Robot Arm With Slaved End-Effector Motion for Faster Wafer Transfer
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Solution Overview
Problem
Existing robotic systems for transporting substrates in clean or vacuum environments, such as semiconductor manufacturing, face challenges in minimizing footprint, optimizing transport times, and enhancing throughput due to limitations in arm design and motion control.
Innovation Solution
A robot arm mechanism with a drive unit featuring multiple coaxial shafts and a multi-link structure, utilizing band arrangements with variable and constant transmission ratios, allows for precise control of end-effector orientation and movement, enabling efficient access to multiple stations with reduced cycle times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a robot arm mechanism with multiple coaxial shafts and band arrangements is used, then end-effector orientation control and access to multiple stations is improved, but device complexity increases
Solution Approach 1:
The patent implements nesting by placing the second drive axis coaxially within the first drive axis, and the third drive axis coaxially within the second drive axis. This nested configuration allows multiple drive axes to occupy the same spatial envelope, reducing the overall footprint while maintaining the capability for complex end-effector orientation control through coordinated rotation of nested axes.
Solution Approach 2:
The band arrangements serve multiple functions: they transmit rotational motion from drive axes to rotary joints, provide variable transmission ratios for optimized motion control, and enable coordinated movement of multiple joints through mechanically coupled pulleys. This multi-functionality reduces the need for separate actuation mechanisms for each joint.
2Loss of time
If variable transmission ratio band arrangements are used, then transport time and cycle time are reduced, but manufacturing precision and control complexity increase
Solution Approach 1:
The patent employs variable transmission ratios in the band arrangements that can be dynamically adjusted based on the robot arm's configuration and task requirements. This dynamic adjustment allows optimization of transport speed during different phases of motion while maintaining precise control through coordinated actuation of the drive axes, resolving the trade-off between speed and precision.
3Area of stationary object
If multiple coaxial drive axes are used, then footprint is minimized, but ease of manufacture and assembly deteriorate
Solution Approach 1:
The patent implements nesting by placing the second drive axis coaxially within the first drive axis, and the third drive axis coaxially within the second drive axis. This nested configuration allows multiple drive axes to occupy the same spatial envelope, reducing the overall footprint while maintaining the capability for complex end-effector orientation control through coordinated rotation of nested axes.
Data Source
AI summary
An apparatus having a drive unit having a first drive axis rotatable about a first axis of rotation and a second drive axis rotatable about a second axis of rotation, the second drive axis being coaxial with and partially within the first drive axis and axially rotatable within the first drive axis. A robot arm has an upper arm connected to the drive unit at the first drive axis, a forearm coupled to the upper arm, the forearm being coupled to the upper arm at a first rotary joint and rotatable about the first rotary joint, the first rotary joint being actuatable by a first band arrangement coupled to the second drive axis, and an end effector coupled to the forearm, the end effector being coupled to the forearm at a second rotary joint and rotatable about the second rotary joint, the second rotary joint being actuatable by a second band arrangement coupled to the first rotary joint. The second band arrangement is configured to provide a variable transmission ratio.