ActivityBot Servo (or Encoder?) Problem

crazykobnoi

OK. Here's the story.
I just bought a set of ActivityBot and set it all up.
The only problem that I found is the Left wheel doesn't turn correctly.
It always turn backwards in a same speed.
I tried change my code into negative number or different speed. Doesn't effect the wheel.
Any suggestion or solution?

Courtney Jacobs

Hello crazykobnoi,

First, make sure you completed the calibration and got an interpolation table that resembles the one on the bottom of this page. If it looks strange, try comparing it to the troubleshooting page to see if you can locate your problem there. When calibrating, be sure to wait until both P26 and P27 lights turn off after the calibration procedure before powering off the ActivityBot. It can take up to 15 seconds for the lights to turn off.

If you try the above recommendations and your robot continues to behave strangely, run the following program and manually center your servos gently by using a small screwdriver (through the hole in the back of the servo motor). Do not forget to re-run the calibration program once you have manually centered servos.

/*
  Servo Centering.c
*/
#include "simpletools.h"                      
#include "servo.h"

int main()                                    // Main function
{
  servo_set(12, 1500);
  servo_set(13, 1500);
}  

If this doesn't work please call or email technical support (support@parallax.com, 888-997-8267) for additional assistance.

crazykobnoi

Courtney Jacobs wrote: »

Hello crazykobnoi,

First, make sure you completed the calibration and got an interpolation table that resembles the one on the bottom of this page. If it looks strange, try comparing it to the troubleshooting page to see if you can locate your problem there. When calibrating, be sure to wait until both P26 and P27 lights turn off after the calibration procedure before powering off the ActivityBot. It can take up to 15 seconds for the lights to turn off.

If you try the above recommendations and your robot continues to behave strangely, run the following program and manually center your servos gently by using a small screwdriver (through the hole in the back of the servo motor). Do not forget to re-run the calibration program once you have manually centered servos.

/*
  Servo Centering.c
*/
#include "simpletools.h"                      
#include "servo.h"

int main()                                    // Main function
{
  servo_set(12, 1500);
  servo_set(13, 1500);
}  

If this doesn't work please call or email technical support (support@parallax.com, 888-997-8267) for additional assistance.

The servo centering doesn't work. And also I found out that my friends which bought the robot (10 of them) also have these problem, the servo doesn't go in the right speed, right direction, etc.

Courtney Jacobs

Sorry to hear that my suggestion did not solve your issue.

Please contact technical support for more in-depth assistance. It would be helpful to include any code you are running, and pictures of your robot's board connections (servos, encoders, resistors @ P14/15), and wheel/servo positions, if possible.

Mr. Lewis

I would suggest unhooking all wires and make sure all of your wires are plugged in correctly. I have had a few students that hook it up and everything looks right, but they hook it up according to BOE-Bot instead of Activity Bot connections. Also, if you cross your wires (left/right) you could get issues similar to this, be especially careful for both encoders and servos, one student had them switched.

Generally, I've found that if the interpolation data is incorrect, then there is usually a connection issue.

Hopefully this helps.

Tim

crazykobnoi

How do I check which one is L or R? I bought another two sets for servo and encoder parts, and it gt mixed up.

Publison

They can only install one way:

http://learn.parallax.com/activitybot/step-7-mount-right-encoder

http://learn.parallax.com/activitybot/step-8-mount-left-encoder

crazykobnoi

Publison wrote: »

They can only install one way:

http://learn.parallax.com/activitybot/step-7-mount-right-encoder

http://learn.parallax.com/activitybot/step-8-mount-left-encoder

I mean how do I know which one is L which one is R??

Publison

I was incorrect with my previous answer. The brackets and encoders are the same. It all depends how you mount the encoders to the brackets. As long as the connector points towards the back of the robot, (ball end).

http://learn.parallax.com/activitybot/step-1-prepare-your-encoders

Courtney Jacobs

The encoders themselves are not specific to left or right.

How you install them must conform to the mechanical assembly outlined in the ActivityBot section of Learn, but both encoders work on either side. It is how they are mounted to the bracket and then to the chassis that is unique to left or right.

If you are going to ask the forums for help, please include pictures of your setup or you will only receive vague answers and guesses instead of informed responses.

crazykobnoi

Thank you, Publison and Courtney Jacobs :-D