RT-AWD - 2 Weeks till FRC

Imagine, if you will, a tricycle. If that's not possible look to the left. This year's 'Iobotics FIRST Robotics Competition robot will feature a new type of drive train system, with interesting physics built in. It is the Reverse Tricycle - All Wheel Drive system or RT-AWD for short. This system is slightly more risky than that of a normal four wheel skid-steer all wheel drive, but is simpler than a four wheel swerve drive system. It is riskier because its center of mass must remain within the triangle formed by the three wheels at all times, or it will tip over and fail miserably. This means that everything heavy should be kept near the front, or is counter balanced on the other side. It is less complicated than a full swerve drive system because only 1 of the 3 wheels rotate, as opposed to all four or even two of the four. Accompanying the extremely fun center of mass equations is the inclusion of the drive programming equations. The equations use the fact that the back wheel that rotates forms the center of rotation. The two front wheels move in a ratio to the distence to the distance from the center of rotation. Unfortunately the drive system doesn't use any thing like ABS or traction guages that tell when wheels slip using the fact that efficent drive comes from static friction as opposed to dynamic friction. The physics and math required for these drive systems are a little out of our league because they require calculus and differential equations... But thats something to look forward to I guess.

This is just part one of three (maybe three) discribing the three main features of this year's 2009 'Iobotics FRC bot. Thanks for reading...

Mark.

Blue Planet Solution! Same day post, part 2!

Another idea, that requires energy to be transmitted wireless, or through VERY long wires are airborne wind farms. This would use the technology of hot air balloon or helium which would hold the pod at a certain height, while creating drag holding the wind farm in place. The turbines would be turned by the natural jet stream very high up in the sky. It would also leave the land open for things like solar farms, etc and it could be done in any area around the world. The only problem is that the technology for wireless transmitition of energy is not up to par. Also I have no idea what the weather would do to the farms. Rusting would be an issue as it would be inside the clouds and icing can be a problem because of cold temperatures and a moist climate.

Thanks for reading
Mark.

Blue Planet Solution!

In the grand scheme of things saving the world from global warming is about an 11 out of 10. Not just because it makes our sky look nicer, but because it would make the world a better place. My solution is solar power, but not the traditional way. Placing solar panels in space in orbit, so they always face the sun, is a solution to the weather problems such as cloudiness, vog, and fog. To transmit energy is the hitch. Currently the technique used to create wireless power is to transmit high amplitude radio waves to a transceiver, but it can only power small objects such as a PDA charger or a wifi head set. Technology would have to greatly improve in this field to transmit energy. The other problem is that some radio waves are blocked by the earth's atmosphere causing a loss of efficiency. Overall this solution is extremely clean, but costly and inefficient, science would have to improve for this solution to be feasible.
Thanks for reading Mark.

Voltage from a Fan

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So I was playing with my previously mentioned computer fan when it randomly started lighting up. I had placed the two contacts of the positive and negative terminals together and place the xion fan in front of a larger more powerful fan and the LEDs inside began to flicker. The reason is the small solenoid on the inside of the fan with a round bar magnet inside of it. When the magnet began to spin the change in area and theta of the magnet caused the current in the fan to move. By hand I could not light it up because the fan moved too slowly. Even with the fan it only slightly lit up. LEDs dont require much voltage and have very low resistance so the current produced by spinning the fan was very, very minisucle. Unfortunately the light in my room makes it very hard to see but if you look very carefully at the corners of the fan, its slighly glowing (mostly the bottom left corner)

Thanks for reading,
Mark.

First Robotics Competition

So in about a month the first robotics competition will be held down at the volley ball stadium at the University of Hawaii and this is a picture of our team with this year's Iolani robotics FRC robot. The tricky thing about this competition is the surface on the ground. This white material is "regalif" or regular glass shower liner. This combined with a special plastic on the wheels give it a coefficent of static friction of .05 making it very hard to drive. The reason for static friction and not kenetic friction is mostly because a wheel uses static and not kenetic. The point on the wheel doesnt want to slip and so when it slips you move slower and dont speed up as fast as if you started slowly and moved faster. The shooter in the center is actually a baseball-ish pitching machine in the sense that the wheels spin really fast so when the plane of the wheels touch the orbit ball the orbit ball moves at the same speed as the plane of the wheel. This allows a fast efficient shooter and gives backspin allowing the ball to fall into the trailer rather than climbing out as would forward spin.

Its kind of late, but thanks for reading
Mark.

Holonomic Drive

Today I was talking with some of my team members, from the 'Iobotics robotics team, about what we were going to do at the 2009 Vex Worlds competition. The idea of holonomic (omni directional) drive came up which brought up an interesting discussion on how to do it and which motors to use and at what power. I did some calcualations on velocity of the wheels and the direction that the bot would travel and came out with pretty simple equations. But for power versus direction it would be slightly more complicated, to do. Because the motors need to follow a polar equation of direction theta vs percentage of power r. The wheels which are parallel to each other have the same power no matter the direction. They follow this equation with the front being at theta = 90. for the top left and bottom right the equation is R = cos ( theta - 45) and the other two it is R = sin (theta - 45). Yet these are not the exact equations to follow because power in the 1.5 amp motors isnt directly perportional to the speed of the motors. Also we want max speed to be max speed not a slowed speed especially when driving forward. The equation is not acutally correct also, because this represents top speed being the sum of each motor, but it would be good to follow a continuous algorythm rather than a broken one/piece wise as we would do other wise.

Phew, long post of an incomplete train of thought...
Thanks for reading

Mark.

Xeon Fans!

So the other day I was messing around with a few batteries and a light switch, to complete and disconnect the circuit. I used two D batteries in series with one nine volt battery to produce a total voltage of 12 volts. This is the voltage required to tun each fan. The amount of coulombs per second, or amperes is .2A which, drained my battery pretty quickly. It only took about two hours for the fan to completely drain the battery. It is a pretty big resistor because it is running a fan, and four LED lights because it has to look cool as well as perform. Though the fan wasn't very convenient because of the battery size it still worked. The potential energy started at a multiple of 12V and was used up to run the fan. This picture to the left is what it is actually used for. It connects to the heat sync which acts like a radiator and pulls hot air toward it and quickly cools it down.

Sorry about this late post :P, Thanks for reading, Mark.