DRV8711: Stepper motor jerky motion

Hi Sai,

It may be easier to provide some guidance based on your current settings?

Can you provide your register settings?

What is your sense resistor values?

How are you advancing the motor (STEP input or SPI)?

What is your starting speed?

How much does the speed increase every 10ms?

At 300 RPM, you may be able to start without any acceleration.

Hi sir ,

  BOOST DRV8711 am using 

my Rsense resistor is 0.05 ohm.

am starting speed of my motor is  1 rpm.

Am appling step input to the driver.

am using s curve so there is no fixed speed increment in my system(i will increase 2 rpm approximately).

My motor starting frequency is less than 300rpm so i need acceleration and deceleration.later i will add some load to my system. 

REGISTER DATA

intially  am follwing TI tunning guide only.

SPI_Write(0x11,0x32); //100-µs sample, Torque 50(dec) output current 2.14 amp,ISGAIN 5

SPI_Write(0x20,0x32); //off register Internal indexer, 25 µs off time

SPI_Write(0x30,0x00); //Adaptive blanking, 1-µs current blanking

SPI_Write(0x45,0x10); //decay register,Use auto mixed decay, mixed decay time has no effect

SPI_Write(0x5A,0x02); //STALL REGISTER,BEMF/8, Stall after 2, approximately 20 mV (requires experimentation)

SPI_Write(0x60,0x00); //DRIVE REGISTER,Minimal drive, minimum OCP deglitch and threshold

SPI_Write(0x0C,0x11); //850 ns dead time, gain of 5, internal stall detect, 1/4 step, enable motor.

 NOTE: power supply am using 24V/14.6 amp SMPS.

Hi Sai,

Do you need to start the motor at 1RPM?

Most steppers can start at a much faster speed (60RPM is a typical value). If you do not need to start at 1RPM, please discuss the maximum starting speed with your motor manufacturer. Also, please ask the motor manufacturer to provide the resonant frequency of the motor.

Do you know what frequency range causes the jerks? This should also help narrow down potential tuning suggestions.

If it is possible to run the motor continuously at any speed, please provide the range that jerks.

I did not see any issues with the register settings.

Hi sir,

Thank for valuable information

        I need one rpm because am developing my application for camera surveillance purpose.so as much possible i need to run low rpm as well as high rpm based requirement

exactly i don't know the jerk range(frequency). Presently am programming   32 micro stepping at 70 to 120 rpm (7khz to 12khz) then am getting jerks.may be this is the resonance for my motor.

In some paper suggested increasing the micro stepping will reduce the jerky motion.but in my application it is not happening.

I will contact motor vendor and i will update exact resonance frequency data.

When am accelerating to surtain speed then only am getting jerks.once i reached to constant rpm am getting any jerks........

                                                       Thank you

Hi Sai,

As you found, there are papers that suggest using microstepping to reduce the jerky motion. And other papers suggest accelerating through the range as quickly as possible.

Unless there is a reason to operate in the resonance range, it is recommended to avoid the range.

Also, having no load can increase effect of the resonance. Please connect a load or add a damper. A web search will help explain damper operation.

Please update us when you have the motor manufacturer information.

Hi sir,

     Motor Manufacturer providing 72 to 144 RPM is resonance range of  D57CM31-4A stepper motor.That much of rpm i cant skip in my application.

So am looking for alternative methods to avoid the jerks.am tried with the load also but there is no improvement in my motion.This jerks also am not getting everytime out-of 10 times am getting 3 to 4 times............

                                                                                                                                                                                                                     Thank you

Hi Sai,

Can you provide a list of what you have tried to date and the results?

This list should include register setting changes (decay, torque, microstep, etc.) and step input changes.