Last dayyyyyyyyyyyy

(Jin) — Wed, 26 Jul 2006 19:52:47 GMT

Anyways, as we know it, it's the last day. The people who are sure to being things (and better remember) are:
Greg - DDR pads [2], Extreme 2, Memory Card
Abraham - PS2
Me - Extreme, Memory Card

Anyone wanna bring like an XBOX or GCN for Mario Kart DD and/or Halo 2? That'd be good <_<. Post up if you think you can bring something.

*bring

Homework?

(AlanHsiaosHub) — Wed, 26 Jul 2006 18:16:35 GMT

What is our homework for this last class on the Thursday of July?
is it just to make a thing of oral report on the final project?

question

(teafo) — Wed, 19 Jul 2006 23:47:32 GMT

hey, what was the homework for tomorrow? i don't remember anything =[

Stuff for July 13th

(abrahamliao) — Wed, 12 Jul 2006 20:06:18 GMT

Few things first:

Someone in the afternoon section left their RCX...

Markus, you forgot your whole robotics kit! It's in the ATDP office.

Please don't leave these things behind. They're expensive, hard to replace, and I also don't like carrying the extra stuff around.

As far as I know Allen your TA and iTA isn't back yet so I have to post stuff on the forum like this.

Now, onto steering:

The most primitive form of steering is having an axle connected to two wheels of different sizes. This will make your robot constantly turn in one direction. Not very useful, but it shows that when you're turning, your wheels are traveling different distances. More on this later.

Steering systems you typically use:

Differential drive - this is the steering drive you have used on your RCX for a lot of the class. Two motors, each connected to one wheel. You can accomplish steering on this drive by making the wheels spin in either direction, or by stopping one wheel and letting the other go. Advantages for this steering system is the ability to turn in place. Disadvantages, well, it slips a lot, so you would never see this on a car because it would burn rubber all over the place.

Steering drive - this is the one you built that uses the differential (grey thing with three small gears in it) and a steering box, using a rack and pinion. This is the steering system all cars have. Advantages are that it is stable over rough terrain, since the steering is connected to a worm gear, which is asymmetrical.

Rack and pinion: (-O- is a gear [pinion] and the /\/\ is also a gear [rack])
-O-
/\/\/\/\/\/\/\/\/\/\

Why need a differential in this steering system?

Anytime your robot steers and you have one wheel on each side, they will travel different distances. The differential is an ingenious device that allows that to happen. A test question may test you on different distances the wheels will travel in a turn. Like on your worksheet.

To calculate that, basically first take the radius of the turn. That will be used to calculate the circumference of the turn of your inner wheel. Add the radius of the turn to the wheelbase - this is the circumference of the turn of your outer wheel. Compute the circumferences (2*pi*radius) and subtract to find the difference.

Alternative steering systems:

Articulated drive-
____
| |___o
|___| _\_
| |
|___|

This system works like a train, except the center axle (drawn as an "o" on this picture) actually has a motor and turns the robot.

Pivot Drive:
____ ____
|___| |___|
o o o | o
_|_

This thing goes, then stops, then an arm comes out of the bottom, lifts the robot up, turns where it wants to turn, the arm retracts, and the robot continues on it's way.

Synchro drive:

-- -- / /
-- -- / /

Those dashes are supposed to be wheels. Basically, all four wheels turn in the direction they want to go. These wheels also spin. Very hard to design, very complex.

Brake drive:

Similar to the differential drive system, except this one you might actually see on a (stuntman) car. The car turns the same way - by braking one side of the vehicle. This would be done with independently controlled brakes, somehow.

Wheeled drive:

Works by increasing or decreasing the size of the tires. Sorta like the "most primitive steering system", except this one you can actually control. I've personally never seen one of these in action.

Tricycle drive:

Same as steering drive but only one wheel in front.

That's it for steering, if you have any questions just post on the forum.

MOTORS:

The basic purpose of your motor is to turn electric energy into kinetic energy.

When you pass a current through a curled wire, a magnetic field is induced (created). You can find the direction of this field using the RIGHT HAND RULE. Basically, a motor is just one big electromagnet, specifically controlled to do what you want it to do.

North is attracted to south, likes repel and opposites attract.

So a motor sorta looks like this:
__ __
/ / \ \
| | -o- | |
\_ \ /_ /

The two thigns on the sides are electromagnets, and the center thing is what is actually connected to your axle. The center axle is powered too, and when one side of the magnet turns on it is attracted to that side. So it spins that way. When it gets there, a COMMUTATOR switches the currents so that the axle will then be attracted to the other side. Thus, the motor will spin faster and faster.

You can change the direction of your motors two ways:
Reversing the current (in the ROBOLAB software)
Reversing the wire (achieves the same thing)

Your motors can be generators also. If you hook two of them up, spinning one will spin the other. This is the exact opposite of a motor - a generator. It converts kinetic energy into electric energy. Then that electric energy goes into the other motor and gets converted back into kinetic.

Calculations:

Power = Current * Voltage

You will mostly see this notated as P=I*V

Floating your motors just cuts the power, they spin freely to stop.
Braking them actually shorts the motors, forcing them to stop.

When you combine motors in a gearing setup, you increase only POWER, not speed, since motors turn at the same RPM anyways.

Homework for Day 6 (July 6)

(Allen) — Thu, 06 Jul 2006 23:14:10 GMT

Finish reports for the "remote-controlled" robot. These are due AT THE START OF CLASS. It is HOMEWORK, so don't come into clas and do it at the last minute.

Build and program the tank robot, which has a bumper featuring two separate touch sensors. The robot should bump into things and make a turn left or right, based on the situation. A version of this robot is on page 37 of your manual, though original designs are always appreciated (granted that they work).

If you have any questions please RESPOND TO THIS THREAD, as others might have the same question.

-Abraham, posting from Allen's account (sorry!)

Happy 4th

(abrahamliao) — Wed, 05 Jul 2006 11:10:14 GMT

Hope everyone had a happy 4th of July! I know I did:

6 shot Black Cat mortar set
6 shot "Festival Balls"
1 rocket
2 helicopters
ground blooms
firecrackers

Union city was cracking, EVERYONE had fireworks. Good times.

Anyone else blow stuff up?

container program

(magicmasterChris) — Sun, 02 Jul 2006 04:09:16 GMT

can someone write out in wording, an example of the odometer/container program? I need to study it a bit longer to understand what's going on.
Whoever's in my steal the bacon group, I'm going to pick any part to write out the thing. so...too bad.

btw, can someone explain torque?

I'm booooooooored.

(Jin) — Sat, 01 Jul 2006 08:10:01 GMT

I'm bored, people. You guys got anything fun to do? Got Myspace? Add me, kthx.

Homework reminder

(abrahamliao) — Thu, 29 Jun 2006 23:28:18 GMT

Homework for the weekend:

Review for test (!!!)
Finish Steal the Bacon robot report
Build parts on pages 45-47 and 70-73, and combine them into one robot

Favorite TV shows

(abrahamliao) — Thu, 29 Jun 2006 19:48:49 GMT

And I know at least some of you watch TV.

Futurama, Venture Brothers and Family Guy for me. Guess those are all cartoons... Whatever.

Robotics: Discussion