Creep fall
The creep case is a possibility in a physical system that is in principle capable of vibrations , that it assumes its equilibrium position due to damping in a monotonic ( aperiodic ) temporal course . The alternative to the creep case is the oscillation case . As a mathematical special case, there is an aperiodic borderline case in between for a single damping value .
When a spring oscillator is brought out of its equilibrium position, its mass piece generally moves back to its starting position, but swings over this position, reverses and so on. If this arrangement is in water instead of air, the mass is braked much more strongly. If its movement becomes so slow that it now reaches its equilibrium position without changing direction, this process is called creeping.
Applications
- A swing door that closes by spring force is in principle a system that can oscillate, but is always dampened in such a way that it closes without overshooting, i.e. crawling.
- In control engineering, a sudden change in the reference variable is generally followed by the controlled variable with overshoots . But if z. If, for example, when controlling the temperature of a chemical reaction, the temperature overshoot leads to the destruction of the product, the control device must be designed for a creeping setting.
dynamics
A quick adjustment to a new rest position after a sudden change is often desirable. This can be reached in the vicinity of the aperiodic limit case.
For example, with electromechanical measuring devices, according to DIN EN 60051-1, a lower damping is recommended because the end of the movement process is easier to recognize with an overshoot than with crawling, and because in the case of creep, a measurement deviation occurs more easily due to static friction .
Applications in which the setting free from overshoots is absolutely necessary must be designed for slow changes.