
Solution Approach 1:
The robotic system maintains continuous engagement with the workpiece throughout the forming operation by keeping the gripper closed and the arm in a flexible state. This eliminates the need to repeatedly engage and release the workpiece, as the system continuously adapts to dimensional changes while maintaining grip, thereby improving productivity.
Solution Approach 2:
The arm transitions to a flexible dynamic state during forming operations, allowing continuous adaptation to workpiece dimensional changes without repeated engagement cycles. This dynamic flexibility enables the system to maintain useful action continuously rather than cycling through engage-release sequences.
4Stability of the object's composition
If the robotic arm locks the joint assembly to maintain position, then the arm provides stable support, but forces build up in the arm during workpiece deformation that can cause damage
Solution Approach 1:
The joint assembly dynamically switches between locked and unlocked states based on the forming operation phase. During positioning, the joint is locked to provide stability. During forming, the joint is unlocked to allow flexibility and prevent force buildup. This dynamic state change resolves the contradiction between stability and strength.
Solution Approach 2:
The system proactively unlocks the joint assembly before significant force buildup occurs during forming operations. This beforehand action prevents excessive forces from developing in the arm, cushioning against potential damage before it occurs rather than reacting after forces have built up.
Data Source
AI summary
Robotic systems and methods are provided with an end effector having lockable compliance. A robotic system for manipulating a workpiece includes an arm having a pair of sections connected by a joint assembly, with a lock disposed in the joint assembly. A gripper is connected on the arm and is configured to alternately grip and release the workpiece. A controller operates the lock to alternately lock and unlock the joint assembly. The gripper holds the workpiece during a deformation of the workpiece, while the controller may unlock the lock to allow movement of the joint assembly to relieve forces on the arm arising during a deformation of the workpiece.