Parallel Link Mechanism for Stable Tool-Tip Posture Change
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Solution Overview
Problem
In parallel link mechanisms, the significant movement of the distal end of a tool during posture change is undesirable, leading to increased device size and complex control requirements when the center of rotation is far from the end-effector base.
Innovation Solution
A parallel link mechanism design where the center of rotation of the end-effector base is positioned closer to the tool, with link mechanisms configured such that the axes of rotation intersect at the distal end of the tool, minimizing the movement of the tool's distal end during posture changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the center of rotation is positioned far from the end-effector base, then the end-effector base can tilt significantly to change tool posture, but the distal end of the tool moves significantly which is undesirable
Solution Approach 1:
The invention changes the position parameter of the center of rotation from being far from the end-effector base to being close to or at the distal end of the tool. This parameter change fundamentally alters the relationship between end-effector base tilting and distal end movement, allowing posture change with minimal distal end displacement.
Solution Approach 2:
The invention introduces a new spatial dimension by positioning the center of rotation at the distal end of the tool rather than at the end-effector base. This dimensional repositioning creates a spherical workspace where the distal end remains relatively stationary while the end-effector base rotates around it, solving the contradiction between posture flexibility and distal end stability.
2Manufacturing precision
If the center of rotation is positioned close to the distal end of the tool, then the distal end movement is minimized, but the end-effector base tilting range is reduced
Solution Approach 1:
By changing the position parameter of the center of rotation to coincide with or be near the distal end of the tool, the invention achieves high position precision for the distal end while maintaining adequate tilting range through the spherical motion mechanism.
Solution Approach 2:
Instead of having the end-effector base tilt around a distant center of rotation, the invention inverts the approach by having the end-effector base rotate around a center of rotation at the distal end, fundamentally reversing the rotation geometry to achieve both precision and range.
3Manufacturing precision
If another device is added to change the position of the fixed base to achieve distal end fixation, then posture change is possible, but the device size and control complexity increase
Solution Approach 1:
The invention extracts the center of rotation function from the fixed base and relocates it to the distal end of the tool through the link mechanism geometry. This extraction eliminates the need for additional devices to fix the distal end position, as the mechanism inherently provides this function through its spherical motion characteristics.
Solution Approach 2:
The link mechanism is designed to simultaneously achieve multiple functions: changing tool posture, fixing distal end position, and providing spherical motion. This multi-functionality eliminates the need for separate devices, reducing overall system complexity while maintaining position stability.
Data Source
AI summary
A parallel link mechanism includes three or more link mechanisms that couple a fixed base and an end-effector base. The end-effector base has a facing surface facing the fixed base. The link mechanisms each include a proximal-end joint, a proximal link, an intermediate joint, a distal link, and a distal-end joint. The proximal-end joint is rotatably coupled to the fixed base. The proximal link is coupled to the proximal-end joint. The intermediate joint is provided to the proximal link. The distal link is rotatably coupled to the proximal link via the intermediate joint. The distal-end joint rotatably couples the distal link to the end-effector base. The point of intersection at which the extensions of the axes of rotation of the proximal-end joints, the extensions of the axes of rotation of the intermediate joints, and the extensions of the axes of rotation of the distal-end joints intersect is the center of rotation of the end-effector base. The center of rotation of the end-effector base is positioned in a first direction with respect to the facing surface.