Robo-Cross
Template:EventLinksBox Robo-Cross is an event in which participants must design and build a robot capable of performing various tasks. This robot must meet certain parameters, such as size, method of control, electricity used, and overall safety.
Event Overview
Participants must build and design a robot that will be able to move objects into goals to receive points.
Playing Field
This year there will be two goals, a small goal and a large goal. The large goal is an empty 10x10x12 cm box on it's side in zone D. The small goal will be an empty 10x10x8 box placed on its side in zone C. Both of the goals will be on the outside corner of their zones. The following materials will be placed in zone B:
- 4 2x4 lego blocks
- 1 tennis ball
- 4 ping pong balls
- 4 AA batteries
Soince.org Example Playing Field
Scoring Points
The maximum amount of points you can score is 183. If your robot is completely in zone B at the end of the competition you will receive 3 points, if it is in zone C you will receive 5 points, and if it is on zone D you will receive 15 points. For every object that is in the jug, and the jug on its side, every object in the jug will receive a 2x multiplier. For every object in the jug, with the jug standing up, it will receive a 3x multiplier. You will also receive points for the following:
| Item | Quantity | Zone C | Zone D |
|---|---|---|---|
| Ping Pong Balls | 4 | 2 | 4 |
| AA batteries | 4 | 3 | 6 |
| 2x4 Lego blocks | 4 | 1 | 2 |
| Tennis Balls | 1 | 4 | 8 |
Getting Started
The Ultimate link- http://www.soinc.org/events/robocross/index.htm
Build a board/playing field.
There are many ways to get started, but the easiest way is with a mechanical construction set or a kit.
- The Vex Kits is a good, but somewhat pricey set to begin with. It will yield decent robots, but expect to pay for marked up proprietary components.
- Lynxmotion is a good place to find parts and well-designed kits for robot chassis. There are also complete sets of construction blocks (based on servo brackets) available.
Some Ways to Pick Up Objects
There are many ways to do this. The following are based on the assumption that your robot will be gathering objects and placing them in container, so that you can gather many objects at once, making minimal depositions to the goal box, and in turn reducing run time. These methods are preferred over strategies that collect the objects piecewise.
Doors
Robots using doors in most cases use either one or two door system. The diagram on the right consists of two doors. Each door is attached to an axle which is also attached to motor. As the motors turn, the doors, or rather flat sheets of material, perhaps aluminum or card-stock, open and close. The operator would open the doors, drive the robot forward and close the doors, while hitting the objects into the container. The operator then moves on and gathers all other required objects on the field using the same method. A one door system would have the same motor, axle, and door setup.
Sweepers
The sweeper system consists of a motor attached to a long axle. The axle is parallel to the ground, and has "flaps" attached to it in places along its circumference. These "flaps" act the same way as the doors in that they hit the objects on the field into the container which is being used to collect the objects. A potential problem with this design is that the flaps can hit the objects with so much force, that if the object is light enough, it can go flying out of bounds.
Arm and Claw
A claw could also work. A good strategy would be to get a claw that picked the object up and then reached back to put it into a container. You could fill it up as much as possible and then transport it into the goal, or use it to pick up objects and put them in the goal. With an arm attached to the claw, it could improve accessibility and distance. This would solve the problem of the vehicle moving closer to the object to reach it, and instead bumping the object and making it roll farther and farther away. To see ways to build an arm, see the Robot Arm page.
Servos and Radios
Servos
Robots are usually powered by special motors called servos. Servos are special motors equipped with a gear mechanism set, and a potentiometer, a device that measures resistance. Servos are widely used by hobbyists and in robotics because of their relative ease to use, and one very special quality: The ability to hold its position. A normal motor spins continuously because it has no potentiometer, and no gears, and can be easy to stop, and can not hold their position; They just spin and spin. A servo, on the other hand, will hold its position when there is no action, and if any pressure is applied to the motor, something that is trying to move the servo horn or shaft, it will compensate by increasing pressure in the opposite direction. Two very important things to know about servos: One, they have to have a signal. Servos can not simply be powered by a simple battery, one wire in the negative, one in the positive. They must be powered by a signal, carried by the signal wire. A servo has three wires, two for power, and one for signal, a very special voltage pulse. Two, servos can only rotate 90 degrees. A signal pulse, unless modified by a speed controller, can only turn the servo 90 degrees (for most radios), and 180 for micro-controllers, etc.
Radios
Radios are a set of two devices, one receiver, and one transmitter. They are used to control servos and motors. The receiver is well, the receiving part of the signal. This is connected to the device in question, and all the servos and motors are connected to the receiver. The receiver receives a signal from the transmitter, the remote in the user's hand that sends signals to control motors from the receiver. Radio Systems are found in usually 1 to 6+ channels, getting more expensive by each extra channel. The most popular, and now standard in Radio Systems are 2.4 Ghz Spread Signal Systems. These are very popular because its link can not be broken, and is nearly nearly impossible for there to be interference from other systems, even if they are the same brand. Note that the transmitter and the receiver must be part of the same brand to work. A receiver and transmitter of different brands will NOT work. Each channel on a receiver controls one servo or component, unless there is a Y-Harness connecting two servos to one channel. Even so, the signal will be identical with each motor, and will move identically. Note that for normal motors, not servos, to be used with a 2.4 Ghz receiver such as a car motor, the motor must be a brushless motor and not brush motors. You can find servos and radio systems and brushless motors at all R/C shops or websites.
See below for other radio frequency systems.
Tournament Student Self Check List
Before turning in your robot for impound, please check the following qualification parameters for your robot. Robots that do not meet these parameters may compete but will be ranked after those robots that do. Additionally, if a RC robot is operating on a band other then 27, 49, or 75 Mhz it is not in compliance with FCC regulations and may not compete in the Robo Cross event. Also, check to make sure that all parts (arms, claws, etc.) are inside the 30x30x30 cube beforehand. It may be easy for one of these parts to move and go outside of the cube if your robot has that capability.
-No more than one robot may be used by a competing team. (Rule: 1-a)
-Control system must be powered by a battery, which is not to exceed 9.6 volts. (Rule: 1-c)
-Robot must fit into a 30cm cube prior to the start of competition. (Rule: 1-d)
-Robot is powered by commercial batteries. (Rule: 1-e)(Its really the only way to determine your voltage, and homemade batteries are just too dangerous)
-Batteries do not exceed 9.6 volts. (Rule: 1-e)
-Voltage output on robot does not exceed 9.6 volts. (Rule: 1-f)
-Only electric circuits � no hydraulics, pneumatics, or fluidics. (Rule: 1-h)
-If a transmitter is used, it is to be powered by a commercial battery with an output not to exceed 9.6 volts. (Rule: 1-i) (That mean no laptops or 8 AA 1.5v batteries, one alternative can be 8 1.2 rechargeable AA batteries)
-Robots must have a legible I.D. with letters 1� tall or larger. (Rule: 1-j)
- RC models are in approved frequency range � 75Mhz, 49Mhz, or 27Mhz. (Rule: 1-k) (It's actually illegal for land vehicles to operate at any other frequencies. Do not buy Aircraft transmitters; however, some manufactures sell the same transmitters for Land use.)
Bring to competition:
- A copy of the rules
- Any clarifications from soinc.org, in case the judges aren't aware of the clarifications. This is especially important at invitationals, when judges are less likely to have read all the clarifications.
- Duct tape
- Scissors and/or knife (box cutters, etc)
- Soldering iron and solder, because sometimes the judges will let you repair wiring on the spot (but they are not supposed to)
Links
- Servo Reference:http://www.princeton.edu/~mae412/TEXT/NTRAK2002/292-302.pdf
- New York Coaches Conference http://newyorkscioly.org/SOPages/Events/RoboCross.html