fidget?

[Remus1814]

Hi, my problem is basically programming and mechanical. our wheelbase is quite small and when our omni wheels start the bot tends to jerk back far and try to tip over. It doesn't but we'd like more traction with the front wheels. is there a way to stop the tipping back without adding a extending wheel set behind to counteract the problem?

[Alan Anderson]

If you want to address the problem without changing or adding hardware, try limiting the acceleration. Don't let the motor power change too rapidly.

[Kevin Sevcik]

to clarify that last post, you want to slowly change the command you're sending to the motors. So you take advantage of the fact that pwm values can stay the same from one cycle to the next and say something like:

if (pwm01 < pwm01_cmd)
{
pwm01 += ACCEL;
}

The point being you add a little more to the pwm command every time through the loop till it's where you want it. Now, you still have to set up the decresing side, and you need to check for special cases like if your ACCEL value is 5, pwm01= 202 and pwm01_cmd = 205. Then you'd wobble back and forth from 202 to 207 to 202 to....

[Protronie]

I don't know where yous stand weight wise but adding some weight to the front of your bot might just do the trick of keeping it from tilting backwards... that is if the added weight wouldn't put you over the limit.

This is often done in tractor pulling...

Just a thought...

[Remus1814]

ya we added a whole 5lbs to the front and im going to ask our programmer to alter the programming to accept better acceleration ty, more ideas would be welcome in case these solutions dont get what we truely desire

[IndySam]

you can also move your battery to the front if you haven't already.

[Joe Ross]

The following whitepaper talks about how to use the gyro to detect tipping and drive to prevent it.

http://www.chiefdelphi.com/media/papers/1509