Definition of Terms Concerning Acceleration, Speed, and Torque

Overview

Motion Sizer calculates the acceleration, the speed, and the torque for different positions in the mechanic.

For acceleration and speed, the following rules apply:

oAcceleration and speed values are always positive, the direction of movement is not indicated.

oAcceleration and speed are applied to the load in rotary (for example, rotary tables) or linear (for example, conveyor belts) direction. This is determined by the load case selected in the Mechanic.

oSince the shaft of a machine is rotating, acceleration and speed applied to the shaft is angular.

If you specify environmental conditions, then derating is applied: The values indicating the characteristics of a device, for example, Max. motor speed are automatically reduced by the derating factor.

If you specify a reserve, this reserve only has influences on the results displayed in the Device Selection dialog box. It can have the effect that new combinations of drive, motor, and gearbox can become valid or that others can become invalid in the Device Selection dialog box, depending on the defined reserve. Nevertheless, the application and the device characteristics themselves are not changed.

Definitions

Term	Explanation
Peak acceleration	The highest acceleration that occurs during the application cycle. This value is shown for information purposes and is not compared to any value by Motion Sizer.
Maximal speed	oMaximal speed required by the application: The highest speed that occurs during the application cycle. oMaximal speed provided by the gearbox: Characteristic of the gearbox. oMaximal speed provided by the motor: Characteristic of the motor¹.
Effective speed	oEffective speed required by the application: The effective speed that occurs during the application cycle. It is the RMS (root mean square) of the speed over time. oEffective speed provided by the gearbox: Characteristic of the gearbox. oEffective speed provided by the motor: Characteristic of the motor¹.
Peak torque	oMaximal torque required by the application: The highest torque that occurs during the application cycle (at any speed). oMaximal torque provided by the gearbox: Characteristic (constant value) of the gearbox. oMaximal torque provided by the motor: Characteristic of the motor¹. It is defined as a function of speed, as shown in the Torque over Speed diagram. For every point in time during the application cycle, the torque of the application at that time must be ≤ the maximal torque at the speed of the application at that time. oA special case is the Quick stop nominal torque provided by the gearbox (which exists only for the gearbox, but not for the motor): It is the maximal torque permissible, for example, for emergency stops. Motion Sizer compares this value to the maximal torque provided by the motor. It verifies whether the motor could brake with a torque. NOTE: This is only a calculated value. You have to perform any necessary considerations for emergency stop scenarios of your machine.
Effective torque	oEffective torque required by the application: The effective torque that occurs during the application cycle. It is the RMS (root mean square) of the speed over time. oEffective torque provided by the gearbox: Characteristic of the gearbox (constant value). oEffective torque provided by the motor: Characteristic of the motor¹. It is defined as a function of speed, as shown in the Torque over Speed diagram. When only a single value is provided, the type of speed is indicated in the parameter name: oEffective torque at nominal speed: The effective torque at the nominal speed of the motor. This value is provided for informational purpose. oEffective torque at effective speed: The effective torque at the effective speed of the application cycle (that is equivalent to the Effective speed required by the application, see description above). The Nominal torque required by the application is compared against this value.
1 Whenever a characteristic of the motor is mentioned in this table, the value in question is actually a characteristic of the selected combination of motor, drive, supply voltage, and PWM frequency (as selected in the Axis editor). It is called motor here to distinguish it from the characteristics of the gearbox.