# [FTC]: Programming Autonomous Without Second Beacon

Hello Chief Delphi Forum,

Our team ordered one IR beacon for the competition. We release to calculate the distance between robot and beacon (and thus, the kickstand), we need another IR beacon for triangulation. Are there any other ways we can calculate distance between the robot and the center structure?

Charging Champions

NXT ultrasonic sensor?

You actually don’t need two ir sensors to do this. You can use the signal strength to give you distance. Are you using labview or robot c?

To use triangulation, you need to be in a position where you get signal from both beacons. Since each of them is supposed to be set to 180 degrees mode, facing in exactly opposite directions, I do not see how this is possible.

Using signal strength is not very reliable either - for example, it depends on the battery level of the beacon.

If you just need the distance to the central structure, ultrasonic seems like the easiest choice. If you also need to determine the orientation of the central structure, this can be done using only one beacon. Our strategy is to have the robot circling the structure and stopping when the ir sensor sees the beacon from the right direction

I can give you what I believe our programming team figured out for this problem. Our approach to the problem was to take one sensor but 2 readings. The first reading is from the initial starting position the next reading is taken after you go a known distance. We did this by driving 1 rotation or 1’ for 4" wheels. Then you take a second reading. This would then give you a unique position signature for the 3 positions that you are able to tell what the position of the goal is. From there you can execute 1 of 3 unique codes for the different positions.

One thing to note is our programming team has not worked a lot with this since our strategy changed away from it but the idea should still work.

I have been a programmer before so this code doesn’t seem to hard to write.

My team started to work on a similar code. We use one IR sensor, and one ultrasonic sensor. We take readings from both sensors and compare the results to determine the rotation of the center goal.

Hi There! I’ve been trying to figure out how to do that for a long time, I recently found out that the sun was messing with the IR Sensor since we are next to a window, we have a program that starts in the middle of the parking zone with the left wheel on the foam connector line, with the blinds closed and the left beacon (new style) set at 1200hz 360 and the right beacon (old style) facing directly out from the center piece at assuming 1200hz 180? i have 2 ir sensors and 1 ultrasonic (currently not in use until I get the ir working and I can use it for distance from goal) the problem is that i get Ldir = 5 and Rdir = 5 allmost all the time at each of the three positions, any ideas? If you need the code or any other information just let me know and I’ll post it whenever I have access to our robotics computer with RobotC on it