Parallel Robot Wrist Drive Nested Holder Transmission
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Solution Overview
Problem
Conventional parallel robots face restrictions in operational space and suffer from reduced stiffness and accuracy due to the configuration of auxiliary drive mechanisms, which can interfere with universal joints and generate inertial forces affecting motion.
Innovation Solution
A parallel robot with a wrist-section drive mechanism featuring a triply nested holder assembly and a monolithic rod-shaped transmission member that moves linearly in a rotationally restrained state, integrated with a universal joint, allowing for enhanced torque transmission and improved stiffness and accuracy without restricting the operational space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a telescopic configuration with tubular hard bushing is used for the transmission member, then the transmission member can elongate and contract smoothly, but the linear bearing component interferes with universal joint components, restricting the operational space
Solution Approach 1:
The patent applies nesting by placing the transmission member inside the holder assembly, with the transmission member being received within the hollow cylindrical structure of the holder. This nested configuration allows the transmission member to elongate and contract smoothly while being contained within the holder's internal space, preventing interference with universal joint components and maintaining full operational space.
2Force
If the diameter of rod-shaped elements is reduced to inhibit inertial force, then inertial force is reduced, but the stiffness and operational accuracy of the transmission member are degraded
Solution Approach 1:
The patent employs composite materials by constructing the transmission member from a lightweight material such as aluminum alloy or carbon fiber reinforced plastic (CFRP). These composite materials provide a high strength-to-weight ratio, enabling the transmission member to maintain sufficient stiffness and operational accuracy while having reduced mass that minimizes inertial forces affecting the movable section's motion.
3Adaptability or versatility
If a telescopic configuration is used for the transmission member, then the transmission member can follow the three-axis translational motion, but the configuration generates inertial forces that affect the movable section's motion
Solution Approach 1:
The patent replaces the conventional telescopic mechanical configuration with a linearly-movable transmission member system where the transmission member moves linearly along the holder's axis while being rotationally restrained. This substitution eliminates the complex telescopic joint mechanisms that generate inertial forces, while the linear motion capability allows the transmission member to effectively follow the three-axis translational motion of the movable section.
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 enables reliable torque transmission and precise control of tool orientation across the entire operational space, maintaining high stiffness and accuracy while minimizing inertial forces' impact on the movable section's motion.
Implementation Method 1
a rod-shaped transmission member received in the inner holder and linearly movable in a rotationally restrained state along a linear-motion axis orthogonal to the third rotation axis
Implementation Method 2
the rod-shaped transmission member being connected, at one end thereof spaced from the inner holder, to the wrist section through a universal joint
Implementation Method 3
a rod-shaped transmission member received in the inner holder and linearly movable in a rotationally restrained state along a linear-motion axis orthogonal to the third rotation axis
Data Source
AI summary
A parallel robot including a movable-section drive mechanism having a parallel mechanism configuration and operating to allow a movable section to perform a three-axis translational motion with respect to a base section; and a wrist-section drive mechanism operating to allow a wrist section to perform a rotational motion with respect to the movable section. The wrist-section drive mechanism includes a hollow outer holder connected to the base section rotatably about a first rotation axis; a hollow intermediate holder provided in the outer holder rotatably about a second rotation axis orthogonal to the first axis; a hollow inner holder provided inside the intermediate holder rotatably about a third rotation axis orthogonal to the second axis; a prime mover driving the outer holder to rotate about the first axis; and a transmission member received in the inner holder and linearly movable in a rotationally restrained state along a linear-motion axis orthogonal to the third axis, and connected at one end spaced from the inner holder to the wrist section through a universal joint. The transmission member operates to transmit a rotation of the outer holder about the first axis to the wrist section, and to allow the wrist section to perform a rotational motion about a fourth rotation axis orthogonal to the third axis.