Adaptive Screw Driving Tool Using Relative Displacement Control
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Solution Overview
Problem
Automated screwdriver systems face inefficiencies due to material and tool variations, leading to decreased throughput as they struggle to accurately drive screws into workpieces with inconsistent thickness and threading, and require constant torque monitoring.
Innovation Solution
A screw driving tool with a rotatable bit and independently movable finder, using position detectors to measure relative displacement, drives screws in phases at different speeds, updating target displacement values based on final measurements to adapt to material and tool variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the screw is driven at a first low speed while monitoring torque and thereafter lowering the speed as the target torque is approached, then the torque control precision is improved, but the throughput of the screw driving system significantly decreases
Solution Approach 1:
The patent changes the control parameter from torque to relative displacement. By measuring the relative displacement between the bit and finder components, the system determines when to transition between driving phases without relying on torque monitoring, thereby maintaining precision while enabling higher speeds and improved throughput
Solution Approach 2:
The patent replaces the torque monitoring mechanism with a position detection mechanism. The position detector measures relative displacement between components, substituting the mechanical torque sensing system with a positional measurement system that allows for faster, more reliable control
2Device complexity
If material variations (thickness and threading) are not accounted for, then the screw driving process is simpler, but the reliability of the screw driving tool decreases
Solution Approach 1:
The system performs self-calibration by measuring the final relative displacement after driving a screw and using this information to update the target relative displacement value for subsequent screws. This self-adjusting mechanism accounts for material variations without requiring external intervention or complex setup procedures
Solution Approach 2:
The patent implements a feedback loop where the final relative displacement measurement from each screw driving operation is used to update the target displacement value for the next operation. This feedback mechanism automatically compensates for material and tool variations, improving reliability while maintaining process simplicity
3Device complexity
If tool variations (tolerances in screw driving tool) are not accounted for, then the measurement system is simpler, but the control accuracy across multiple tools decreases
Solution Approach 1:
Each tool performs self-calibration by measuring its own actual displacement characteristics during operation and using this information to adjust its target values. This self-service approach accounts for individual tool tolerances without requiring complex external calibration equipment or systems
Solution Approach 2:
The patent changes from using fixed target torque values to using adaptive target displacement values that are updated based on actual measurements from each tool. This parameter change allows each tool to operate within its own tolerance range while maintaining consistent control accuracy across the entire tool fleet
Data Source
AI summary
A method of driving screws into a workpiece using an automatic screw driving tool having first and second components, the first component including a screw bit. The method may include steps of measuring a relative displacement between the first and second components; driving, in a first phase, a first screw partially into the workpiece at a first speed until a target relative displacement value is reached; after the first phase, driving, in a second phase, the first screw further into the workpiece at a second speed that is different than the first speed; completing the driving process for the first screw; measuring a final relative displacement of the first and second components after the first phase to determine a final relative displacement value, and updating the target relative displacement value based on the final relative displacement value.