Variable Thickness Torque Transmission Bands for Robotic Arm Stiffness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The increasing size of semiconductor substrates leads to longer robotic arms, which results in longer metal bands for torque transmission, causing low natural frequencies and performance issues due to low axial stiffness, making servo motor tuning difficult and affecting throughput.
Innovation Solution
The use of torque transmission bands with variable thickness, where certain segments have increased lateral thickness to enhance stiffness, while maintaining flexibility at pulley interfaces, to improve the natural frequency and performance of robotic arms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal bands are made thin to minimize bending stress and maintain functional lifetime, then reliability is improved, but axial stiffness decreases resulting in low natural frequencies
Solution Approach 1:
The patent applies local quality by creating a metal band with non-uniform thickness: the band is thinner in regions subject to bending stress (to maintain flexibility and functional lifetime) and thicker in regions requiring axial stiffness (to improve natural frequency and reduce vibrations). This localized variation in thickness allows each section of the band to be optimized for its specific mechanical requirements.
2Adaptability or versatility
If length of robotic arms is increased to accommodate larger semiconductor substrates, then adaptability is improved, but natural frequency of metal bands decreases making servo motor tuning difficult
Solution Approach 1:
The patent changes the physical parameters of the metal band by varying its thickness along its length. This parameter modification increases the axial stiffness of the band, which in turn raises the natural frequency of the drive system. The higher natural frequency allows servo motors to be tuned more easily and achieves better performance without requiring shorter arm lengths.
3Weight of moving object
If cross sectional area of metal bands is kept small, then weight is reduced, but axial stiffness decreases resulting in long settling times
Solution Approach 1:
The patent implements local quality by concentrating increased thickness (and thus increased stiffness) only in specific sections of the metal band where axial stiffness is most needed, rather than uniformly increasing the thickness throughout. This localized reinforcement increases stiffness and reduces settling time while minimizing the overall weight increase of the band.
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A substrate processing apparatus comprising a transport arm having serially connected arm links, at least one of the arm links having a predetermined arm link height, at least a first pulley and a second pulley, where the second pulley is fixed to an arm link of the serially connected arm links, and at least one torque transmission band extending longitudinally between and coupled to each of the first pulley and the second pulley, the at least one torque transmission band having a corresponding band height for the predetermined arm link height and a variable lateral thickness such that the at least one torque transmission band includes a segment of laterally increased cross section for the corresponding band height.