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Help with Remote Control Robot

I want to make a simple robot which runs by REMOTE CONTROL . It should be able to cross some hurdles such as stones etc. and also should be able to carry or drag ball to specified targets.so please help me to build such robot.

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Thanks for being so considerate.

Actually I want to make simple 4-wheeled car which has some mechnism to carry or drag a table-tennis ball.

I personally don't want it to be much bigger.ideal size would be 25*25*25 or less than that.Also Iwant to build it myself from scratch so thst i can increase my skills.

actually, I don't know much about autonomous operation and hence i decided to build it remote controlled but once i have mastered it i would surely convert it into autonomus.

Also will you suggest me a mechanism on how to descend stairs.

Thank You,

Mayuresh 

I'd say your options for 4 wheeled vehicles are rack and pinion steering or skid steer. With skid steer you drive both wheels on either side at teh same speed and steer by skidding one or other side (strangely enough). With rack and pinion, you need to consider that if you power only one wheel, you'll need to be constantly adjusting the steering to keep it straight. Alternitively you might consider a differential drive allowing both wheels to be powered.

Not to dispute you BoA, but there are many other options that you did not mention.  For example, I have seen an excellent 4 wheel drive, 4 wheel steering 'bot.  And a great fixed axle, center pivot 4 wheel 'bot.

I've not seen a 1 wheel drive, rack and pinion steered 'bot as you described.  I'm not saying that they don't exist.

All I'm saying is that there are MANY options.  ( I have a 4 wheel drive, skid steer 'bot in it's infantcy, on the work bench now. )

I'm still looking for the correct platform for my future 4 wheel drive, 4 wheel steering 'bot.  I think that'd be the cat's pajamas.

 

Duane S

Wilson, North Carolina  USA

Disputing me is bad.

I'm thinking "first robot". 4 motors and 4 servos is probably not what the client is after for a first outing.

1 wheel drive rack'n'pinion is spectacularly common in childrens toys, even ride-on ones.

There are, indeed, many options. Not even taking into account the inventiveness of the individual, but I'd speculate that the LAST thing the junior roboteer wants is the worlds longest list of drive mechanisms. At this stage in the their robotics career, they want someone to make it easy for them and that involves discretely removing part of the decision making process...! (Hope you don't mind, mayuresh, if my guidance is ... well, umm ...  "guided".)

Good points, BoA. 

Duane S

Wilson, North Carolina  USA

I could visualize a 1 wheel drive kart robot, but can't point to one directly. Go-karts can be 1-wheel drive, using parts like this one from Northern Tool. The center of the wheel has some bearing that rest on a stationary shaft, and the engine has a clutch to a sprocket with a change directly to a gear on the wheel as shown.

A 3 wheeled, steered, one wheel drive robot would be the Arobot from Arrick robotics. Front wheel drive, rear wheels steer like a harvester.

Those Northern Tool wheels look suspiciously like my big chaser wheels. Each has a pair of bearings. Rather than having a stonking great cog on the outside, though, I just mounted a steel bar with the motor coaxially.
Yeah, Northern tool has some good stuff, even plans and all the parts to make go-karts. Big Chaser is pretty cool with how you attached the drive to the wheels. I have a large robot in prograss that uses car window motors, similar but lighter than the windshield wiper motors you've got on big chasre. I've kludged together a PVC end cap into a "crown gear" that sticks into the wheels, and then attached to an allen key oing in the end of the motor shaft. A bit questionable, but hopefully it will hold together (with enough epoxy). Mine is intended for the outdoor robot contests that have been of interest lately (Chicago, Dallas, Seattle, San Francisco) though I need to get some more parts attached and get programming worked on.

Aye, car windscreen wiper motors are not ideal. They use a worm gear which is very lossy by nature. This is compensated for by a hight current motor. Consequently, you have a lot of ampage for is disproportionate amount of output power. That said, it IS powerful enough to carry me about at 3 km/h.

If only wheelchair motors wheren't som damned expensive, hard to get and hard to control.

An allen key? Sounds almost like you're building a Constant Velocity (CV) joint? Are you doind powered steering or a suspension or something?

These window motors have a hexagonal hole in the end of the shaft, but no flat or keyway to attach to. There is a square at the base of the output, but I thought the hex key/allen wrench nin the end would be a good way to have a no slip engagement of the motor to the wheel. Just a simple differential drive, no suspension or fancy joints other than the air pressure in the tires.  Oh, these motors also have a worm gear, just aren't quite the size of wiper motors.

 NPC robotics has some of the big expensive power chair motors, thought they are cheaper there than they would be from a medical supply. And some of these occasionally are seen on surplus sites for a bit less. And Ebay.