perplexing problem with activity bot

solder_fumes

I had my activity bot (remote control, with track treads) working nicely, then decided to add the Li-on power pack to it. I don't think the power pack is responsible for my issue, but something has changed.

My setup is this...a Propeller activity board on the bot, another Propeller board as the remote controller, and a total of three x-bee's, one one each propeller board, and one as a "traffic monitor"
.
The code is pretty simple, I send a "f", "b", "l" or "r" depending on which way I want it to go, or if no direction button is pressed (i.e., the five position switch is in the center) it send an "s" for "stand still".

When I power everything up, the "s" is continually transmitted (and I can see it on the traffic monitor xbee), and the bot sits there as is should. FIne.
As soon as I hit the forward switch, both servos turn to drive it forward. But after about 4 seconds, the right servo comes to a stop, while the left one keeps spinning.

When I send "b" (for backup), the right servo does nothing, and the left servo continues to drive forwards.In fact, regardless of which direction I toggle the switch (it's the Parallax 5 position switch), the left serve drives forwards. The right servo does nothing.
Occasionally, one servo will stop in mid-rotation and reverse itself.

If I power down the bot and start it again everything sits idle, then as soon as I hit the switch to send it in any direction, the above behavior is repeated.
I'm fairly new to the Propeller and C, so hopefully I've just done something dumb with the code.

Thoughts?

/*
Code for ActivityBot - motors only

*/

#include "simpletools.h"                       // Include libraries
#include "fdserial.h"
#include "abdrive.h"

fdserial *xbee;
int main()                                    // Main function
{
  xbee = fdserial_open( 9, 8, 0, 9600 );      // Begin the serial connection 

  char data;                                  // Create the variable that will be used to hold
                                              // the incoming data
 
  while ( 1 )                                 // Repeat this forever or until loss of power
  {
    data = fdserial_rxChar( xbee );           // Set data to the data received from the XBee board
 
    if ( data == 'f' )                        // If the data incoming is telling the robot to move forward
    {
      drive_speed( 64, 64 );                  // Move forward at 1/2 speed
    }
    
    else if ( data == 'b' )                   // If the data incoming is telling the robot to move backward
    {
      drive_speed( -64, -64 );                // Move backward at 1/2 speed
    }
    
    else if ( data == 'l' )                   // If the data incoming is telling the root to turn left
    {
      drive_speed( -32, 32 );                  // Turn left in a spin turn at 1/2 speed
    }
    
    else if ( data == 'r' )                   // If the data incoming is telling the robot to turn right
    {
      drive_speed( 32, -32 );                  // Turn right in a spin turn at 1/2 speed
    }
    
    else if ( data == 's' )                   // If the data incoming is telling the robot to stop
    {
      drive_speed( 0, 0 );                    // Stop
    }
  }
}

/*
  Five axis joystick control board code
*/
#include "simpletools.h"                            // Include simpletools
#include "fdserial.h"

fdserial *xbee;

int main()                                          // Main function
{
xbee = fdserial_open (29, 28, 0, 9600);

  while(1)                                          // Loop repeats indefinitely
  {
  int button_forward = input(4);                    //assign inputs to direction and functional controls                        
  int button_reverse = input(2);                    //movement controls are wired as active-low pull-up
  int button_right = input(1);                      //firing and gripper controls are wired as active-high
  int button_left = input(3);
  int button_fire = input(8);                       //activates relay
  int button_open = input(7);                       //opens gripper
  int button_close = input(6);                      //closes gripper
  
    
  if (button_forward == 0)                                     
  {
      dprint (xbee, "f" );                          // send "go forward" command to robot, and so on...
      print("forward");                             // prints verification of command to terminal and so on...
      pause(500);
  }  
  else if (button_reverse == 0)
  {   
      dprint (xbee, "b" );                          // backup
      print("back up", CLS);
      pause(500);
  }
  else if (button_right == 0)
  {                    
      dprint (xbee, "r" );                          //turn right
      print("right", CLS);
      pause(500);
  }
  else if (button_left == 0)
  {  
      dprint (xbee, "l" );                          //turn left
      print("left", CLS);
      pause(500);
  }

   else if (button_fire == 1)                      //fires relay
   {
   dprint (xbee, "x");
   print("FIRE!", CLS);
   pause(500); 
 }
 
   else if (button_open == 1)                      //open gripper
   {
      dprint (xbee, "o");
      print("open", CLS);
      pause(500);
   }
     
   else if (button_close == 1)                    //close gripper
   {
      dprint (xbee, "c");
      print("close", CLS);
      pause(500);
   }
   
   else if ( button_forward == 1, button_reverse == 1, button_right == 1, button_left == 1 )
  {
      dprint (xbee, "s");                           //stand still
      print("stand still", CLS);
      pause(500);
  }
  }
}

NWCCTV

Have you reverted back to the way it worked before? I know this may seem a bit off the wall but bear with me. I had a REALLY strange issue with a Wii remote when using Ni-Zn batteries. My wife and I play Tiger Woods golf on occasion. Everything worked just fine. Then, when I put the Ni-Zn batteries in the remote, the "B" button, which is used for the back swing worked, but the game would not respond to the motion. I put the standard rechargeable batteries that I had been using back in and all worked fine. In short, I figured it had to be because the two types of batteries are running on different frequencies and therefore causing issues. This is why I ask if you have tried reverting back yet.

solder_fumes

Thanks Andy for the suggestion. Just gave it a try...along with using a quality bench power supply, the Parallax battery pack, and anything else I could come up that didn't put more than 9 volts on the board. No luck.

I did find that if I leave things powered long enough, eventually one of the servos will come to a slow slow halt (that is, gradually slowing down then stopping...and this is with the bench power supply that is providing constant voltage). If I wait long enough, it will start up on its own. This without sending any directional input to it at all.

Thanks,

John

ValeT

solder_fumes wrote: »

Thanks Andy for the suggestion. Just gave it a try...along with using a quality bench power supply, the Parallax battery pack, and anything else I could come up that didn't put more than 9 volts on the board. No luck.

I did find that if I leave things powered long enough, eventually one of the servos will come to a slow slow halt (that is, gradually slowing down then stopping...and this is with the bench power supply that is providing constant voltage). If I wait long enough, it will start up on its own. This without sending any directional input to it at all.

Thanks,

John

Weird.....Have you tried viewing what is being sent by your transmitting board continuously on the terminal? That will tell you whether the problem is the bot or your code.

Also if the problem is your bot, do you have other/another board/boards that you can use to test with?

Finally, do you have any other servos that you can use to test the connections to make sure it is not a problem with the servos? Have you calibrated your servos correctly?

Good luck,
ValeT