Articulated Robot Structure With Base-Mounted Actuator
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Solution Overview
Problem
Multi-axis robots face limitations in speed due to high inertia caused by ball-screw systems and motor placement in their articulated structures, which restricts vertical movement and overall performance.
Innovation Solution
A novel articulated structure with a deformable parallelogram design, featuring a third electric actuator mounted on the base or arm, reduces inertia by eliminating the need for the forearm to move the actuator during pivoting, allowing for high-speed movements with a combination of rotary actuators and 90° angle transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a ball-screw system is used for vertical movement, then the robot can perform vertical plane movements, but the inertia of the articulated structure increases significantly
Solution Approach 1:
The patent extracts the third actuator from the moving forearm and relocates it to the stationary base. This separation removes the actuator's weight from the moving mass, thereby reducing the inertia of the articulated structure while preserving the vertical movement capability through the parallelogram mechanism.
Solution Approach 2:
Instead of mounting the actuator on the moving forearm (conventional approach), the patent inverts the arrangement by mounting it on the stationary base. This inversion allows the actuator to control the parallelogram structure without being part of the moving mass, resolving the contradiction between movement capability and inertia.
2Ease of operation
If the third actuator is mounted on the forearm, then vertical control is achieved, but the inertia of the forearm increases limiting movement speed
Solution Approach 1:
The third actuator is extracted from the forearm assembly and relocated to the base. This extraction eliminates the actuator's contribution to forearm inertia, enabling higher movement speeds while maintaining vertical control through the base-mounted actuator's control of the parallelogram structure.
Solution Approach 2:
The patent inverts the conventional mounting arrangement by placing the actuator on the stationary base rather than on the moving forearm. This inversion achieves vertical control without adding to the moving mass, thereby resolving the speed limitation.
3Ease of operation
If a ball-screw system is used for vertical movement, then vertical positioning is achieved, but the size of the system becomes an impediment
Solution Approach 1:
The patent replaces the conventional ball-screw mechanical system with a parallelogram linkage mechanism controlled by a base-mounted actuator. This substitution achieves vertical positioning through geometric constraints rather than threaded mechanical conversion, resulting in a more compact system without the bulky ball-screw components.
Data Source
AI summary
An articulated structure for a multi-axis robot includes a base having an arm hinged to the base about a first axis and a forearm hinged to the arm about a second axis parallel to the first axis, and wherein the forearm forms a deformable parallelogram structure which includes two connecting rods that are hinged to two plates about respective axes that are perpendicular to the first and second axes. The structure also includes a first electric actuator controlling pivoting of the arm about the first axis, a second electric actuator controlling pivoting of the forearm about the second axis, and a third electric actuator mounted directly on one of the base and the arm for controlling pivoting of one of the connecting rods relative to the plates about the axes that are perpendicular to the first and second axes.