Technical Manual for EA350 Analog Pulse Type Servo Driver V101 6.5 Real-time automatic gain adjustment 6.5.1 Overview The driver detects the real-time mechanical load inertia during operation, and automatically adjusts the basic gain value based on the detection results in combination with the set rigidity. There are 3 options, applicable to load of different characteristics 6.5.2 Scope of application Real-time automatic gain adjustment applies to the position control mode and the speed control mode.
6.5.3 Operation methods 1) Servo activation OFF 2) P4-00 is set to 2~4; the factory setting is 1 3) Set P4-01 to a low value 4) Properly set the position deviation counter clearing, command input disable, torque limit and other parameters, allowing the motor to rotate normally without obstacle. 5) The servo activation ON, and drive the machine to operate normally. 6) The driver starts to detect load inertia characteristic. 7) Increase the set value of P4-01 (rigidity) to improve machine responsiveness. 8) Observe the positioning time or vibration status, and change to an appropriate value. 6.5.4 Precautions Real-time automatic gain adjustment may be unavailable in the following conditions.
Please change the load condition, or use the semi- automatic gain adjustment/manual gain adjustment (P4-00=1, 0) ➢ After power-on and initial servo activation ON or increase of the P4-01 rigidity value, and before stable load characteristic is detected, abnormal noise or oscillation may occur; this is normal if stability can be soon achieved. If abnormal noise still persists after repetition of continued oscillation or action for 3 times, the following measures shall be taken: ◆ Reduce the set value of P4-01.
◆ Set P4-00 to 1 or 0 to deactivate real-time automatic adjustment ➢ Upon occurrence of abnormal noise or oscillation, the value of P4-10 (inertia ratio) may become extreme; at this time, please set P4-10 to the automatically calculated inertia ratio. ➢ In results of the automatic gain adjustment, P4-10 is written to EEPROM once every 30 minutes. When power is connected again, this data will be used as the initial value for automatic adjustment. ➢ The gain is updated upon stop. When the motor is still running, even if the value of P4-01 is modified the change will not take effect. ➢ The following functions are inactive upon use of real-time automatic gain adjustment:
◼ Acceleration feedback ◼ Disturbance observer ◼ Speed observer ◼ Torque feedforward ◼ Gain switching ◼ Offline inertia identification 6.6 Offline inertia identification 6.6.1 Overview The load inertia ratio will be directly involved in calculation of speed loop gain, and feedforward functions are preconditioned by a correct load inertia ratio. For this reason, before use of the semi-automatic gain adjustment and manual gain adjustment, if conditions are satisfied, it is strongly recommended to use offline inertia identification to obtain a correct load inertia ratio.
6.6.2 Conditions for valid offline inertia identification ➢ The maximum actual motor speed is 150rpm; ➢ The acceleration upon actual acceleration/deceleration is above 2,000rpm/s; ➢ The load torque ratio is stable without any sharp change; ➢ The load inertia does not exceed 120 times that of the motor rotor; ➢ No extremely low mechanical rigidity or large back clearance of transmission mechanism exists.
67 Settings Real-time automatic adjustment 2 Applicable to scenarios with a slow load inertia change rate (at tens of seconds level) 3 Applicable to scenarios with a moderate load inertia change rate (at seconds level) 4 Applicable to scenarios with a fast load inertia change rate (at millions of milliseconds level) Conditions affecting real-time automatic gain adjustment Load inertia When the total load inertia is less than twice or more than twenty times that of the motor rotor Load When the mechanical rigidity is extremely low. When nonlinear characteristics such as back clearance exists.
Motion model When used at the speed of less than 100rpm and continuously at a low speed When in the steady state with the acceleration/deceleration of less than 2,000rpm/s. When the acceleration / deceleration torque is smaller than the eccentric loading and viscous friction torques. When the speed is above 100rpm, the acceleration/deceleration is above 2,000rmp/s and the duration is no longer than 50ms.