Torque-Free Linkage Unit Gravity Compensation
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Solution Overview
Problem
Existing gravity compensation mechanisms for robot manipulators are inefficient due to continuous variations in motor torque requirements, leading to complex calculations and reliability issues, particularly in multi-degree-of-freedom joints, where conventional wire-based systems are prone to damage and increased mass and volume.
Innovation Solution
A multi-degree-of-freedom torque-free linkage device incorporating a slider-crank mechanism and a curved parallelogram unit, which includes counterbalancers and a parallelogram wire, adjusts counterbalancing torque to compensate for gravitational torque across various joints, minimizing unnecessary torque and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a wire-based gravity compensation mechanism is used, then the mechanism can be manufactured in a relatively small volume and weight, but the wire may be damaged over time leading to reduced performance and safety threats
Solution Approach 1:
The patent replaces the durable but complex weight-based counterbalancer with a simpler, potentially replaceable wire mechanism. The wire serves as a tension element that can be easily replaced if damaged, accepting periodic replacement in exchange for initial simplicity and compactness.
Solution Approach 2:
The patent changes the fundamental parameter of the gravity compensation mechanism from mass-based (weights) to tension-based (wires and springs). This parameter change enables a transition from heavy, inertial compensation to lighter, elastic and tensile force-based compensation, achieving compactness while maintaining functionality.
2Reliability
If a weight-based gravity compensation mechanism is used, then the gravitational torque can be compensated, but the entire mass and volume of the mechanical parts increases
Solution Approach 1:
The patent applies counterbalancing through wires and springs that create opposing forces to gravitational torque. Instead of adding mass to counteract weight, the system uses tensile and elastic forces from wires and springs to generate counterbalancing moments, achieving weight compensation without mass increase.
Solution Approach 2:
The patent substitutes the traditional mechanical weight-based counterbalancer system with a wire-and-spring tension system. This replacement eliminates the need for heavy counterweights while achieving the same gravity compensation function through elastic and tensile forces.
3Adaptability or versatility
If the motor torque required to compensate for gravity varies continuously, then the gravity can be compensated at different positions, but a complex dynamic equation is required to calculate the necessary torque
Solution Approach 1:
The wire-based mechanism with springs provides passive, automatic gravity compensation that adapts to different positions without requiring active control or complex calculations. The elastic and tensile forces automatically adjust to maintain balance across the range of motion, eliminating the need for complex dynamic equations.
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 reduces motor load, allows for smaller motor usage, increases durability and reliability, and extends the application range to multi-degree-of-freedom systems, enabling efficient gravity compensation and improved robot performance.
Implementation Method 1
a method of using a compression force and a tensile force of the spring has been proposed. This method employs a spring repulsive force generated when the wire connected to the link stretch or compress the spring at the time of the rotation of the link
Implementation Method 2
an appropriate weight is installed at a side opposite to a point of application of a force in order to maintain the center of gravity and compensate for the equipment's own weight
Data Source
AI summary
The present invention provides a multi-degree of freedom torque-free linkage unit comprising: a root link; a base link; and a first link spaced from a first joint, and comprises a counterbalancer including a first counterbalancer which enables gravity compensation of the first link, and a curved parallelogram unit comprising: a base part location-fixed and arranged at the root link; a first base part rotatably provided to the base link and the first joint formed by the first link, and connected to the first counterbalancer; and a parallelogram transfer part for connecting the base part and the first base part and forming a reference position for gravity compensation of another link connected to the base link by rotating the first base part on the first joint when the base link moves relatively with respect to the root link.