MC-SDK position mode follow

[MWiel.1]

Hi,

I want to control a motor in position mode but also want to be able to just move the motor with no given end position.

I have the positioning mode working so far and recently I found out that when calling MC_ProgramPositionCommandMotor1 with a duration of 0 the TC_FollowCommand function call is used. But somehow I can't get it to work. I'M using MC-SDK 6.2.1 on a STM32F746 controller.

Do have to add something to the code to get this working properly?

[GMA]

Hello @MWiel.1,

What do you mean by "I can't get it to work"? From my side, it seems to follow trajectory using following code:

 MC_StartMotor1();
 HAL_Delay(3000); //Wait for alignment phase
 MC_ProgramPositionCommandMotor1(-0.5,0);
 HAL_Delay(1000);
 MC_ProgramPositionCommandMotor1(0,0);
 HAL_Delay(1000);
 MC_ProgramPositionCommandMotor1(0.5,0);
 HAL_Delay(1000);
 MC_ProgramPositionCommandMotor1(0,0);
 HAL_Delay(1000);
 MC_StopMotor1();

[MWiel.1]

Maybe I'm also misunderstanding what follow mode is capable of.

What I want to achieve is a continous motion in one direction. I either drive to a certain position in a given time or I drive continously at a maximum speed as long as I keep a button pressed.

Below is a sequence I experimented with (MC_StartMotor1() and MC_StopMotor() are handled seperately)

MC_ProgramPositionCommandMotor1(0, 0);
osDelay(0.5 * 1000);
MC_ProgramPositionCommandMotor1(20, 0);
osDelay(0.5 * 1000);
MC_ProgramPositionCommandMotor1(40, 0);
osDelay(0.5 * 1000);
MC_ProgramPositionCommandMotor1(60, 0);
osDelay(0.5 * 1000);

And if I double the values of the target position I hoped for higher RPM which I didn't get.

[GMA]

Hello @MWiel.1,

You can also use the "Trajectory control mode" is a loop with small duration for a smooth rotation

while(push button == true)
{
MC_ProgramPositionCommandMotor1(0.5*i, 0.1);
HAL_Delay(100);
i++;
}

[MWiel.1]

I had thought about it and scrapped the idea because using MC_ProgramPositionCommandMotor1() always has to finish before the next function call to it is accepted. That means the motor drives to the position with acceleration, drive with constant speed and deceleration.

I just tested your solution anyway and it was not a smooth rotation but it was choppy because of the continous stop&go and changing the 2nd parameter from 0.1 to 0.2 but keeping the delay at 100ms didn't help either.

[GMA]

You will have the same behavior acceleration/stop with duration equal to zero...
You have to manage the best position steps and duration for your usecase.