Alright. This is the last element for my robot to final come together. I need some help with DC motor control for my robot which will interface with the basic stamp 2.
Here are some requirements:
- Able to go in 2 directions (DUH!)
- speed variations
- simple and easy to make
- easilt programmable with basic stamp 2.
thanks in advance
What kind of motors?
What kind of motors? There are a couple of driver circuits floating around here using the L293 or L298 motor controller.
The L293/298 ICs make
The L293/298 ICs make bidirectional motor control easy, and if you can’t find those try the SN754410, which is the same thing pin-for-pin as the L293 but with higher current output. They’re all very easy to install, drive 2 motors each, require only 2 pins per motor for forward/reverse/brake or 3 pins per motor for forward/reverse/brake/free-wheel. You can use PWM to strobe either the control lines or the enable lines for speed control.
motor for sumo robot
i will only need a motor for a mini sumo robot. i heard that you could make h bridges with transsitors and something about mosfet. anyway to do it with a normal transistor? about the chip. do u have a link to a tutorial with interfacing it with the basic stamp 2?
You can make an H-bridge
You can make an H-bridge with a minimum of 4 BJTs or 4 MOSFETs, but either way it’s unlikely to be as small as an IC version if you want decent current output, which you normally do for a sumo bot. Note that the L293 and similar have 2 H-bridges so you’d need at least 8 discrete transistors to make even a basic replacement.
Depends on the power supply
Depends on the power supply and the motors you will use. The LMD18200 needs 12V minimum supply voltage and can drive up to 3A (with cooling).
Yes, it may work, but the
Yes, it may work, but the h-bridge should be determined by the specs of the motor it is to be used on, not start with an h-bridge and then hope the motor can be run with it.
Post which motor(s) you have or would like to use, then an h-bridge can be found for them.
this is the motor i want to
this is the motor i want to work with. link:http: //www.solarbotics.com/products/gm22/specs/. this is like the last element for my robot (mini-sumo) i think that the high torque and reasonable rpm makes it a good motor for my mini sumo.
So the LMD18200 has been
So the LMD18200 has been disqualified. I would suggest the TB6612FNG Dual Motor Driver carrier from Pololu. A modern MOSFET driver with high efficency and interal flyback diodes.
http://www.pololu.com/catalog/product/713
You can use with 4 AA or AAA Batterys/Accus
The L298 for me would be 2nd choice. It’s an old style driver with BJT transistors. This means you need higher voltage to get the same motor power compared to a MOSFET driver. 6 AA or AAA cells are recommended. External flyback diodes where needed.
The L293D can be used as 3rd choice. Better use 2 of them, one for each motor. Same old transistor technique as the L298. 6 AA or AAA cells. No exterrn flyback diodes needed (internal flyback diodes only for the L293D)
You might consider having
You might consider having the GM20 too, as sometimes speed can be helpful in minisumo, both are the same size.
Another Pololu product to look at
They also have my favorite (right now) motor controller the Qik 2s9v1 that uses the TB6612FGN but adds a TTL serial interface. The programming is just a matter of sending a few bytes over a serial connection. I’ve used it with motors powered by 3xAA’s and 6xAA’s.
http://www.pololu.com/catalog/product/1110
i will
i will consider http://www.pololu.com/catalog/product/713 but im not sure about the connections. about the gm2o, wouldnt the torque be too low???
I don’t know what wheels you
I don’t know what wheels you are planning for your minisumo, but these appear to fit a 3 mm shaft, like on the GM20 and GM22 motors. http://www.solarbotics.com/products/rw2i/ They are 1-1/4" diameter.
The GM20 are 37.7 oz-in at stall, capable of 240 rpm; the GM22 are at 47.7 oz-in and up to 79 rpm.
A minisumo is required to weigh no more than 500 grams or 17.6 ounces.
If using perfectly grippy tires on an opponent minisumo in which all the weight translated to a horizontal resisting force to push, the max resisting force to being pushed would be, well, 17.6 ounces.
The wheels are 1-1/4" in diameter, so motor torque would operate on a lever arm of half that, the radius of 5/8" or 0.625". So taking the weaker GM220 motor torque of 37.7 oz-in and express it on a 0.625 arm comes out to be 60 ounces of push. And that is just one wheel, the other wheel contributes to give a total of 120 ounces of push, more than enough to overcome the 17.6 ounces of weight pushing back. Now this is a vast over simplification that overlooks your own minisumo weight only allowing the 17.6 ounces back, and that there are no perfectly sticky tires to convert all weight into a resisting horizontal force, etc. But what I hope you’ll see is that the motors are more than sufficient to push another minisumo. If magnets or vacuum were allowed that might be another matter.
What comes into play more often in minisumo is momentum and speed. Hitting the opponent with some speed can help carry them off the ring. Even more important is actually staying on the ring yourself. Then probably being able to find the opponent.
thanks for the info! helped
thanks for the info! helped alot . i decided to get the gm20 motor but about the wheels i wanted to mould some wheels http://www.davehylands.com/Robotics/Marauder/Making-Tires/index.html that cover more surface area say 3 cm? the diameter would be about 2.5cm. what do you think of it? im not very good with this engineering stuff 
The molded wheels could be
The molded wheels could be good, more “grippy”. I painted one set of wheels on a robot using silicon sealant as the wheels slowly rotated. Another set I molded, like Dave H did in your link, but mine were molded onto a wheel with some thickness like car tires. The last set of tires I bought pre molded, for a set of wheels I already had.
i am having problems with
i am having problems with making a wheel that is 3cm diametre (with the mold which is about 2.5mm) snd 3cm length made of a pvc tube. i am not sure of how to attach it to the motor as the motor is only 35mm
also, do you know website
also, do you know website that shows a detailed process for me to follow as i am not very good at this kinda stuff.
Wheels can be attached to a
Wheels can be attached to a motor shaft with a friction fit or with a hole drilled in the side and a set screw holding it in place.
I really recommend buying a wheel that fits the 3 mm shaft rather than trying to make a wheel. Getting a straight hole for the motor shaft as well as the set screw can be difficult, espcuially without a drill press and good bits. Making a urethane tire for the wheel can still be done.
