YASKAWA E-S Series Product Manual

Contents

8.4 Estimating the Moment of Inertia8.4.1 Outline8-88.4 Estimating the Moment of InertiaThis section describes how the moment of inertia is calculated.The moment of inertia ratio that is calculated here is used in other tuning functions.8.4.1 OutlineThe moment of inertia during operation is automatically calculated by the SERVOPACK forround-trip (forward and reverse) operation.The moment of inertia ratio (i.e., the ratio of the load moment of inertia to the motor moment ofinertia) is a basic parameter for adjusting gains. It must be set as accurately as possible.Although the load moment of inertia can be calculated from the weight and structure of themechanisms, doing so is very troublesome and calculating it accurately can be very difficultwith the complex mechanical structures that are used these days. With moment of inertia esti-mation, you can get an accurate load moment of inertia simply by operating the motor in theactual system in forward and reverse a few times.The motor is operated with the following specifications.• Maximum speed: ±1,000 min -1 (can be changed)• Acceleration rate: ±20,000 min -1 /s (can be changed)• Travel distance: ±2.5 rotations max. (can be changed)8.4.2 RestrictionsThe following restrictions apply to estimating the moment of inertia.Systems for which Execution Cannot Be Performed• When the machine system can move only in one direction• When the range of motion is 0.5 rotations or lessSystems for Which Adjustments Cannot Be MadeAccurately• When a suitable range of motion is not possible• When the moment of inertia changes within the set operating range• When the machine has high dynamic friction• When the rigidity of the machine is low and vibration occurs when positioning is performed• When mode switching is usedNote:If you specify moment of inertia estimation, mode switching will be disabled and PI control will be usedwhile the moment of inertia is being calculated. Mode switching will be enabled after moment of inertia esti-mation has been completed.• When feedforward is setSERVOPACK ServomotorMovementspeedReferenceResponseTravel DistanceNote: Execute moment of inertia estimation after jog operation to a position that ensures a suitable range of motion.