Dual-Actuator Shape Measurement Apparatus for Stepped Surfaces
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Solution Overview
Problem
Conventional shape measuring devices face issues with stylus breakage and unstable movement when measuring sharp-stepped objects due to sudden changes in current direction and resonance-induced vibrations, leading to errors and damage.
Innovation Solution
A shape measurement apparatus with a dual-actuator system, where the upper and lower actuators apply current in opposite directions and adjust current intensity to control the stylus's movement direction and force, preventing sudden direction changes and resonance, thus stabilizing the stylus on stepped faces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single coil actuator is used to control stylus movement, then the device complexity is reduced, but the stylus breaks easily when encountering stepped faces due to sudden direction changes
Solution Approach 1:
The single coil actuator is segmented into two separate coils: a first coil for controlling downward movement and a second coil for controlling upward movement. This segmentation allows independent control of movement directions, preventing sudden direction changes that cause stylus breakage while maintaining relatively simple device structure.
2Measurement precision
If PID control with differential control is used for precise motion control, then measurement precision is improved, but resonance vibrations occur causing arm shaking and measurement errors
Solution Approach 1:
The control system is segmented into two independent control channels: one for the first coil (downward movement) and one for the second coil (upward movement). This segmentation eliminates the differential control mechanism that generates resonance, while still achieving precise motion control through independent PID control of each coil.
3Reliability
If current direction of the coil is suddenly differentiated to prevent stylus fall, then stylus stability is improved, but the arm moves severely up and down like a seesaw
Solution Approach 1:
The actuator is segmented into two independent coils that can operate separately. When the stylus approaches a stepped face, the first coil can be deactivated and the second coil activated smoothly, avoiding sudden current direction changes that cause seesaw motion while maintaining stylus position control.
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
The dual-actuator system effectively prevents stylus fall and damage by controlling movement and force with precise current adjustments, ensuring stable measurements without sudden direction changes or resonance-induced vibrations.
Implementation Method 1
When current is applied in clockwise direction to the coil 17c in this state, the coil 17c moves upward. The base plate 16 is coupled to the coil 17c and, when the base plate 16 moves upward, the stylus 11 is directed downward about the pivot 15.
Implementation Method 2
the actuator 17 includes a magnet 17b above and below the support plate 17a, as well as a coil 17c to surround the outside of the support plate 17a
Data Source
AI summary
The present invention relates to a shape measurement apparatus comprising: a driving body 130; a measurement arm part 110 having a stylus 111 coming into contact with an object to be measured, and an arm 113 for supporting the stylus 111 so that the stylus 111 comes into contact with the object to be measured; a measurement arm support part 120 coupled to an end of the arm 113; a pivot 121 for rotatably supporting the measurement arm support part 120 with respect to the driving body 130; and an actuator part 140 for controlling the measurement arm support part 120 to rotate up and down with respect to the pivot 121 so that the stylus 111 moves along the object to be measured. The actuator part 140 comprises: a casing 141 partitioned into an upper space and a lower space by a partition wall 141a; an arm coupling base 142 for connecting the casing and the measuring arm support part 120; an upper actuator 143 provided in the upper space; and a lower actuator 145 provided in the lower space, wherein the upper actuator and the lower actuator 145 each comprise: magnetic coupling plates 143a, 145a; first magnets 143b, 145b provided in an upper portion of the magnetic coupling plates 143a, 145a; second magnets 143c, 145c provided in a lower portion of the magnetic coupling plates 143a, 145a; and coils 143d, 145d coupled to the arm coupling base 142 and surrounding the magnetic coupling plates 143a, 145a.