Robotic Gripper Brake Control for Fast Closing and Slip Detection
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Solution Overview
Problem
Robotic grippers face challenges in achieving high closing speeds without excessive peak force, early braking mechanism decay, complex user training, and vulnerability to data cable damage, which can lead to object slipping and loss.
Innovation Solution
A robotic gripper design featuring a DC motor, reduction gear mechanism, and a backdrivable mechanism that allows for controlled force application, object slip detection, and reduced cabling through a connector system, enabling efficient object handling and reduced motor overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gripper closes at higher speed, then productivity is improved, but the peak force becomes much higher than the desired pinch force which could damage the object
Solution Approach 1:
The gripper employs dynamic control of the motor during the closing operation. The motor is accelerated to a speed higher than needed for the final closing speed, then rapidly decelerated upon object contact. This dynamic approach allows the gripper to achieve high closing speeds while the controlled deceleration ensures the peak force remains within safe limits (less than 60% greater than holding force).
Solution Approach 2:
The system changes the motor speed parameter dynamically during operation. The motor is driven at varying speeds - higher during approach and closing, then reduced upon contact. This parameter change allows the gripper to optimize both closing speed and force application, resolving the contradiction between productivity and object safety.
2Force
If the motor is engaged at full capacity to hold the object, then the holding force is sufficient, but the motor overheats
Solution Approach 1:
The braking mechanism serves a dual function: it rapidly stops the motor during closing operations and also maintains holding force without requiring continuous motor engagement. This self-service approach allows the system to use the brake for both stopping and holding, eliminating the need for the motor to run continuously at full capacity and preventing overheating.
Solution Approach 2:
The holding function is extracted from the motor and transferred to the braking mechanism. Instead of the motor continuously providing holding force (which causes overheating), the brake takes over this function after the closing operation is complete. This separation of functions allows the motor to be disengaged during holding, preventing thermal issues.
3Speed
If a traditional braking mechanism is used to stop the motor, then the motor can be stopped, but the brake has a fall or decay time before engagement which delays the stopping
Solution Approach 1:
The braking mechanism is pre-positioned and pre-loaded during the motor acceleration phase. As the motor approaches its target speed, the brake is already in place and ready for immediate engagement. This preliminary preparation eliminates the fall or decay time that would otherwise delay brake engagement, allowing for rapid stopping when object contact is detected.
Solution Approach 2:
The braking mechanism maintains continuous readiness throughout the closing operation. Rather than engaging the brake from a neutral state, the system keeps the brake in a pre-charged, ready-to-engage state throughout the approach and closing phases. This continuous preparation ensures immediate brake response when needed, eliminating engagement delays.
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 gripper achieves high closing speeds with forces close to the holding force, detects object slipping, simplifies user training, and minimizes data cable damage, ensuring secure object handling and extended motor life.
Implementation Method 1
DC motor
Implementation Method 2
reduction gear mechanism
Implementation Method 3
brake
Data Source
AI summary
In one aspect, the present disclosure provides a robot gripper with a closing mechanism that while providing a desirable closing speed avoids exerting a force on the rigid object which is greater than the holding force required to hold the rigid object in the gripper. In another aspect, the present invention provides a robot gripper capable of detecting a slip or loss of an object held by the gripper. In an alternative aspect, the present invention provides a robot gripper capable of being hand guided. In another aspect, the invention provides a robot gripper brake drive circuit with faster operation. In one other aspect, the invention provides a connector for connecting a robot end effector to a robot arm with an adjustable cable.