Modular, Multi-Platform, 300A ESC

zpc128 said:
Hello mxlemming, I use VESC6MK5 to run MESC, and now I can run the motor with the command set uart_req 3, but opt_cont_type default is Torque, I change it to Speed and send set uart_req 3 The motor is not running, how should I test the Speed mode?
Click to expand...
Sorry, its been a long time since I wrote the speed controller and i rarely use it. From looking at the code, it seems there's another parameter for speed req that needs setting and its not connected to the UART req.

I'm away for a few weeks... You can try adding the speed req parameter to the terminal list in mescinterface.c
 
mxlemming said:
Sorry, its been a long time since I wrote the speed controller and i rarely use it. From looking at the code, it seems there's another parameter for speed req that needs setting and its not connected to the UART req.

I'm away for a few weeks... You can try adding the speed req parameter to the terminal list in mescinterface.c
Click to expand...
Okay, thank you for the answer, I'll read the code first, familiarize myself with the idea, and then see how to change it.
 
zpc128 said:
Okay, thank you for the answer, I'll read the code first, familiarize myself with the idea, and then see how to change it.
Click to expand...
Hi mxlemming

Like zpc128, I am also trying to run in Speed mode and has added this parameter (last one below) in MESCinterface.c

Code: 
desc = TERM_addVar(mtr[0].FOC.Idq_req.q         , -4096.0f     , 4096.0f      , "iqreq"         , "mtr[0].FOC.Idq_req.q"                                                                     , VAR_ACCESS_TR , NULL      , &TERM_varList);
    TERM_setFlag(desc, FLAG_TELEMETRY_ON);

    desc = TERM_addVar(mtr[0].FOC.speed_req           , -4096.0f     , 4096.0f      , "speed_req"         , "speed request"                                                                     , VAR_ACCESS_TR , NULL      , &TERM_varList);
        TERM_setFlag(desc, FLAG_TELEMETRY_ON);

After setting opt_cont_type to 1 (speed mode) and doing this command

set speed_req 20

I get this message
Code: 
sb@MESC>get speed_req
  Parameter             | Value             | Min      | Max      | Description
  speed_req             | 0.000000          | -4096.00 | 4096.00  | speed request

usb@MESC>get opt_cont_type
  Parameter             | Value             | Min      | Max      | Description
  opt_cont_type         | 1                 | 0        | 4        | Cont type: 0=Torque, 1=Speed, 2=Duty, 3=Position, 4=Measuring, 5=Handbrake

usb@MESC>set speed_req 20
  Variable not writable

usb@MESC>

Not sure how to make it writeable at the moment.
 
socjcare said:
Hi mxlemming

Like zpc128, I am also trying to run in Speed mode and has added this parameter (last one below) in MESCinterface.c

Code: 
desc = TERM_addVar(mtr[0].FOC.Idq_req.q         , -4096.0f     , 4096.0f      , "iqreq"         , "mtr[0].FOC.Idq_req.q"                                                                     , VAR_ACCESS_TR , NULL      , &TERM_varList);
    TERM_setFlag(desc, FLAG_TELEMETRY_ON);

    desc = TERM_addVar(mtr[0].FOC.speed_req           , -4096.0f     , 4096.0f      , "speed_req"         , "speed request"                                                                     , VAR_ACCESS_TR , NULL      , &TERM_varList);
        TERM_setFlag(desc, FLAG_TELEMETRY_ON);

After setting opt_cont_type to 1 (speed mode) and doing this command

set speed_req 20

I get this message
Code: 
sb@MESC>get speed_req
  Parameter             | Value             | Min      | Max      | Description
  speed_req             | 0.000000          | -4096.00 | 4096.00  | speed request

usb@MESC>get opt_cont_type
  Parameter             | Value             | Min      | Max      | Description
  opt_cont_type         | 1                 | 0        | 4        | Cont type: 0=Torque, 1=Speed, 2=Duty, 3=Position, 4=Measuring, 5=Handbrake

usb@MESC>set speed_req 20
  Variable not writable

usb@MESC>

Not sure how to make it writeable at the moment.
Click to expand...

Hi zpc128,

I thought I'd share what I found since mxlemming is away for a while and may not be able to answer our questions.

I made some progress in being to spin the motor in speed mode using the Debug feature in CubeIDE. I have set the Control Mode to Speed but somehow I see it back to Torque mode in CubeIDE after starting the debug session..
So anyway, before switching to Speed mode, I set these under FOC. My default speed_kp=0.5 and speed_ki = 0.1.

1743524848379.png

then I switched to Speed mode ( entering 1 opposite ControMode ) and after this, I could spin the motor.
1743524975264.png

by changing speed_req in increasing numbers, I can increase the motor speed. The tricky part is determining speed_kp and speed_ki ( which I haven't figured out what's a good setting). Initially, I get overcurrent errors. I am using a small outrunner motor: 320kv-16s 20A max motor. After some trial and error, I was able to get a sensible value ( I think ) for speed_kp.
 
Last edited:
socjcare said:
Hi zpc128,

I thought I'd share what I found since mxlemming is away for a while and may not be able to answer our questions.

I made some progress in being to spin the motor in speed mode using the Debug feature in CubeIDE. I have set the Control Mode to Speed but somehow I see it back to Torque mode in CubeIDE after starting the debug session..
So anyway, before switching to Speed mode, I set these under FOC. My default speed_kp=0.5 and speed_ki = 0.1.

View attachment 368119

then I switched to Speed mode ( entering 1 opposite ControMode ) and after this, I could spin the motor.
View attachment 368120

by changing speed_req in increasing numbers, I can increase the motor speed. The tricky part is determining speed_kp and speed_ki ( which I haven't figured out what's a good setting). Initially, I get overcurrent errors. I am using a small outrunner motor: 320kv-16s 20A max motor. After some trial and error, I was able to get a sensible value ( I think ) for speed_kp.
Click to expand...

I figured out how to make it work, and be writable via the terminal. I added the 2 parameters speed_kp and speed_request with the RW attribute . I could have added speed_ki but for now in my setup I did not have to change it. So the 2 lines added are

TERM_addVar(mtr[0].FOC.speed_req , -4096.0f , 4096.0f , "speed_req" , "FOC_speed_request" , VAR_ACCESS_RW , NULL , &TERM_varList);

TERM_addVar(mtr[0].FOC.speed_kp , -4096.0f , 4096.0f , "speed_kp" , "Speed proportional gain Kp" , VAR_ACCESS_RW , NULL , &TERM_varList);


After rebuilding, I change the mode to speed mode, entered the speed_kp that worked for my case and then issued the command by setting speed_req to , say 20. I was successful in being able to control the speed via the terminal.
 
Well done on getting this to work. I have no idea how i got it to work without the variables being in the terminal, can only guess that some commit/merge erased them. I'll add them back. Just got to the end of a very exhausting European tour visiting various factories and colleagues and clients...

Regarding kp and ki... The way to determine them i think is to choose a bandwidth w and then
kp=w/J and
ki=kp*J/f

Where J is the rotational inertia and f is the viscous friction coefficient. w should be between 0 and the speed control loop frequency... 100hz by default... You can't go higher than the control loop frequency.

But in practice, mostly you wouldn't know J or f so tuning with ki=0 and increasing kp until it responds quickly without oscillating and then increasing ki until the steady state error is largely eliminated without oscollation is probably easier in most cases.
 
mxlemming said:
Well done on getting this to work. I have no idea how i got it to work without the variables being in the terminal, can only guess that some commit/merge erased them. I'll add them back. Just got to the end of a very exhausting European tour visiting various factories and colleagues and clients...

Regarding kp and ki... The way to determine them i think is to choose a bandwidth w and then
kp=w/J and
ki=kp*J/f

Where J is the rotational inertia and f is the viscous friction coefficient. w should be between 0 and the speed control loop frequency... 100hz by default... You can't go higher than the control loop frequency.

But in practice, mostly you wouldn't know J or f so tuning with ki=0 and increasing kp until it responds quickly without oscillating and then increasing ki until the steady state error is largely eliminated without oscollation is probably easier in most cases.
Click to expand...
Thank you. I appreciate very much that even with your busy schedule at work/home you are able to provide useful information to guide us in learning about this system.

Overall, I was able to spin the motor using speed control but at lower speeds, I see that sometimes the motor stalls. I am using sensorless mode so I suppose that explains it. The tuning part I will deal later. Maybe an improvement at some point would be to try to estimate the inertia and the friction of the motor within the code to get a better handle on KP and Ki.

Currently, I am looking at using Position control with the goal of being to use the MESC/MP2 as a servo controller. I am using an AS5600 encoder using the I2C interface and some guy has used this before althouhg on a different platform ( ghent360 - Overview). I decided to use the libraries since the AS5600 is cheap and with a few 3-d printed parts can be mounted on a motor.

I did look at the .ioc file that came with the project and noticed that UART3 uses the same pins as the I2C2 interface. on the f405 pill. I disabled UART3, ernabled I2C2 and remove references to |huart3 in main.c ( a few lines below)

UART_HandleTypeDef huart3;
DMA_HandleTypeDef hdma_usart3_tx;
.....

After adding the calls to the libraries for the sensor, a few modifications to the code ( motor sensor mode set to Absolute encoder) , and setting FOC.enc_angle= angle from the AS5600 sensor, I am sort of lost as to what other configuration I need to do.


1744901632845.png

specifically on this part
1744901912397.png

I assume that the pos.set_position is the target position but I am confused why it has to be incremented every time the function is called? Where is FOC.PLL_angle set?

Thanks in advance.
 

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The position controller isn't really useful. The hard part of position control is setpoint generation, i never got around to that.

The pll angle is set after the observer or other angle source is run. Its not intended to be modified by the user.

I think you might find i2c is too slow to be used in a high performance position controller. Better to try SPI or best incremental one.

socjcare said:
Thank you. I appreciate very much that even with your busy schedule at work/home you are able to provide useful information to guide us in learning about this system.

Overall, I was able to spin the motor using speed control but at lower speeds, I see that sometimes the motor stalls. I am using sensorless mode so I suppose that explains it. The tuning part I will deal later. Maybe an improvement at some point would be to try to estimate the inertia and the friction of the motor within the code to get a better handle on KP and Ki.

Currently, I am looking at using Position control with the goal of being to use the MESC/MP2 as a servo controller. I am using an AS5600 encoder using the I2C interface and some guy has used this before althouhg on a different platform ( ghent360 - Overview). I decided to use the libraries since the AS5600 is cheap and with a few 3-d printed parts can be mounted on a motor.

I did look at the .ioc file that came with the project and noticed that UART3 uses the same pins as the I2C2 interface. on the f405 pill. I disabled UART3, ernabled I2C2 and remove references to |huart3 in main.c ( a few lines below)

UART_HandleTypeDef huart3;
DMA_HandleTypeDef hdma_usart3_tx;
.....

After adding the calls to the libraries for the sensor, a few modifications to the code ( motor sensor mode set to Absolute encoder) , and setting FOC.enc_angle= angle from the AS5600 sensor, I am sort of lost as to what other configuration I need to do.


View attachment 368862

specifically on this part
View attachment 368864

I assume that the pos.set_position is the target position but I am confused why it has to be incremented every time the function is called? Where is FOC.PLL_angle set?

Thanks in advance.
Click to expand...
 
I see that the tle5012 sensor using SPI has been tried in the past. I will try to get hold of this sensor instead of using an I2C sensor later. You are right that I2c maybe a bit slow but for now I just want to understand position control, if I could somehow make it work, even if it is slow.

I think this is the part in MESfoc.c where PLL_angle is set.

Code: 
ifdef USE_SPI_ENCODER
      tle5012(_motor);
#endif

//RunPLL for all angle options
    _motor->FOC.PLL_angle = _motor->FOC.PLL_angle + (int16_t)_motor->FOC.PLL_int + (int16_t)_motor->FOC.PLL_error;
//We add the proportional error here since we did not add it last iteration
    _motor->FOC.PLL_error = _motor->FOC.PLL_kp * (int16_t)(_motor->FOC.FOCAngle - (_motor->FOC.PLL_angle & 0xFFFF));
    _motor->FOC.PLL_int = _motor->FOC.PLL_int + _motor->FOC.PLL_ki * _motor->FOC.PLL_error;
    _motor->FOC.eHz = _motor->FOC.PLL_int * _motor->FOC.pwm_frequency*0.00001526f;//1/65536

Would you please explain he above code segment is doing?, I see there are the FOC.PLL_kp and FOC.PLL_ki which are the proportional and integral gains in a PI controller but I don't understand this part

motor->FOC.PLL_angle & 0xFFFF));

Why is it being masked with 0xFFFF?
 
socjcare said:
I see that the tle5012 sensor using SPI has been tried in the past. I will try to get hold of this sensor instead of using an I2C sensor later. You are right that I2c maybe a bit slow but for now I just want to understand position control, if I could somehow make it work, even if it is slow.

I think this is the part in MESfoc.c where PLL_angle is set.

Code: 
ifdef USE_SPI_ENCODER
      tle5012(_motor);
#endif

//RunPLL for all angle options
    _motor->FOC.PLL_angle = _motor->FOC.PLL_angle + (int16_t)_motor->FOC.PLL_int + (int16_t)_motor->FOC.PLL_error;
//We add the proportional error here since we did not add it last iteration
    _motor->FOC.PLL_error = _motor->FOC.PLL_kp * (int16_t)(_motor->FOC.FOCAngle - (_motor->FOC.PLL_angle & 0xFFFF));
    _motor->FOC.PLL_int = _motor->FOC.PLL_int + _motor->FOC.PLL_ki * _motor->FOC.PLL_error;
    _motor->FOC.eHz = _motor->FOC.PLL_int * _motor->FOC.pwm_frequency*0.00001526f;//1/65536

Would you please explain he above code segment is doing?, I see there are the FOC.PLL_kp and FOC.PLL_ki which are the proportional and integral gains in a PI controller but I don't understand this part

motor->FOC.PLL_angle & 0xFFFF));

Why is it being masked with 0xFFFF?
Click to expand...
The pll angle is a uint32t and the foc angle is uint16t. This is so that the pll can track a large number of multi turns for position control (65536 revolutions). When the math to get the difference is run you need to discard the extra 16 bits otherwise the result is nonsense.
 
mxlemming said:
The pll angle is a uint32t and the foc angle is uint16t. This is so that the pll can track a large number of multi turns for position control (65536 revolutions). When the math to get the difference is run you need to discard the extra 16 bits otherwise the result is nonsense.
Click to expand...

Got that part. So the missing bit is to keep track of the number of revolutions between PLL_angle and FOCangle and calculate properly the muliturn angular difference, in radians or degrees. I have other questions if you don't mind.

What is the advantage of calculating PLL_angle based on the previous values of PLL_int and PLL_error? Why not use the current values ? And where is the part referring to the last iteration in "We add the proportional error here since we did not add it last iteration". I looked at the code and could not figure this out.

Thanks again.
 
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