Coordinate Measuring Machine Active Damping for Vibration Control
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Solution Overview
Problem
Coordinate measuring machines (CMMs) face challenges in accurately measuring objects due to dynamic errors caused by vibrations, oscillations, and deformations, which are not effectively addressed by existing methods that primarily focus on static error compensation and simple speed-dependent calibration.
Innovation Solution
A method using a dynamic state model and state-space controller to manage natural frequencies and reject environmental disturbances by actively damping vibrations and oscillations, with a Kalman filter and observers to estimate and control the machine's state variables, ensuring precise movement and measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the frame structure is made of stone (granite) to achieve high static stiffness and good damping properties, then measurement precision is improved, but the machine weight increases significantly requiring high forces for acceleration
Solution Approach 1:
The patent changes the material parameter from traditional granite to carbon fiber reinforced plastic (CFRP), which has fundamentally different mechanical properties - lower density but high specific stiffness. This material substitution resolves the contradiction by achieving adequate stiffness with significantly reduced weight, enabling faster acceleration while maintaining measurement capability
Solution Approach 2:
The patent employs composite materials (carbon fiber reinforced plastic) instead of homogeneous stone materials. The CFRP combines carbon fibers for stiffness and strength with polymer matrix for damping and weight reduction, creating a material that simultaneously addresses the conflicting requirements of precision and accelerability
2Stability of the object's composition
If the frame structure is made heavy with stone to achieve high static stiffness, then structural stability is improved, but dynamic errors from vibrations and resonances during movement increase
Solution Approach 1:
The patent applies dynamic modeling and control techniques to compensate for vibrations and resonances that occur during axis movement. By creating a dynamic model of the machine structure and using active compensation algorithms, the system maintains measurement precision despite dynamic disturbances, resolving the contradiction between structural stability and dynamic performance
Solution Approach 2:
The patent replaces passive mechanical stiffness (relying on heavy stone structure) with active dynamic compensation using sensors and control algorithms. This substitution allows the lighter CFRP structure to achieve the same level of measurement precision through electronic and computational means rather than purely mechanical mass
3Measurement precision
If conventional static error compensation methods are used, then static measurement accuracy is improved, but dynamic errors from accelerations and vibrations are not effectively addressed
Solution Approach 1:
The patent transitions from static to dynamic error compensation by implementing a dynamic model that accounts for accelerations, vibrations, and resonances during movement. The model predictive control calculates optimal compensation forces based on predicted dynamic behavior, effectively addressing dynamic measurement errors that static methods cannot handle
Solution Approach 2:
The patent uses model predictive control to calculate compensation forces in advance based on the planned trajectory and predicted dynamic response. By pre-calculating the necessary compensation before movement occurs, the system proactively counteracts dynamic errors rather than reacting to them after they affect measurements
4Measurement precision
If input-shaping or model predictive control is used to suppress deflections and vibrations, then dynamic measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical damping structures with a computational approach using dynamic modeling and model predictive control. By using software-based compensation algorithms rather than additional mechanical dampers or actuators, the system achieves dynamic precision while keeping the physical device complexity manageable
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 approach significantly reduces measurement uncertainties and errors by actively managing vibrations and oscillations, improving the accuracy and precision of CMMs, especially in high-frequency regions relevant for measurement accuracy.
Implementation Method 1
The dynamic model may be based on a Kalman filter and/or implemented using respective observers
Implementation Method 2
A model-based state controller (31) for controlling the driving unit, the model-based state controller (31) comprising a set of at least one controlling state variable which depends on the actual state
Implementation Method 3
filtering the controlling signal concerning a known frequency response (oscillation behaviour) related to a physical property of at least one of the structural components by use of a frequency-filter element
Data Source
Figure 1~2
Figure 3~4a
Figure 4b~6
AI summary
Method for provide avoiding of excitations of oscillations of a measuring machine (1,2) and/or for reducing or damping such oscillations by actively controlling a driving unit of the measuring machine (1,2) or actively controlling an actuation of an additionally attached actuator. The method using information about an actual state of the measuring device (1,2), the actual state is derived based on a dynamic model and/or by use of a suitable sensor unit. A state controller, an actuator or a frequency-filtering element are used for counteracting or preventing oscillations.