Multi-link Articulated Arm for Surface Roughness Measurement
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Solution Overview
Problem
Conventional coordinate measuring machines struggle to accurately measure the surface roughness of complex workpieces with narrow and angled regions due to their large positioning devices, which often cannot position a stylus instrument or sensor effectively within openings or recesses, leading to reduced measurement accuracy and susceptibility to vibrations.
Innovation Solution
A multi-link articulated arm with a roughness sensor, where the deflection direction is arranged parallel to the third axis of rotation, allowing the sensor to be positioned precisely within complex workpiece geometries without unwanted rotation, and using flexible printed circuits or optical waveguides for signal transfer to maintain high accuracy and reduce electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional coordinate measuring machines use large positioning devices, then they can achieve high measurement accuracy on simple surfaces, but they cannot effectively position sensors within narrow and angled regions of complex workpieces
Solution Approach 1:
The positioning device is segmented into multiple independent rotational axes (first, second, and third axes of rotation) with separate drive mechanisms. This segmentation allows each axis to independently contribute to the sensor's final position, enabling access to complex geometries while maintaining precision through coordinated control of individual segments.
Solution Approach 2:
The invention transitions from conventional linear positioning to multi-axis rotational positioning. By adding rotational degrees of freedom around three different axes, the system gains the ability to reach narrow and angled regions that are inaccessible to traditional linear positioning devices, effectively adding dimensional capability to the positioning approach.
2Adaptability or versatility
If the arm construction is made thin to reach complex geometries, then adaptability improves, but susceptibility to vibrations increases
Solution Approach 1:
The arm construction applies local quality by making different portions of the arm have different thickness characteristics. The arm can be thinner in regions requiring flexibility to reach complex geometries while maintaining adequate thickness in regions requiring vibration resistance, optimizing both adaptability and stability locally throughout the structure.
Solution Approach 2:
The arm may utilize composite materials that combine high strength-to-weight ratio properties, allowing the construction to be sufficiently thin to access narrow regions while maintaining rigidity and vibration resistance through the inherent properties of the composite material structure.
3Ease of operation
If the deflection direction is not aligned with the third axis of rotation, then the sensor can be positioned flexibly, but unwanted rotations occur during contact
Solution Approach 1:
The deflection direction is pre-aligned with the third axis of rotation to prevent unwanted rotations before they can occur during measurement. This preliminary alignment ensures that contact forces act along the intended measurement axis, counteracting any tendency for the sensor to rotate unintentionally during the measurement process.
Solution Approach 2:
The invention changes the critical parameter of deflection direction alignment to be parallel with the third axis of rotation. This parameter change optimizes the measurement configuration by ensuring that the sensing element's deflection occurs along a stable rotational axis, preventing unwanted rotations while maintaining positioning flexibility through the multi-axis arm structure.
4Area of stationary object
If conventional sensors are used in complex geometries, then measurement coverage is limited, but measurement accuracy is maintained in accessible regions
Solution Approach 1:
The measuring system transitions from static positioning to dynamic multi-axis rotational positioning. The arm can dynamically adjust its orientation and position through coordinated rotation around three axes, allowing the sensor to access and measure surfaces in complex geometries that would be inaccessible to conventional fixed or linearly-positioned sensors, thereby expanding measurement coverage while maintaining accuracy.
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 configuration enhances measurement accuracy by preventing unwanted rotations during contact and reduces susceptibility to vibrations, enabling precise surface roughness measurements in complex workpiece geometries while maintaining high rigidity and minimizing signal interference.
Implementation Method 1
The roughness sensor (44) has a sensing element (60) that is linearly displaceable along an advance direction (V) and elastically deflectable along a deflection direction (D)
Implementation Method 2
using flexible printed circuits or optical waveguides for signal transfer to maintain high accuracy and reduce electromagnetic interference
Data Source
AI summary
An apparatus for measuring a surface of a workpiece has a multi-link articulated arm and a roughness sensor carried by the arm, which includes a sensing element linearly displaceable along an advance direction and elastically deflectable along a deflection direction, and which has a coupling link to connect it to a movable carrier of a coordinate measuring apparatus or of a robot. A first arm portion is rotatable relative to the coupling link about a first axis of rotation. A second arm portion is rotatable relative to the first arm portion about a second axis of rotation and arranged between the first and third arm portion which is rotatable relative to the second arm portion about a third axis of rotation, and to which the roughness sensor is fastened. The deflection direction is arranged parallel to the third axis while the sensing element is displaced linearly along the advance direction.