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pogenwurst
07-01-2008, 01:39 PM
I know that a good number of FRC teams have used Maxbotix's excellent little rangfinders.

My team has four EZ0s -- they went unimplemented this season due to time crunch and inexperience, but I've thought up what I believe to be a solid use for them and plan to implement said use for Georgia FIRST's off-season competition.

My question, then, is this: have any teams that have used them come up with a particularly robust way of mounting and protecting them on your robot? Rangers do no good if crushed to bits.

Kingofl337
07-01-2008, 03:48 PM
In 2007 we mounted one in a piece of 1.5" square tube with some plastic spacers and 4-40 screws. We also potted the board with hot glue to protect it from shorts.

EHaskins
07-01-2008, 03:52 PM
I don't know if it counts as robust or well protected, but all I did was use a couple of zip ties to hold it to a piece of polycarbonate. That was a last minute addition, but I didn't have any issues with it.

EDIT: In 2006 I used a generous amount of hot glue to secure it to a servo. I didn't have any problems with that either, but maybe I'm just lucky.;)

Phalanx
07-01-2008, 07:28 PM
Our solution was to use thick double stick tape to leave them exposed, but we also mounted them 6 inches inside the robot from the edge of the bumpers/frame.

We did that because the ranger reports everything 6 inches and closer as 6 inches therefore we would know that at a reading of 6 inches we were right up against what ever the object is.

pogenwurst
07-02-2008, 12:07 PM
Thanks for all your replies.

In 2007 we mounted one in a piece of 1.5" square tube with some plastic spacers and 4-40 screws. We also potted the board with hot glue to protect it from shorts.

You don't happen to have a photo of that, do you?

Tom Line
07-03-2008, 10:05 AM
We got the smallest job-box that fit from radioshack and simply hot glued the sensor to back. Then we used a dremel to cut a circle in the cover of the job box.

The sensors were well protected. Our front one took a hit so hard that the job box broke off it's mountings and the sensor still worked fine, until I melted it trying to resolder a wire that I broke :) .

Also remember to strain relieve your wires so no force is put on the solder connections.

On another note, was anyone who used the maxbotics able to improve their "slow" response and the initial overshoot they see when going from a short distance to a long one?

We wrote software that minimized the maximum amount the sensor could change in one loop to remove the overshoot, but there have to be better options.

In addition, the sensors couldn't respond quickly enough to give accurate readings at 15 feet per second. We had to set our front sensor to stop the robot at 48 inches. By the time the sensor saw 48 inches, our front end was about to contact the other robot.

Jon236
07-06-2008, 02:20 PM
We had similar time-response issues. I hope the cRIO will give us a quicker response!

pogenwurst
07-06-2008, 09:09 PM
Thanks for your response, Tom.

We had similar time-response issues. I hope the cRIO will give us a quicker response!

Maxbotix's rangers update at a maximum rate of 20 Hz, so I don't think the controller change will help much in that area, unfortunately.