Compliant Robot End-Effector for Bin Picking
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Solution Overview
Problem
Current robot arm gripper designs for bin picking face challenges such as limited compliance with object surfaces, high costs due to expensive force/torque sensors, and inefficient vacuum generation and release, leading to potential damage and increased cycle times.
Innovation Solution
A compact end effector design incorporating an angle compensator, level compensator, proximity sensor, and range sensor, along with a vacuum control system, to provide three degrees of freedom compliance and low-cost position sensing, enabling accurate and efficient object manipulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional gripper with suction cup and long extension rod is used, then the gripper can reach objects in the bin, but the gripper has limited capability to comply with normal direction of the object surface and causes collision and damage
Solution Approach 1:
The patent implements dynamic compliance through a spring mechanism that allows the suction cup to adapt to the object surface normal direction. The spring enables passive compliance in the normal direction while maintaining structural stability, allowing the gripper to conform to varying object surfaces without collision or damage.
Solution Approach 2:
The gripper structure is segmented into multiple functional components: the extension rod for reaching, the spring mechanism for compliance, and the suction cup for contact. This segmentation allows each component to perform its specific function independently, with the spring layer providing normal compliance while the extension rod maintains reaching capability.
2Adaptability or versatility
If a force/torque sensor is used to improve compliance control, then the compliance control is improved, but the cost increases significantly
Solution Approach 1:
The spring mechanism provides passive compliance without requiring active sensing or control systems. The mechanical compliance is inherent in the spring design, eliminating the need for expensive force/torque sensors and complex control algorithms, thereby reducing cost while maintaining compliance control capability.
Solution Approach 2:
The patent replaces active mechanical sensing systems (force/torque sensors) with a passive mechanical compliance mechanism (spring). This substitution achieves compliance control through mechanical design rather than electronic sensing and control, significantly reducing system cost.
3Reliability
If a long air pipe is used to connect vacuum generator, then the vacuum generation capability is sufficient, but the vacuum generation and release takes time and degrades cycle time
Solution Approach 1:
The vacuum generator is extracted from its traditional remote location and integrated directly into the gripper assembly. This eliminates the long air pipe connection, reducing air flow resistance and enabling faster vacuum generation and release, thereby decreasing the cycle time per picking operation while maintaining sufficient vacuum capability.
4Volume of moving object
If a compact end effector design is used, then the space efficiency is improved, but the compliance capability may be reduced
Solution Approach 1:
The spring mechanism is nested within the compact end effector structure, with the suction cup, spring, and vacuum generator integrated in a space-efficient arrangement. The spring compliance mechanism is housed within the gripper body, maintaining compact overall dimensions while preserving the compliance capability through careful spatial integration of components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances compliance and reduces cycle times while lowering costs by using multi-sensor feedback for responsive robotic operations, improving the reliability and efficiency of bin picking tasks without the need for expensive force/torque sensors.
Implementation Method 1
The vacuum is generated when compressed air passes the extension tube, the level compensator and the vacuum generator along the central axis
Implementation Method 2
a proximity sensor attached to the extension tube and configured to determine position of the level compensator
Implementation Method 3
a range sensor attached to the extension tube and configured to determine the position of the level compensator
Implementation Method 4
a vacuum sensor connected to the vacuum control valve and configured to measure vacuum in the vacuum control valve
Data Source
AI summary
An end effector for a robotic arm. The end effector includes an angle compensator for attaching a suction cup, a vacuum control valve, a vacuum generator, a level compensator, and an extension tube which are sequentially connected along a central axis and in fluid communication, and a vacuum sensor connected to the vacuum control valve for measuring vacuum, a proximity sensor attached to the extension tube 121 for determining position of the level compensator. The vacuum is generated when compressed air passes the extension tube, the level compensator and the vacuum generator along the central axis. The level compensator provides compensation along the central axis.