What is the Influence on Scanning Caused by CMM Dynamic Performance

1. Dynamic performance impairment

The dynamic performance of CMM restricts the precision of high-speed scanning and interferes with high-speed scanning.
The scanning measurement is different from the trigger measurement, the measuring machine will bear the inertial load during the whole process, and the dynamic performance is more important than the static performance. Inertial load causes deformation of measuring machine structure, which is difficult to predict.
The traditional scanning system satisfies the scanning accuracy by reducing the scanning speed, which is a compromise of dynamic performance barriers.

2. Dynamic error

Scanning will produce inertial force, if the inertia force is not corrected, it will cause measurement errors.
In the measurement of discrete points, the image of the inertial force is not obvious, but in the scanning, the effect of acceleration and the resulting inertial load is obvious. As the speed increases, so does the acceleration. In fact, acceleration increases faster, and in a typical scan trajectory curve, the rate of change in acceleration is the square of the rate of change in velocity.

At low speed, the effect of inertia force is negligible. The traditional scanning system does not have any kind of dynamic compensation and can only work in the low-speed area. If the speed increases, it will become the main factor affecting the measurement performance. Most coordinate measuring machines are used in production environments, and measuring time is very important. If the measurement can be done more quickly, the advantage is very clear.

3. Factors affecting dynamic error

The dynamic error of a significant feature is its unpredictability. There are many factors affecting the dynamic performance of the machine, and it is unrealistic to find an advanced measurement method that can take all these factors into account, and it is limited in most environments. These influencing factors are sorted as follows:

 1) Response speed of the control system: The slower the response speed of the control system, the greater the dynamic error. A fast-response system can correct errors more

quickly, thus reducing dynamic errors.

  2) Stability of the control system: An unstable control system may produce oscillations, resulting in increased dynamic errors.

  3) External disturbance: External disturbance will affect the performance of the system and lead to the generation of dynamic errors.

  4) Design of control system: The design parameters of the control system, such as control gain, integration time constant, etc., will directly affect the dynamic performance and

dynamic error of the system.

  5) Nonlinear characteristics of the control system: Nonlinear characteristics will cause changes in the dynamic behavior of the system, thereby affecting the size of the dynamic

error.

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