Parallel Robot Kinematic Chains for Motion Stability
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Solution Overview
Problem
Parallel robots with two or three degrees of freedom often exhibit low motion stability substantially perpendicular to their movable plane, limiting their effectiveness in tasks requiring more complex movements.
Innovation Solution
The design incorporates a base plate with two first actuators and a second actuator, connected by kinematic chains with rotating portions and transmission bars, which enhance stability by allowing simultaneous rotation of driving bar assemblies and limiting self-rotation of the mobile platform, thereby increasing positioning precision and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a parallel robot uses a simple structure with two or three degrees of freedom, then the robot achieves simplicity, lower cost, and higher speed, but the robot exhibits low motion stability substantially perpendicular to the movable plane
Solution Approach 1:
The patent introduces a second degree of freedom that rotates substantially perpendicular to the movable plane of the kinematic chains. This adds a new dimensional capability to the robot, transforming it from a planar 2-DOF system to a spatial 3-DOF system, thereby improving motion stability perpendicular to the original movable plane while maintaining the simplicity of the parallel robot architecture
2Adaptability or versatility
If the parallel robot allows free rotation of the mobile platform, then the robot achieves greater versatility in movement, but the robot loses positioning precision and structural stability
Solution Approach 1:
The patent applies different rotational constraints to different parts of the mobile platform. Specifically, the first degree of freedom allows rotation within the movable plane for versatile positioning, while the second degree of freedom controls rotation perpendicular to the movable plane for stability. This localized differentiation of rotational properties enables both versatility and precision simultaneously
3Productivity
If the parallel robot uses only two actuators for simple tasks, then the robot achieves cost-effectiveness and speed, but the robot cannot perform complex tasks requiring higher stability
Solution Approach 1:
The patent implements a dynamic actuation system where two actuators control the mobile platform's position and orientation within the movable plane, while a third actuator dynamically controls the rotation perpendicular to the movable plane. This dynamic configuration allows the robot to maintain high speed for simple tasks while providing the additional stability control needed for complex tasks
Data Source
AI summary
A parallel robot includes a base plate, two first actuators located on the base plate, a mobile platform, and two kinematic chains respectively interconnecting the base plate and the mobile platform. Each kinematic chain includes a driving bar assembly and a driven bar assembly. The driving bar assembly is connected to one of two first actuators. The driving bar includes two substantially parallel first transmission bars. Each of the first transmission bars includes a rotating portion rotatably connected to the base plate. The driven bar assembly interconnects the driving bar assembly and the mobile platform. Each of the two first actuators rotates two rotating portions of the two first transmission bars in the same direction simultaneously.