Force Sensor Control Switching to Suppress Overshoot
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Solution Overview
Problem
Existing contour measuring instruments face challenges in minimizing overshoot during contact between a force sensor and a workpiece, leading to potential breakage and inefficiencies in measurement, particularly due to inertia and complex control requirements.
Innovation Solution
A measurement control device with a force sensor, position detector, and moving unit that switches control from position control to force control before contact, allowing precise positioning and force application, reducing overshoot and maintaining measurement efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If position control is used to position the force sensor close to the workpiece, then positioning accuracy is improved, but overshoot occurs during contact leading to potential breakage
Solution Approach 1:
The system performs preliminary positioning using position control to bring the force sensor close to the workpiece, then switches to force control before contact occurs. This preliminary action allows the system to achieve accurate positioning while preventing overshoot by transitioning control modes in advance, thus avoiding breakage during contact.
Solution Approach 2:
The system dynamically switches between position control and force control modes based on the proximity to the workpiece. Position control is used when the sensor is farther away for accurate positioning, while force control is activated when close to the workpiece to prevent overshoot and contact damage, making the control system adaptive to different operational phases.
2Reliability
If force control is applied during contact, then overshoot is reduced, but control complexity increases
Solution Approach 1:
The control process is segmented into distinct phases: position control for approach and force control for contact. This segmentation allows each control mode to be optimized for its specific function without requiring the entire system to handle both complexities simultaneously, reducing overall control complexity while maintaining reliability.
Solution Approach 2:
The control system uses an intermediary switching mechanism that transitions between position control and force control modes. This intermediary layer manages the complexity by automatically selecting the appropriate control mode based on operational conditions, shielding the user from the underlying control complexity while maintaining reliable contact.
3Measurement precision
If the force sensor is positioned close to the workpiece, then measurement precision is improved, but inertia causes overshoot during contact
Solution Approach 1:
The system performs preliminary positioning to bring the force sensor close to the workpiece for high measurement precision, then switches to force control before contact occurs. This preliminary action allows the system to overcome inertia by reducing speed and preparing the control mode in advance, preventing overshoot during the actual contact moment.
Solution Approach 2:
The system dynamically adjusts the control mode based on the proximity to the workpiece, transitioning from position control to force control as the sensor approaches. This dynamic adaptation allows the system to manage inertia effectively by using force control when the sensor is close and heavy, preventing overshoot while maintaining measurement precision.
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 solution effectively suppresses overshoot and maintains high measurement accuracy and efficiency by reducing inertia and simplifying control arrangements, enabling precise contact and accurate contour measurement.
Implementation Method 1
The vibrating element 4 and the detecting element 5 are formed by one piezoelectric element, the piezoelectric element fixedly bonded on each of front and back surfaces of the base 2
Implementation Method 2
a detecting element 5 that detects a vibration state of the stylus 3 and outputs the vibration state as a detection signal
Implementation Method 3
when the vibration signal Pi having a certain amplitude at a resonance frequency of the stylus 3 is applied to the vibrating element 4, the stylus 3 resonates
Data Source
AI summary
An approach controller (234) of a coordinate measuring instrument enables a position control loop (RP) and drives an actuator (133) so that a force sensor (1) is brought to a close position under a position control. When recognizing that the force sensor (1) reaches the close position, a contact controller (235) controls a switch (227) to enable a force control loop (RF) and drives the actuator (133) to bring the force sensor (1) into contact with a workpiece under a force control.