View Full Version : 8 mile-Motor Specification

01-10-2009, 10:31 AM
I think everyone is aware of 8-mile event to be held in IIT Kgp.So can anyone please suggest the best motor specification to be used in this event.

The bot will carry a laptop of weight around 2kgs and other weights include motors and battery.

Also suggest me which type of batteries to be used.Sealed Lead-Acid rechargeable battery would be quite heavy and it would increase the weight of the bot, any other choice except this ?

01-13-2009, 09:22 PM
Guys please help me..

01-14-2009, 09:01 AM
What is the usual current rating of a 12V High Torque DC motor ...in and around how much ???

In that case can L293D be used safely ??Or any other IC ??

Please reply asap.

01-14-2009, 08:21 PM
The choice of motor depends on a number of factors.
1. The maximum speed of robot and hence maximum rpm of motor with load.
2. The actual weight the robot with pay load
3. Number of motors on the robot. ( The total load will get divided between motors)
4. The diameter of the wheel.
5. Points 2,3 and 4 determine the torque of motor required to run the bot. And this is not the stall torque of motor. Typically it would be 1/3rd or 1/2 of stall torque.

Typically high torque motor with decent rpm will draw current around 1-2A
You might want to consider L298 or H bridge with higher current handling capability

Choice of battery depends on total power requirement, how long u want to run the bot before changing battery. Since u r carrying laptop and robot is going to be somewhat heavy it doesn't hurt to go with SLA battery as they are cheap and come with good Ah rating. If u have a deep pocket u can explore other type of batteries, like Lithium ion or NIMh, as well.

01-15-2009, 12:32 AM
Total weight of the robot would be around 8-10 kgs including motors,batteries and laptop.

I would be using 2-12V driving motor with wheel diameter of 70 mm(it can b reduced to 40 mm) and 2 castor wheels.So in that case each motor would take 4-5 kgs of weight.Any easy mathematical formula to get a rough idea of the torque each motor would need ??

Two 12V 10kg-cm torque would do my work to carry a total weight of 8-10Kgs ??

01-15-2009, 05:16 PM
If budget is no limit , Go get a electric scoooter , Its fast , powerful and everything is already there. Will cost around 25k i think .

It'll beat anything else easily.

01-15-2009, 11:10 PM
ohh tats a nice joke... :D

01-16-2009, 04:07 AM
Why a joke ? learn from the big guys.... they used real Cars to traverse the darpa challege .... did not go looking for motors ;) , though this competition is no where on the same scale but when u want to win there is no such thing is over kill :).

An electric scooter has everything in it ( motors , gearing , batteries , chargers , speed controllers etc ) , other than a guidance system ... you just RIP it apart and re assemble to make a Bot.

Only problem is most college kids dont have these kind of budgets ....

06-03-2012, 08:43 PM
I think everyone is aware of 8-mile event to be held in IIT Kgp

No, I dont think so, at least I am not aware of it, it will be helpful if you can post a link to the event, or problem statement.
By reading all the posts in the thread, i assume you need to build something which will travel 8 miles, which will carry a laptop and some payload.It will be of more help if you explain the technical specifications - like the payload, the size restrictions, the speed required, etc.

From my understanding of the problem statement, you should go for a BLDC, which is very much what Vikas suggested. But if not buy an entire scooter, you can get the spares from an electric scooter service center. I remember purchasing the motor of 3.5K and speed controller for 2K in 2008. THe prices might have changed, but it could be indicative.

For something which has to endure 8 miles, the mathematics really come into picture. Make sure you decide on the wheel diameter and the weight of the machine with proper mathematics and not by assumption (like most of the people who compete do) or you will end up with a discharged battery and a blown up speed controller or other parts within 2 miles of the run.

i remember societyofrobots [dot] com has good literature on this for beginners, do have a look.

06-04-2012, 12:22 PM
Looks like an old post dug up and i guess the op is no longer interested in it :p

06-04-2012, 04:14 PM
Looks like an old post dug up and i guess the op is no longer interested in it :p

oh oh... yes.
of all the things, i thought it was a new thread, so didnt bother to check the OP date.

Blame it on the Gin !! :D