Mechanical load identification
For servo systems, mechanical loads are the controlled objects and important components of the system; Mechanical load identification includes parts such as load inertia, friction force, and load mechanical resonance point. Servo can automatically identify key mechanical characteristics, set control loop parameters and compensation parameters reasonably, and achieve dynamic response performance that meets application requirements, greatly reducing the tuning pressure of on-site debugging personnel.
Usually, we do not pay much attention to the absolute value of mechanical load inertia, but rather focus more on the relative size of load inertia and motor inertia, so it usually appears in the form of "inertia ratio" in the control loop.
Load inertia ratio' refers to:
Load inertia ratio is a key parameter in the servo system, and the proper setting can help to reduce the debugging time.
The servo drive has a built-in load inertia identification function, which can automatically identify the load inertia by this algorithm.
Inertia identification automatic recognition method:
By the buttons on the servo drive panel, make the motor move, so as to realize inertia identification without the intervention of upper computer;
Under the following conditions, it migt be impossible to perform mechanical load identification normally. In this case, please adjust the gain manually.
| Factors of mechanical load identification | |
| Load inertia | Inertia mismatch, load inertia ratio greater than 100 timesLoad inertia is unstable, time-varying or slowly changing |
| Mechanical properties | Extremely low mechanical rigidity, for example, in belt transmission mechanism where the belt is not tensioned.Nonlinear factors such as excessive tooth clearance in operation or excessive backlash in positive/negative rotation, e.g., misaligned gear installation in gear transmission mechanism |
| Movement conditions | Movement speed less than 150rpmWhen the torque for acceleration/deceleration is less than the offset load torque or less than the viscous friction torqueWhen the acceleration is less than 3,000rpm/s |
"Response Level Setting" and re-identify the inertia.
If vibration occurs in the identification process, the inertia identification should be stopped immediately and P1A group - "Response Level Setting" should be reduced.
Before conducting offline inertia identification, first confirm the following:
There is a movable stroke of more than 1 turn in each direction between the mechanical limit switches:
Before identifying offline inertia, please ensure that limit switches are installed on the machinery to prevent overtravel and accidents in the inertia identification process!
If the actual load inertia ratio is large, estimated to be over 30 times greater than the motor inertia, inertia mismatch phenomenon may occur, that results in slow motor operation. In this case, the following 2 measures can be taken:
Preset load inertia ratio of a large initial value, and it's recommended to use the 5.00 times as the starting value, gradually increases until the identification is updated accordingly; The load inertia ratio can be set of '2006-0Bh' by object word, or of "P06.10" through the panel, or of "P06 group load inertia ratio" parameter on the background software
It can be set by appropriately increasing the driver "P1A Advanced Adjustment - Response Level Setting" on the background software, or be set by object word "201A-02h".
The general process for identifying panel operation inertia is as follows:
Inertia identification adopts the form of forward/backward triangular wave motion, and the program has already deErrored to the optimal motion parameters; Users can adjust the motion parameter settings according to actual application scenarios to realize the on-site demands. The identification program motion curve and parameter settings are as follows.
| 0x201A - Advanced Adjustment | ||||
| Subindex | 0x07- Max. speed estimated by inertia | 0x08- Accelerating time estimated by inertia | 0x09- Waiting time estimated by inertia | 0x0A- Rotation turns estimated by inertia |
| Data type | UINT16 | |||
| Accessibility | Readable/writable | Readable/writable | Readable/writable | Read-only |
| Unit | rpm | ms | ms | turn |
| Default | 100 | 125 | 800 | 1.00 |
| Min. | 100 | 20 | 50 | 0 |
| Max. | 1000 | 800 | 10000 | 655.35 |
| Setenable mode | Stop setting/immediate enable | Stop setting/immediate enable | Stop setting/immediate enable | -- |
| Related mode | PST | |||
| Note | Settings of the parameters related to offline inertia identification have been the internal deError optimal values. Generally, there is no need to set them | |||