Ultrasonic rangers for obstacle avoidance

[pogenwurst]

For our team's hybrid mode, I've been thinking of using data from four ultrasonic rangers, one on each side of the robot, in conjuction with known distances accross the field, to detect obstacles.

I have to questions about this:

- First of all, is this a valid concept? I can explain in more detail, if necessary.
- Secondly, what beam width should we look for for optimal performance? Maxbotix's LV-EZx (which seem to have worked well for several teams) sensors come in configurations of 4 different beam widths -- from my research, it would seem that the LV-EZ4, with the longest beam width, would be most effective, but I would like to be sure before we buy any.

[Stuart]

aahh young padawon( I say this cause this is what Ive been doing for the last week day in day out hour in hour out). yes it is a valid concept.

the things you will want to look at are . . finding the right shape of sensor set up vs your drive chain. little hint unless your a crab drive think stop sign not street sign. as far as what sensors to use and beam width . . well think of the shape of your chassis vs the blind spots each beam will have. you also may want to think about mixing brands of sensors . . will some places on your bot not need much coverage while others not so much? . . that sort of thing.


and as to not take away any of the fun your about to have Ill leave any more hints and tips to PMs if you want/need some help.

[David Brinza]

As far as I know they are legal this year. I also know that the Bomb Squad (Team 16) used them last year and they could sense the "spider feet" with them in automode. We're considering using them for more than one function...

[kaszeta]

Originally Posted by pogenwurst

For our team's hybrid mode, I've been thinking of using data from four ultrasonic rangers, one on each side of the robot, in conjuction with known distances accross the field, to detect obstacles.

I have to questions about this:

- First of all, is this a valid concept? I can explain in more detail, if necessary.

Team95 has used these and infrared ranging sensors in the past, with mixed results. They generally work (although IR works pretty well for bot avoidance, it's bad if the stuff you're looking for is polished diamond plate), but there are a lot of little gotchas (like ultrasonic sensors getting false readings from loud noises like pneumatic valves). Testing is the order of the day.

[Mib]

We're thinking about mounting 2 of them at the corners of our bot, so we can sense the wall. Maybe just run around the track as one of our hybrid modes (1ish laps), and turning based on objects intersecting. We're also mulling over the possibilities of one mounted on the head to detect objects strait in front of us (other robots, walls, etc).

But realistically, I don't think it's feasible to safely navigated near the opponents during the hybrid mode. Also, as a saftey feature, we're considering one button be designated towards 2-5 second slowdown..pause...speedup phase so we can avoid hitting other robots.

[pogenwurst]

Thanks for the insight guys. I think we'll order one Maxbotix LV-EZ0 (the widest beam width), and then order additional ones if testing goes well.