Discussion in 'The Projects Forum' started by Team2264, Jul 19, 2011.

1. ### Team2264 Thread Starter New Member

Jul 19, 2011
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0
Hi,

As part of promotion of our FIRST Robotics team at our school, we are trying to build a basketball playing robot. Our goal is to have it play a game of horse against a member of the basketball team.

The idea is to build a consistent shooter, constantly measure the distance to the hoop, and use parametric equations to place the ball in the hoop.

As the first step, we need to be able to track distance to the hoop. Only horizontal distance is needed, as vertical distance is always known. So far we've had a couple ideas:

1) A trackball, like inside an old mouse, that measures distance traveled. It can be calibrated before playing to directly underneath the hoop, and always track its position relative to the "origin."

2) A system with a transmitter/receiver underneath the hoop, and a transmitter/receiver on the robot. The distance between the two halves could then be calculated...somehow.

We are interested in help with the second option. We don't know whether it would use radio waves, optical sensors, sound, or something we haven't thought of.

The system needs to be accurate to within an inch, and have a range of around 50 feet, in order to cover half a basketball court.

Can anybody help? It would be greatly appreciated.

2. ### Sparky49 Well-Known Member

Jul 16, 2011
836
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Perhaps some sort of laser reflected off of an angled mirror under the hoop would do.

The machine would fire a laser, time how long it takes to be reflected back to a sensor, divide the time by two, and using the speed of light, calculate the distance.

It could do this several times a second to make sure it is as accurate as possible.

3. ### John P AAC Fanatic!

Oct 14, 2008
1,727
258
An ultrasonic beeper on (or directly above?) the basketball hoop sends out a "ping" at the same time as an LED flashes. The light arrives at the robot almost instantaneously and the sonic signal is delayed by about 1msec/foot. So you can calculate the distance.

Note that you will have to do some math as the distance from the beeper will be along a diagonal (i.e. neither horizontal nor vertical).