Friction Drive Positioning with Absolute Encoder Feedback
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Solution Overview
Problem
Existing conveyor systems with non-direct drive mechanisms face challenges in achieving precise positioning of workpieces along an assembly line, particularly in systems where direct feedback control is lacking, leading to inaccuracies and longer processing times.
Innovation Solution
A closed loop feedback control system utilizing an optical encoder reader and strip for absolute positioning, integrated with a non-direct friction drive system, allowing for precise control of workpiece carriers to within ±0.4 mm along the path of travel, eliminating the need for additional electrical connections and enabling flexible programmable control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If non-direct friction drive system is used, then flexibility and ease of operation are improved, but positioning precision deteriorates
Solution Approach 1:
The patent implements a closed-loop feedback control system using an absolute encoder strip attached to the workpiece carrier and a stationary encoder reader at the workstation. The encoder provides continuous position feedback to the controller, which adjusts the friction drive to maintain precise positioning accuracy of ±0.4 mm despite the inherent slip characteristics of friction drive mechanisms.
Solution Approach 2:
The patent replaces mechanical direct-drive connections with a friction drive system that uses surface contact between drive rollers and the workpiece carrier. This substitution provides flexibility and ease of operation while the encoder feedback system compensates for the reduced mechanical precision through active control.
2Manufacturing precision
If closed loop feedback control system with encoder is implemented, then positioning precision is improved, but device complexity increases
Solution Approach 1:
The patent introduces an absolute encoder strip as an intermediary element between the workpiece carrier and the control system. This encoder strip acts as a mediator that provides precise position information without requiring complex mechanical linkages or direct electrical connections to the moving carrier, thereby achieving high positioning precision with relatively simple implementation.
Solution Approach 2:
The patent uses an optical encoder strip that creates an optical copy or representation of the physical position of the workpiece carrier. The stationary encoder reader reads patterns on the moving encoder strip, effectively copying position information without requiring physical measurement mechanisms on the carrier itself, thus reducing device complexity.
3Manufacturing precision
If additional electrical connections are added for precise control, then control precision is improved, but device complexity and installation difficulty increase
Solution Approach 1:
The patent replaces electrical connection mechanisms with a mechanical friction drive system combined with optical encoding. The absolute encoder strip and stationary reader provide precise position feedback without requiring electrical connections to the moving workpiece carrier, eliminating the complexity of sliding contacts, brushes, or wireless power transmission systems.
Solution Approach 2:
The encoder strip serves as an intermediary that transfers position information from the moving carrier to the stationary reader without requiring direct electrical or mechanical coupling. This intermediary approach enables precise control while avoiding the complexity of additional electrical connections between moving and stationary components.
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
This solution reduces processing time by approximately 1 second and enhances accuracy to ±0.4 mm, allowing for precise positioning of workpieces without separate lifters, improving accessibility for automated equipment and meeting stringent positioning specifications.
Implementation Method 1
an optical encoder reader fixed at a stationary position at the workstation and operable to read an optical encoder strip securely connected to the movable portion of the transport system
Data Source
AI summary
An apparatus for positioning a workpiece carrier with respect to a workstation can include a workpiece carrier movable relative to the workstation and having an encoder strip, at least one encoder reader located at the workstation for generating a signal in response to interaction with at least one encoder strip, and a drive engaging the workpiece carrier for moving the carrier relative to the workstation, the drive responsive to the signal from the encoder reader. The encoder reader can be selected from a group consisting of an optical encoder reader, a magnetic encoder reader, and any other absolute positioning encoder reader. A closed loop feedback control system can be provided for receiving the signal from the encoder reader, and for generating an output signal in response to the signal from the encoder reader in accordance with a program stored in memory. The encoder reader can be used for generating a signal corresponding to at least one of a position identification signal, a workpiece carrier identification signal, and a workpiece configuration identification signal.