Technical terms

Nominal force F₀ [N]

Nominal force that a mover can continuously apply.

Force constant K_F [N/A]

Specification of how much force in N the mover generates with a certain mover current.

The equation is F₀ = I_0Mover x K_F

Voltage constant K_E [Vs/m]

Induced motor EMF related to 1 m/s as a peak sine value on a motor coil.

Thermal time constant tTH [min]

Specification of the heating time of the cold module when loaded with the nominal force until 63% of the maximum overtemperature is reached. This temperature rise happens in a much shorter time when the motor is loaded with the peak current.

Absolute accuracy [mm]

Specification of the difference between an expected set position and the mean value of the actual position resulting from approaching the set position from different directions (multi-directional). The absolute accuracy is valid within a module and is defined as the difference between the set position and the actual position of the positioning system.

Standstill repeatability [mm]

Specification of how accurately the system positions when approaching a position from the same direction (unidirectional). The standstill repeatability is to be evaluated as the average difference between the actual position and the set position and is the most important measure for the assessment of a positioning system. It defines the variance around the mean value with a large number of positionings.
The variance of the positions is illustrated by the Gauss distribution or normal distribution. The standstill repeatability is defined by three standard deviations (3σ) with a probability of 99.74%.

Synchronization accuracy [mm]

Specification of the fluctuations that the system exhibits in the position / following error during a position-controlled movement at a constant set velocity. The synchronization accuracy depends on the mechanical rigidity, the applied load on the movers, the controller settings, the set velocity and also any mechanical offset between the modules.