I'd STRONGLY recommend getting a "Proper" LiPo charger. LiPo battery chemistry is nowhere close to forgiving compared to NiCd or NiMH. Fire/ruined batteries/leaks will appear if you just try to dump current into it.

There is an algorithm for LiPos that ICs are specially made for that balance constant voltage and constant current. Look for a low cost LiPo charger, otherwise you'll be looking for a battery and a charger.

For the wheels, make sure they have excellent traction. If your robot needs to stop, it should do so immediately, not skid to a stop which would put you over the line and DQ you. Work on the path first, then experiment with different tire sizes and type to get the performance you want from it.

375 RPM seems way too speedy. I'll echo Markd77's suggestion of the 150RPM or maybe the 250 RPM for starting out. Your code may not be able to keep up with a robot going 90 miles per hour.

 

These are your options with a 6cm diameter wheel, if I was doing it I would get a set of 75RPM and a set of 150RPM and see which works best.
375RPM 117cm/s
250RPM 78cm/s
150RPM 47cm/s
75RPM 23cm/s
60RPM 19cm/s



Just noticed the battery is a 3 cell pack, which is probably overkill. If your microprocessor and everything else will work with 3.6V then 1 cell would be fine, if you need more then 2 cells should be fine, you might need voltage regulators for some components but the motors are supposed to be OK up to 9V (but will go faster). A fully charged 2 cell pack is about 8V.

 

I'd STRONGLY recommend getting a "Proper" LiPo charger. LiPo battery chemistry is nowhere close to forgiving compared to NiCd or NiMH. Fire/ruined batteries/leaks will appear if you just try to dump current into it.

Just noticed the battery is a 3 cell pack, which is probably overkill. If your microprocessor and everything else will work with 3.6V then 1 cell would be fine, if you need more then 2 cells should be fine, you might need voltage regulators for some components but the motors are supposed to be OK up to 9V (but will go faster). A fully charged 2 cell pack is about 8V.

OK, then what should i do can't i make them in home??
which battery charger is god??
1.), 2.) 3.)

 

I have one by Triton that I guess is most similar to your #1, which is capable of charging any battery chemistry from 1.2 to 19 Volts at 5 amp charge and 5 amp discharge for cycling. I think that might be overkill, and rather pricey.

The last one doesn't balance the cells, the first two do. If you will be running the cells low each time before charging, I'd suggest going with number 2. I'm unsure of what that means for cost, but it has the features I was worried about, such as individual cell monitoring during full pack charge.

The first one also also does cell balancing, but you'll probably need to buy an extra connecting cord for full functionality. That charger has features you may never use. The first one would be a charger to get if you plan to do a lot with various types rechargeable batteries, or have a bunch of NiCd/NiMH batteries to cycle and measure their capacity, etc.

So, I'd say go with #2. The cheapest doesn't seem to have intelligent control, such as the common LiPo charge control ICs that I'm pretty sure are in the mid-range option.

If you have lots of spare cash, splurge on the first one, if you already have a good DMM, soldering station, scope of some sort, signal generator, and other items that make up a workbench. Otherwise I'd suggest the second/middle choice. It will perform far better than your original charging plan, minimal risk of fire.

 

So what so i do for charging my battery i was thinking to use home made battery charger i am using 7812( which is giving 11.30 output) with few capacitor to have pure DC and 800mA current ....?

 

Or should i use LM317 regulator??

 

Here some CAD images please tell any changes to do........

 

So what so i do for charging my battery i was thinking to use home made battery charger i am using 7812( which is giving 11.30 output) with few capacitor to have pure DC and 800mA current ....?

No.

You need to use a proper charger. Lithium polymer batteries, although the best in many ways, have huge variances in internal resistance under charge. You cannot charge a pack of more than one cell with a single voltage. They will not chage evenly and best case, you will destroy your expensive batteries very quickly, Worst case, you will start a fire.

A LM317 will not work either.

Proper chargers (like #2 in your list) charge and monitor each cell individually. There is a reason that there are 4 wires coming to the connector on that battery pack you showed us. It gives the chrager access to all 3 cells so it can manage them properly.

Spend the 1100 rupees and do this properly. I realize that is a lot of money. Another choice might be find one on eBay that will ship to India. This one is under 500 rupees.


Edit: You also need to be carefull not to discharge them too deeply either. Keep them above 2.8 volts per cell. Best thing to do is charge them very often. Unlike NiMH, LiPo cells do not like to be deep cycled at all.

 

Here some CAD images please tell any changes to do........

Why are the drive wheels staggered?

 

Why are the drive wheels staggered?

I forget to tell it was my 1st attempt to any CAD software..

 

these are CSD images.......

 

these are CAD images.......

 

more images...

 

Will this model work fine for a line follower...??

 

An image is worth a million words... but they 're not nearly enough. What circuit did you decide to use?

Please post it along with the code. I 'm really curious about what you did. The build looks robust enough. I hope it's not too big for the arena. Dimensions weren't mentioned, now that I think of it.

 

Dimensions weren't mentioned, now that I think of it.

Hi Geo,

The length is nearby 14cm (140mm) and breath is 12cm ( 120mm)....

OK< the circuit you can see in image is LM339 ( Quat op-amp) ...
with 100K variable resistance act as i Wheatstone bridge to terminal of op-amp....

and uC is quick start board containing propeller chip...( spin code)
and sensors are LDR with green LED's.

 

Ok, thanks for the feedback. I was referring to the arena dimensions. I 'd hate to build a robot and then discover it's too big for the challenge.
I suggest you e-mail the organizing committee asking the exact arena dimensions.

 

OK, i forgot to tell the line was of 3cm and the arena will of 3foot X 8foot....

 

Helo,

For the construction of the robot itself, you could take a look at this site:
http://www.mstracey.btinternet.co.uk/index.htm

Bertus

 

Hi Geo,

The length is nearby 14cm (140mm) and breath is 12cm ( 120mm)....

OK< the circuit you can see in image is LM339 ( Quat op-amp) ...
with 100K variable resistance act as i Wheatstone bridge to terminal of op-amp....

and uC is quick start board containing propeller chip...( spin code)
and sensors are LDR with green LED's.

If you are looking for speed, and haven't purchased the parts yet, using IR LEDs and photo-transistors will give you a much faster response time.

It should be pretty easy to swap the emitters and sensors out if you are using comparators on the same board as the sensors, rather than using ADC routines in the software. Software ADC is very slow compared to having the sensor comparators give digital outputs.