Planar Multi-Joint Robot Arm Balancing Mechanism
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Solution Overview
Problem
Planar multi-joint robot arm systems have a limited lifespan due to unbalanced construction and high mass and inertia, leading to reliability issues, inaccuracies, and increased costs in high-precision applications like semiconductor manufacturing.
Innovation Solution
A balanced design incorporating a double crank-conrod mechanism with a multi-joint arm and reduced mass and inertia, supported at three positions, along with a third driving unit for base platform rotation, reduces frictional and gravitational forces and tilts, enhancing accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional unbalanced product manipulator design is used, then the system can perform repetitive operations, but the mass and inertia are high leading to limited lifespan and reliability issues
Solution Approach 1:
The patent applies counterweight principles by positioning balancing masses at specific locations along the product manipulator arms to offset the gravitational effects and inertial forces. The balancing masses are strategically placed to create counterbalancing moments that reduce the net forces acting on the driving units, thereby extending system lifespan and improving reliability without requiring excessive motor performance.
2Power
If high mass product manipulator is used, then it can handle payloads, but it requires high motor performance increasing costs
Solution Approach 1:
By implementing balancing masses that counteract the gravitational and inertial forces of the high-mass product manipulator, the system reduces the peak power requirements of the motors. This allows the use of smaller, more cost-effective driving units while still maintaining the capability to handle payloads, thereby reducing overall system cost without sacrificing manufacturing capability.
3Manufacturing precision
If unbalanced construction is used, then the system is simpler, but frictional and gravitational forces in joints increase causing inaccuracies
Solution Approach 1:
The patent introduces balancing masses and associated mounting structures that, while adding some complexity to the construction, significantly reduce frictional and gravitational forces in the joints. This results in improved positioning accuracy and reduced position-dependent tilt, making the enhancement in precision worth the moderate increase in construction complexity.
Solution Approach 2:
The balancing masses are positioned to create equipotential conditions in the gravitational field, ensuring that the product manipulator experiences minimal gravitational variation during its range of motion. This reduces position-dependent forces and improves manufacturing precision by maintaining more consistent joint loads throughout the operating envelope.
4Manufacturing precision
If high mass system is used, then it can maintain structural rigidity, but disturbances during movements increase reducing accuracy
Solution Approach 1:
The balancing masses are strategically positioned to counteract not only gravitational forces but also inertial disturbances during acceleration and deceleration phases. By creating counterbalancing moments that oppose the disturbances generated by high-mass components, the system maintains structural rigidity while reducing movement-induced inaccuracies, thereby achieving both stability and precision.
Data Source
AI summary
The invention relates to a planar multi-joint robot arm system. An example of such planar multi-joint robot arm system comprises a base platform having a longitudinal axis, a product manipulator having a longitudinal axis perpendicular to the longitudinal axis of the base platform, a double crank-conrod mechanism consisting of a first crank-conrod link and a second crank-conrod link, wherein both the first and the second crank-conrod links having a crank end connected to the base platform and a conrod end connected to the product manipulator, and as well as a link element linking both crank-conrod joints of the first and the second crank-conrod links, a first driving unit arranged for rotating the crank end of the first crank-conrod link of the double crank-conrod mechanism, a multi-joint arm having first arm end connected to the base platform and a second arm end connected to the product manipulator as well as a second driving unit arranged for rotating the first arm end of the multi-joint arm.Herewith the construction of the product manipulator and the double crank-conrod mechanism has a more balanced design, and as such the mass and inertia of the overall construction are reduced significantly.