Robotic Gripper Control for Fast Closing and Slip Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Robotic grippers face challenges in closing speed, peak force management, early braking decay, object slipping detection, and cumbersome data connectivity, which affect their efficiency and reliability in handling objects.
Innovation Solution
A robotic gripper design featuring a DC motor, reduction gear mechanism, and a motor drive controller that controls speed and torque to prevent excessive peak force, combined with an object slip detector using an encoder and electrically controllable brake, and a connector for reduced cabling, enabling efficient object handling and data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gripper closes at higher speed, then productivity is improved, but the peak force becomes excessively high which could damage the object
Solution Approach 1:
The motor drive controller implements periodic action by controlling the motor to operate in different phases: during normal closing operation, the motor runs at nominal maximum speed for high productivity; when the finger arrests against the object, the motor naturally decelerates to zero speed, creating a periodic cycle of high-speed operation followed by controlled deceleration. This periodic operation pattern allows the system to achieve high closing speeds while limiting peak force through the natural deceleration characteristic of the motor-gear-finger mechanism.
Solution Approach 2:
The system applies parameter changes by utilizing the motor's speed-torque characteristics dynamically. As the motor decelerates from nominal maximum speed to zero upon finger arrest, the torque parameter naturally increases, but the gear mechanism and finger design ensure that the resulting pinch force remains within acceptable limits (less than 60% greater than holding force). This parameter transition from high speed/low torque to low speed/high torque resolves the contradiction between closing speed and peak force.
2Use of energy by moving object
If a brake mechanism is used to hold the object, then energy consumption is reduced, but the brake has a fall or decay time before engagement which affects response
Solution Approach 1:
The electrically controllable brake implements preliminary action by being pre-positioned and ready for immediate engagement. The brake mechanism is designed to transition quickly from the released state to the engaged state when activated, minimizing the fall or decay time. This preliminary preparation allows the brake to engage almost instantaneously when needed, reducing the time loss while still allowing the motor to operate at reduced power during holding phases.
3Measurement precision
If an encoder and brake system are implemented to detect slippage, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The encoder serves multiple functions: it primarily controls the motor position and speed during normal operation, and simultaneously detects slippage by monitoring unexpected position changes when the brake is engaged. This multi-functionality allows the system to achieve precise slippage detection without adding dedicated detection hardware, thereby improving measurement precision while minimizing the increase in device complexity.
Solution Approach 2:
The system implements feedback by continuously monitoring the encoder position data and comparing it against expected positions during braking operation. When slippage occurs, the encoder detects the position discrepancy and provides feedback to the control system, enabling accurate slippage detection. This feedback mechanism achieves high measurement precision using the existing encoder infrastructure rather than requiring completely separate detection systems.
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 controlled closing speeds without excessive force, detects object slipping, reduces braking decay, and minimizes data cable damage, enhancing object handling and system reliability.
Implementation Method 1
DC motor
Implementation Method 2
reduction gear mechanism
Implementation Method 3
electrically controllable brake
Implementation Method 4
encoder reading a position
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.