PDA

View Full Version : A question about micromouse comp. at techfest



Guest
02-18-2005, 07:59 PM
Hi guys,
Few days back one of my friend who had visited techfest stated the the first prize winner at micromouse solved the maze in only 15secs. I would like to know whether he had used steppers or dc motors and if he had used stepppers how is it possible to obtain the required speed for completion of maze this fast.He told me that the person had made motors to run at 600 rpm. I would be very thankful if anyone could tell me more about this.
-Thanking in advance.

ice
02-19-2005, 10:13 AM
If its at 600RPM,its got to be a DC motor.

It doesnt matter what kind of motors u use once
you got sensor feedback.
I

Vivek
02-19-2005, 10:37 AM
He used stepper motors.
and He worked almost full year to prepare for this contest coz last time his machine had developed some problem.

Guest
02-19-2005, 10:52 AM
Vivek but i dont understand how can one run stepper motor so fast, if nybody knows plz to give info about it.
-thanks guys

ice
02-19-2005, 10:53 AM
Vivek,
But can a stepper achive that high a speed?

surephenomenon
02-20-2005, 05:09 PM
slightly deviating from the topic at hand where is the micromouse competition held(other than iit) and neplace i can get more info about it?cant he have used stepper motors geared for rpm?i mean they are generally high torque arent they?

02-25-2005, 10:24 PM
Hi,

I almost missed these questions, as i only see the forum on a weekend and that too not regular.

there are steppers which run at 1000rpm too.
but I doubt this guys steppers were running at 600rpm.

but i am sure they were steppers.

the steppers in floppy drives can take upto 300rpm approx but with a robots mechanical load that goes down drastically.

i doubt he used floppy steppers too.

I wonder how the number of 600rpm went into circulation.
i hope i get time to find out the details.

for example the exact completion time was 18sec not 15sec.
i hope numbers have not been amplified in communication.

using a gearbox is an option but increase in speed would result in torque reduction. hence the robot has to be lighter.
so for now we can assume he found good quality steppers which have torque high enough to be reduced and yet be useful.

cheers!

Gopal Patel
03-20-2005, 11:37 PM
:D yes its stepper motor, bipolar 10 ohm stepper motor,using chopper driver
{ allegro 3952 } and Atmega16 uC . its completed in 15 second and top speed may sometime cross the 2m/second speed... he use PID control for stepper motor ----- yes its the Open Loop PID control ,the whole timing is preloaded in the uC........It took only one month to complete that uC. and Last time He also win the Micromouse -- Second Prize,but first indian to complete the micromouse. last time he use top-down looking sensor and this time side looking ir sensor.............

Gopal Patel
03-20-2005, 11:40 PM
for example the exact completion time was 18sec not 15sec.
i hope numbers have not been amplified in communication.

no number is not amplified but at the competition it took 18 second but after that just to show again he place it second time then it took 15 second,600 rpm can be calculated as 2m/sec and wheel diameter is 4.5cm......rest you can do....

Vivek
03-21-2005, 09:45 AM
Great!!

this is the first time I have seen anyone use a PID control in a hobby robot in India, esp. yantriki.
(i have not seen past 2 yantrikis).

thats really good work ...coz some people are just good at writing algorithms and software and some are good at making hardware.
but he did both and did it well.

cheers!

asimov_18
03-27-2005, 07:14 PM
hi friends i am also working on micro mouse i have made my dc geared motors with 1:50 reduction ratio. i have "jugar"for optical encodes(relative encoders) to read the motors movement. i will be using pic16f84aor 16f628a . any open advices or guidance. let me know.
asimov_18

Vivek
03-31-2005, 07:30 PM
Hi Asimov_18

What kind of circuit are you using to drive your motors ?

First complete what you are making and planning, and then consider the following suggestion.

if you somehow measure the current flowing through the 2 motors by your MCU, then you can control their speeds such that they remain equal. Hence the tendency of the robot to run into one of the walls would be very less.
This is helpful if you are using a digital type sensor to sense walls.

To sense current of your motors -
If you can afford about 0.5 volt less to your motors, put a very small resistor in series with your motor.

now make an op-amp amplifer with a gain of 10, to amplify the voltage across this resistor, and feed the output to the ADC in the MCU.
the 0-5 volt signal is linear with the current in the motor.
(use the differential op-amp configuration for better results.)
(the series resistor would be 1ohm or less and calculate its wattage and put a high wattage resistor else ...smoke..)
(if you use LM324 kind of op-amp note that its max output voltage would be about 1.5V less than VCC.)

well this is just an extra control loop for both the motors which would make the robot very smooth and straight runner.

cheers!

gopoo
04-14-2005, 06:55 PM
dont go for dc motor,they are hardest to control....and stepper motor are
very easy to control.....if you want speed from above discussion you can understand stepper can give speed up to 2 m/s.... :D believe me,i made three micromouse ,two from dc motor,one from stepper motor,only one is working which is of stepper motor....

asimov_18
04-16-2005, 04:33 PM
hi goopo u said u had made three micro mouses . tell me more about them you know other peoples experiences r great for learning. thanks
also send me ur email addess.
asimov
asimov_18@hotmail.com