We are considering having distance sensors at front of robot, for positioning when deploying hatches and cargo.
We haven’t done this before - does anybody have recommendations and/or warnings about different sensor types and models - IR, Lidar, acoustic…?
I’ve played around with ultrasonic and IR distance sensors and they both work fairly well. I’m not sure what kind of IR sensor your team has but the ones we have in stock are all digital and only register TRUE at the set distance or closer. we tried to use these in 2017 steam works but all the polycarbonate panels on the field would mess with the sensors and they would often trigger late, or not at all. I haven’t used Lidar distance sensors before but since they’re also optical based I would be careful and test them off of polycarbonate or some opaque materiel covered in polycarbonate just like on the field. As for ultrasonic sensors, those would be my choice of sensor because they’re cheep, teams often have several of them lying around the shop, and they’re not effected by the polycarbonate like optical solutions. However there was a team that had great success last year with Lidar distance sensing and there was no shortage of polycarbonate on the field, and Lidar is supposed to be much more accurate than ultrasonic, so I definitely wouldn’t write Lidar off.
Thank you. We have no sensors at the moment. We see accuracy (down to an inch or less) being pretty important.
Skip ultrasonic unless you go high end; inexpensive IR and light based sensors are better for the close-in stuff.
Also, consider using the camera as a range finder. Since most of the places you’re going will have a pair of vision targets, you can just convert the optical size/separation in pixels to range in inches. You don’t need any deep math to do this empirically - take a few measurements and interpolate between them.
I would advise not going ultrasonic at all, we had too many problems in 2017 with ultrasonic’s. and you could probably just use the wall as a distance sensor. your bumpers should still let you get flat against the wall.
Proper design allows ultrasonics to function fine.
You already have a wonderful MaxBotix sensor in your KoP, and it returns an analog voltage to tell you distance in inches. There are digital outputs as well, but simple analog is easy to play with: Try It, all you need is a voltmeter and power source.
Be sure to read the design considerations on the MaxBotix site when integrating the sensor into your robot, to avoid ‘problems’ from improper design.
Thanks to all for the comments. Off to do some research…
Our team will be using the Limelight to calculate how far we are from our target.
This proximity sensor works pretty well, and is much less erratic than the other sonar sensors we’ve tried in the past. Plus it’s free for the next 374 teams who put it on their FC priority lists.