Sweep Scanning LiDAR

[Sperkowsky]

We were doing a demo at Google last week and mentioned more intelligent vision. We ran through a number of ideas until we decided to do some work with lidar. One of guys did work with self driving cars said having two Lidars moving up and down like windshield wipers would be necessary in order to obtain a usable refresh rate.

[cadandcookies]

GOFIRST ordered a couple to experiment with on our VEX U and Ri3D robots. Looked like a great product from a great group of people-- we look forward to having them in hand!

[team-4480]

Looking on their Kickstarter, I see that Team 2473 used it. I am curious on what exactly they used it for. To me, this sensor seems great for obstacle avoidance in an unknown area, but I am not sure what it could do for you in a small defined area.

If you had one for your Stronghold robot, what would you use it for exactly?

[Ari423]

Originally Posted by team-4480

Looking on their Kickstarter, I see that Team 2473 used it. I am curious on what exactly they used it for. To me, this sensor seems great for obstacle avoidance in an unknown area, but I am not sure what it could do for you in a small defined area.

If you had one for your Stronghold robot, what would you use it for exactly?

Obviously I have never used this, so I can only speculate. I see this as an alternative to a camera with easier data for a computer to process. I could imagine it being used to find and center on the batter sections for auto-targeting shots. Could be a viable alternative to vision processing that can't be fooled by changing lighting conditions. It would also give a more accurate distance "prediction" that doesn't require being lined up square with the target (I'm sure some teams have algorithms that don't require that, but the basic one does). I'm not necessarily saying it's worth the cost or the development time, but it has applications.

[scanse]

Tyson from Scanse here: @Ari423 - LiDAR has a couple big advantages over using cameras when trying determine where the robot is in a space. For one, it has a 360 degree field of view. Of course the robot will block some of this, but being able to see most of the field all at once allows you keep track of landmarks while the robot moves and turns. Other advantages are immunity to lighting conditions and less processing overhead. We are still waiting on test data from teams with regard to how well our sensor works in the first environment with clear poly-carbonate and mirror finish diamond plating walls. Both surfaces can be hard to see clearly with LiDAR. Teams will likely want to use other landmarks in the arena for determining the robot's location.

[baumgartensam]

This year we have a XV11 lidar unit on our robot.

One of the largest issues with doing any sort of localization on the FRC field is the polycarb walls. At least in our experience, it is completely invisible to most LIDAR units. Unfortunately polycarb is very transparent to waves in the visible spectrum. Our unit was in the high 700um range which put it out of the visible spectrum, but still low enough to go right through the polycarb. We didn't observe many issues with the diamond plating as long as we did some simple filtering to get rid of rediculous values. The tower works well as a defining feature making common localization algorithms such as AMCL work quite well.

Unfortunetally, we ran into some issues with the housings holding our LIDAR units interfering with the rough terrain so we had to move them to new places which don't have as broad of a viewing angle making localization difficult.

We are however still using one of the units to identify and align with boulders on the field which helps when there isn't a clear line of sight with a ball we are trying to grab. The LIDAR data is much more useful for identifying balls and transforming the balls location into a usable coordinate frame than cameras and CV.

[Mechvet]

Originally Posted by baumgartensam

This year we have a XV11 lidar unit on our robot.

One of the largest issues with doing any sort of localization on the FRC field is the polycarb walls. At least in our experience, it is completely invisible to most LIDAR units. Unfortunately polycarb is very transparent to waves in the visible spectrum. Our unit was in the high 700um range which put it out of the visible spectrum, but still low enough to go right through the polycarb. We didn't observe many issues with the diamond plating as long as we did some simple filtering to get rid of rediculous values. The tower works well as a defining feature making common localization algorithms such as AMCL work quite well.

Unfortunetally, we ran into some issues with the housings holding our LIDAR units interfering with the rough terrain so we had to move them to new places which don't have as broad of a viewing angle making localization difficult.

We are however still using one of the units to identify and align with boulders on the field which helps when there isn't a clear line of sight with a ball we are trying to grab. The LIDAR data is much more useful for identifying balls and transforming the balls location into a usable coordinate frame than cameras and CV.

Appreciate the feedback on these units. If this season's test cases go well, we'll be looking into getting a unit or two for the students to start learning a bit of localization with more real-world tools.

[Pault]

There is a 1.5in angle aluminum at the base of the polycarb walls. Just sayin'.