Robot Arm Gravity Compensation With Spring-Pulley Torque Balancing
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Solution Overview
Problem
Industrial articulated robot arms face challenges in designing a driver capable of handling high torque loads due to self-load and workpiece weights, requiring increased power source capacity, and existing gravity compensation mechanisms are limited in practical application.
Innovation Solution
A robot arm design incorporating a gravity compensation mechanism using a rotating body, arm, pulleys, springs, and roller bearings, where strings wound around pulleys compress or stretch springs to compensate for torque loads, allowing the arm to rotate without hindrance and adjust torque loads based on self-load, utilizing timing gears and belts for rotational force transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the capacity of the power source is increased to handle high torque loads from self-load and workpiece weights, then the robot arm can support heavier loads, but the size and complexity of the system increases
Solution Approach 1:
The patent applies gravity compensation mechanisms using springs and counterweights to offset the self-load torque of the robot arm. The compensation mechanism generates an opposing torque that balances the gravitational force on the arm, reducing the net torque requirement for the drive motor and allowing smaller power sources to handle the same effective load capacity.
2Device complexity
If a simple spring-based gravity compensation mechanism is used, then the structure becomes simpler, but the mechanism is limited in practical application and cannot effectively compensate for torque loads
Solution Approach 1:
The patent merges multiple compensation mechanisms into an integrated system that combines springs, counterweights, and pulley systems. This hybrid approach maintains structural simplicity while achieving effective torque compensation across the full range of motion, overcoming the limitations of simple spring-based mechanisms alone.
Solution Approach 2:
The compensation mechanism is designed to be dynamic, with components that adjust their position and force application based on the arm's angle and load conditions. The pulley system and movable counterweights allow the mechanism to adapt its compensation force throughout the rotation range, ensuring reliable performance under varying operational conditions.
3Ease of operation
If roller bearings are added to allow smooth string movement during rotation, then the operation becomes smoother, but the device complexity increases
Solution Approach 1:
Roller bearings are introduced as intermediary elements between the string and the rotating arm components. These bearings act as mediators that facilitate smooth relative motion between the string and the rotating parts, reducing friction and preventing binding while maintaining a relatively simple overall structure.
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 design effectively reduces torque loads by using elastic forces from springs, allowing smooth operation without disturbing the arm's rotation, and adjusts torque loads dynamically, enhancing the arm's operational capacity and reducing the need for increased power source capacity.
Implementation Method 1
a spring embedded in the arm and compressed or stretched in a lengthwise direction of the arm
Implementation Method 2
a plurality of roller bearings arranged to be spaced apart from each other along an outer circumference of the rotating body, rotating about a rotation axis parallel to the central axis of the rotating body, and configured to be in contact with the string
Implementation Method 3
a moving pulley provided at the arm and revolving along a circular track which is concentric with the rotating body; a reference pulley provided at the base and positioned on an inner side with respect to the circular track
Data Source
AI summary
A robot arm including a rotating body connected to a base, an arm rotating about a central axis of the rotating body, a moving pulley provided at the arm and revolving along a circular track which is concentric with the rotating body, a reference pulley provided at the base and positioned on an inner side with respect to the circular track, a spring embedded in the arm and compressed or stretched in a lengthwise direction of the arm, a string compressing the spring and wound around the moving pulley and the reference pulley, and a plurality of roller bearings arranged to be spaced apart from each other along an outer circumference of the rotating body, rotating about a rotation axis parallel to the central axis of the rotating body, and configured to be in contact with the string is provided.