Inertia Test Config Attributes

These are the attributes that are associated with inertia test configuration applied to a Motion Control Axis.

Tuning Select

This enumerated attribute is used by the Auto-tuning software to determine where the measured inertia results of the test are to be stored. If set to 'motor test', the measured inertia is stored in the Rotary Motor Inertia attribute or Linear Motor Mass attribute. If set to 'total inertia', the measured inertia is applied to the Total Inertia attribute or Total Mass attribute.

Tuning Direction

This enumerated value determines the direction of the motion profile initiated by the Inertia Test service associated with the Motion Run Axis Tuning (MRAT) instruction.

Tuning Travel Limit

The Tuning Travel Limit attribute is used by the Inertia Test service, associated with the MRAT instruction, to limit the excursion of the axis during the test. If, while performing the Inertia Test motion profile, the drive determines that the axis will not be able to complete the profile before exceeding the Tuning Travel Limit, the drive will terminate the profile and report that the Tuning Travel Limit was exceeded through the Tune Status attribute. This does not mean that the Tuning Travel Limit was actually exceeded, but that had the tuning process gone to completion that the limit would have been exceeded.

Tuning Speed

The Tuning Speed attribute value determines the maximum speed used by the Inertia Test service initiated motion profile. This attribute should be set to the desired maximum operating speed of the motor prior to running the test. The tuning procedure will measure maximum acceleration and deceleration rates based on ramps to and from the Tuning Speed. Thus, the accuracy of the measured acceleration and deceleration capability is reduced by tuning at a speed other than the desired operating speed of the system.

Tuning Torque

The Tuning Torque attribute value determines the maximum torque used by the Inertia Test service initiated motion profile. This attribute will be set to the desired maximum safe torque level prior to running the test. The default value is 100%, which yields the most accurate measure of the acceleration and deceleration capabilities of the system. In some cases a lower tuning torque limit value may be desirable to limit the stress on the mechanics during the tuning procedure. In this case the acceleration and deceleration capabilities of the system are extrapolated based on the ratio of the tuning torque to the maximum torque output of the system. Note that the extrapolation error increases as the Tuning Torque value decreases.

Load Ratio

The Load Ratio attribute's value represents the ratio of the load inertia or mass to the motor inertia or mass.

The value for Load Ratio may be known by the user or may be measured as part of a software initiated Autotune process.

When Use Load Ratio bit is set in the Gain Tuning Configuration Bits attribute, configuration software uses the value of Load Ratio to compute Total Inertia/Mass and System Inertia attributes.

The Load Ratio value may also be used in calculations associated with System Damping attribute.

Total Inertia

Total Inertia represents the combined inertia of the rotary motor and load in engineering units.

Total Mass

Total Mass represents the combined mass of the linear motor and load in engineering units.

Total DC Bus Capacitance

Total DC Bus Capacitance attribute represents the combined capacitance of the regenerative converter and external DC Bus capacitance.

External DC Bus Capacitance

External DC Bus Capacitance represents the combined capacitance of all the external devices that share the DC Bus output of the regenerative converter.