Servo Controller Help

ajward

Hi All...

I'm using the Prop servo controller to run my biped Wally. It works well (still working on getting him walking), but I have one problem.
When I first power up the servos they =snap= to the center position. The center position is with the 'bot standing up and ready to start walking.
Not a major problem I suppose, but (if possible) I would like to have them move slowly so standing up would be a little more a human getting up off the floor.

If I understand correctly, everything the PSC does is controlled with Spin code. I've looked at the code in the firmware package and I'm not ashamed to admit that stuff is WAY over my head. I'm not afraid to tinker with it (how else can you learn), but I have no clue where to start.

Can anyone point me in the right direction to slow the darn servos down a little?

Thanks for any advice!

Amanda

Publison

ajward wrote: »

Hi All...

I'm using the Prop servo controller to run my biped Wally. It works well (still working on getting him walking), but I have one problem.
When I first power up the servos they =snap= to the center position. The center position is with the 'bot standing up and ready to start walking.
Not a major problem I suppose, but (if possible) I would like to have them move slowly so standing up would be a little more a human getting up off the floor.

If I understand correctly, everything the PSC does is controlled with Spin code. I've looked at the code in the firmware package and I'm not ashamed to admit that stuff is WAY over my head. I'm not afraid to tinker with it (how else can you learn), but I have no clue where to start.

Can anyone point me in the right direction to slow the darn servos down a little?

Thanks for any advice!

Amanda

Hi Amanda,

You could use the “!SCEDD” <1> <CR> command to set a default position at power up.

The default position is set by the “!SCD” <channel> <lowbyte> <highbyte> <CR> command. This is saved in the EEPROM.

The position could be the last servo position command before you power off, (if you know that position.

Another thought would be to invoke the "Servo32_Ramp_v2.spin". I wouldn't know where to put it unless you can share your complete code.

Jim

ratronic

Amanda try loading this into the servo controller. You can change the "RAMP" # in the Con section higher for slower servo movement and lower for faster servo movement. Plug a servo into P1 and play with that "RAMP" #

to get it to move at the speed you want. This sample program just moves the servo from one end to the other at the "RAMP" rate.

Con                                                         
                                                         
  _CLKMODE = XTAL1 + PLL16X                              
  _XINFREQ = 5_000_000
  
  SERVO1 = 1 'P1

  RAMP   = 400
    
Var

Obj

  srv : "servo32v7"

Pub Main

  srv.start
  srv.ramp

  repeat
  
    srv.setramp(SERVO1, 1100, RAMP)  'set servo to begining position

    waitcnt(clkfreq * 2 + cnt)       'wait 2 seconds for servo to move

    srv.setramp(SERVO1, 1900, RAMP)  'set servo to other end 

    waitcnt(clkfreq * 2 + cnt)       'wait 2 seconds for servo to move

ratronic

I have noticed on the startup of the program above the servo quickly rotates clockwise before ramping. I believe that is because the servo has to be set first to know how far to ramp too. I tried the PropBOE Servos.spin object and on it's

first ramping command without setting the position first and it quickly rotates to the middle before ramping. Maybe someone else will chime in on how to slowly move a servo in a unknown position to the starting position that you want?

ajward

@ publison: I'm not sure posting my code would help, but i can. I'm letting the BS2 BOE run through it's program before applying power to the servos, then the servos =jump= to their center position. Same thing if I have a null program loaded to the Stamp.

ajward

@ ratronic: As I understand, a characteristic of the PSC is to set all active servo channels to the center position on PSC powerup, before I've sent any code from the BOE. This has to be done in the PSC firmware (spin code), I think... and this is modify-able... right?

I can always arrange the 'bot to be standing up when I power up the system, I'd like to have him slowly stand up from a pile of "parts on the floor"! :-)

Amanda