Determining stiffness

The configuration of some application types (e.g. tower sway and belly sway) requires the parameters "Spring stiffness between tower and traveling vehicle" and "Damping degree between tower and traveling vehicle" to be defined. If you do not already know these values from, for example, mechanical simulations, they can be determined from the signal curve of the oscillating system.

  1. Activate the "Support for parameter determination" function in the "Basic settings" section of the "Anti-sway control" configuration menu.
  2. Load your application with the required payload and move the lifting axis to the position where the highest oscillation of the tower occurs. For example, for the "Tower sway" application type this is usually the highest point at the tower and for the application type "Belly sway" the center of the tower. If necessary, update the value for the parameter "Distance between lifting and traveling vehicle” If the application does not allow it to move to the recommended position without anti-sway control, the oscillation can also occur at a lower lifting height or with less load. Update the parameters accordingly.
  3. Deactivate the anti-sway control to measure the oscillation by selecting the setting "Anti-sway control OFF" as the "Application type".
  4. Move the application and record the amplitudes of the oscillating system, e.g. by means of a video recording, at the point of greatest oscillation. If there is enough torque back to the motor from the oscillating mass, a scope recording of the torque can also be used.
  5. Use the recordings to determine the 3 parameters illustrated below. The peaks of the oscillation amplitudes can also be specified as a ratio to each other regardless of their amplitude (e.g. 1 : 0.8). The "Oscillation period" can also be determined over several periods (e.g. measured time / number of oscillation periods)

[20]

Oscillation amplitude (1st peak)

[21]

Oscillation amplitude (2nd peak)

[22]

Oscillation period (time between 1st and 2nd oscillation amplitude)

  1. Reactivate the anti-sway control by selecting your application type. Check the setting for "Name of axis for lifting position" if you use the application type "Tower swing".
  2. Enter the determined measured values (see diagram) into the corresponding setting fields in the configuration menu "Anti-sway control".
    • The values "Damping ratio between tower and horizontal drive" and "Spring stiffness between tower and horizontal drive" are calculated and used directly for anti-sway control.
    • The natural frequency, resonant frequency and "Deflection at lifting height" are determined for plausibility checks against reality and design calculations.
  3. Perform a plausibility check using the value "Deflection at lifting height" in the "General information for assessing the design" area in the "Anti-sway control" configuration menu.
  4. Deactivate the "Support for parameter determination" if the parameters "Distance between lifting and traveling vehicle" or "Mass of payload" are used for operating the application.