Flexible Shaft Transmission for Accurate Axial Force Sensing
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Solution Overview
Problem
Existing transmission mechanisms in robots using flexible shafts face challenges in accurately measuring axial force due to spurious components from bending and twisting deformations, which affect the accuracy of force control.
Innovation Solution
A transmission mechanism is designed with a flexible shaft, a conversion mechanism, and a blocking device that separates torque and axial force transmission, allowing accurate detection of axial force by blocking the transmission of axial force from the flexible shaft to the input shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a flexible shaft is used to transmit torque to a conversion mechanism, then the robot hand can achieve flexible positioning, but bending and twisting deformation of the flexible shaft generates spurious axial force that degrades measurement accuracy
Solution Approach 1:
The transmission system is segmented into two independent functional paths: one for torque transmission (flexible shaft to input shaft) and one for axial force measurement (input shaft to load sensor). The blocking device creates a mechanical separation that divides the originally coupled transmission path into independent segments, allowing torque and axial force to be handled separately.
Solution Approach 2:
The blocking device acts as an intermediary element between the flexible shaft and the input shaft of the conversion mechanism. It selectively transmits torque while blocking axial force from the flexible shaft, serving as a mediator that filters out the harmful axial force component while preserving the useful torque transmission.
2Extent of automation
If a load sensor is provided to measure axial force at the input shaft, then force control can be implemented, but the measured axial force includes spurious components from the flexible shaft that reduce control accuracy
Solution Approach 1:
The blocking device converts the harmful effect of flexible shaft axial force into a beneficial measurement condition. By blocking the spurious axial force from reaching the input shaft, the load sensor now measures only the true axial force generated by the output member, transforming the previously contaminated measurement into a clean, accurate signal for force control.
3Ease of operation
If the input shaft is supported by a bearing to allow rotation, then the conversion mechanism can operate, but the bearing cannot distinguish between torque-driven rotation and axial force from the flexible shaft
Solution Approach 1:
The blocking device serves as an intermediary that decouples the bearing's rotational function from axial force transmission. It allows the bearing to perform its intended function of supporting rotational motion while preventing the bearing from also supporting axial force from the flexible shaft, thereby isolating the axial force measurement function.
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
Enables precise force control by accurately measuring the axial force of the output member, improving the accuracy of force control in robots.
Implementation Method 1
a screw shaft that forms a part of the input shaft and a nut threading with the screw shaft and forms a part of the output member
Data Source
AI summary
A transmission mechanism configured to be interposed between a drive device and a driven member configured to be driven by a torque outputted by the drive device, the transmission mechanism comprises a flexible shaft having an input end receiving the torque outputted by the drive device, a conversion mechanism having an input shaft supported by a link member via a first bearing in a rotatable but axially immovable manner and configured to receive the torque from the flexible shaft and a converter for converting the torque of the input shaft into an axial force, and a blocking device that allows the transmission of the torque from the flexible shaft to the input shaft but blocks transmission of the axial force from the flexible shaft to the input shaft.