Robot Arm

Robot Arm is slated as a national event for the 2011-2012 season, replacing Mission Possible, after being run as a Division C trial at the 2011 National Tournament. The event involves the construction of a robotic arm to grab, lift, and deposit specific items in prescribed locations. The Trial rules can be found Here

Base
In order to have a functioning Robot Arm, you'll need a base. This can be made out of any material, as long as it fits within the designated 30cmx30cm box. Something to keep in mind is that the base needs to be heavy enough to prevent the device from tipping over when the arm is moving objects around.

The base can also contain a motor used to spin the arm. One possible design of a base can be seen below:



The Arm
Due to the event being named Robot Arm, one should probably include an arm in their device. The arm should have the ability to reach out up to 40cm (Distance from the base box to the North Goal) but doesn't necessarily have to. They really only need to reach 10-15cm outside of the base box if the operator plans on only utilizing the East and West Goals. In order to utilize the North Goal, you'll need to build with a sturdy enough material to keep the arm from breaking or flexing, while also keeping it lightweight enough for your motors to still be able to handle the load.

Your arm will most likely include a number of joints as not only will it need to lift the objects off the arena and up into boxes, but also it needs to bend up to fit inside the 30x30cm base box. Each joint will probably be controlled by a motor. It's up to you how many joints you use, though 2 on the arm and one on the "hand" should be more than enough if done properly. Keep in mind that the number of motors on your device is a tie breaker.

Motors
If you're new to robotics choosing motors can be one of the most daunting parts of the construction process as you have quite a few choices. One of the best choices for this event are servos. Servos are extremely useful in robotics. The motors are small, have built in control circuitry, and are extremely powerful for thier size. Most teams will obtain these through the VEX robotics company. While VEX has somewhat of a negative reputation with some people, there isn't really much wrong with it. Even the national trial winner in 2011 used a VEX robot.

If you're a more advanced builder you might want to look into stepper motors. A stepper motor is a brushless, electric motor that can divide a full rotation into a large number of steps. The motor's position can be controlled precisely without any feedback mechanism, as long as the motor is carefully sized to the application.

The "Hand"
The "hand" is one of the most important parts of the arm. It must also be the most versatile, as it needs to be able to grip pencils, pvc pipe, and nails in order to be a high scoring device. The rules allow for electromagnets which should prove useful for the ferromagnetic nails, so with that part down, you'll have to design a "hand" that can pick up rounded objects.

Kits
The rules state that teams can utilize kits as long as they modify them in some way. The way that you modify them is completely up to you. Here are a couple common choices for kits.


 * Lynxmotion
 * OWI
 * VEX
 * Edge
 * Lego Mindstorms

Practice/Running the event
This event is about 30% design and 70% practice. You can have an arm that could win nationals, but without practice, the design is worthless. The best way to practice is to put yourself in the situation that you would be at a competition. In order to do this you'll need an arena to practice on, printable layouts can be found here. After practicing for a while, you should develop an efficient plan for the order that you will move the objects and how you will move the objects. A finalized version of this will be part of the documentation that you will need to hand into the event director at the tournament.