Random reset

[luckyluke]

Sorry about pwm frequency it is 6219 Hz

I didn't get the "minimum pwm percentage".
Is it minimum percentage which robot start to move?
If so it is %5 with fully charged 3s lipo.

[Ttelmah]

It's the lowest PWM percentage you use.
If you want full torque at this, it's pulse width must be greater than the time it takes for current to climb to it's full value. So for the data from the motor,

5*L/R = 75.6uSec

So with this being 5% of your full pulse width, the highest PWM frequency you can use and have full torque from the motor is:

1/(76.5uS*20) = 661Hz.

So currently your PWM frequency is massively limiting the motor torque (particularly during start-up).....

[luckyluke]

I misunderstood.
I thought it was the first point that motors move the robot.

My minimum is %50 for turning maneuver.

I will setup pwm to 500 Hz.

Have a look at this video, see what is this for:

https://www.youtube.com/watch?v=QZK6KX8qj-A

At 1:19 somebody has a reset problem !!

[Ttelmah]

Seriously, the changes will only reduce it.
You need to actually design your supplies and inter-wiring carefully to avoid it.
It's worth realising that the starting current even with the 2S battery will be 2A momentarily as power is first applied. With the 3S, it'd be right on the 'absolute maximum' rating for the drive electronics....

How is your code setup to stop?. Does it brake the drive or let the motor coast?. Understand if the latter, that there can be exceptionally large voltages.
How about reverse?. Do you bring the motor to a halt before applying reverse?.

[luckyluke]

start up maneuver for example

[Ttelmah]

So when you switch from 'forward', to 'right', what is done to the left motor?. Is it braked or allowed to free run?. If you are going forward, and the motor has reached full speed, how is it ramped down for the turn?. How long do your acceleration and deceleration ramps take?. Given it is on a tiny operation, it suggests that your code may be making a mistake in this operation, perhaps doing something like stopping the motor 'dead' or letting it freewheel and as a result a nasty current spike is resulting, which is what is glitching the supply.....

If a behaviour occurs at a particular transition, then it strongly suggests that something about this transition is causing a problem. That it is the shortest, may suggest that the code does something incorrect when the motor hasn't finished changing speed.

[luckyluke]

I have function motor(left,right);

motor(75,-75)
motor(75,0)
motor(75,75)
motor(75,0)
motor(75,-75)

0 is means set up hbridge forward with zero duty.
If it was forward it will be free run,
if it was reverse it will be brake.

There is no ramp for increasing or decreasing.

[Ttelmah]

If you have no ramp, and no deceleration time, then if you go from a forward to reverse on a motor, it will cause horrible current spikes. Also if you are allowing the motor to free-wheel and you switch from 'forward' to 'right', then the driven motor on the left will tend to push the right hand motor which is already spinning making dynamo generation terrible. Understand that the energy coming from a motor when you do this, will be being fed back into he power rails via the trap diodes. I hate to think what current may be going through these, and what is being fed onto the power rails. You should be looking at ramping the motor speed a little. Otherwise your code is like a driver who insists on stopping their car by driving into a wall....

[luckyluke]

I need sudden movements because of this i didn't consider ramping.
Now i am adding it and will try again.

[luckyluke]

Problem has been solved with the suggestions of Ttelmah.

Changes i made:
Regulator has been replaced to robust model mic29500 with tantalum capacitors.
A 1000uf added to driver supply.
10 nf and tvs diodes added to motors
driver, sensor and microcontroller + - lines separated in the pcb.

[luckyluke]

Just a follow up to this:
Got the unit working, and have done rather well in a recent robot competition with it.