wt70707's profile - activity

The zeros will not be in the same place every scan. If the robot doesn't move, the "change" is small. For the lidars, the "better" ones may work "long" and well in some environment rich in features, but can't stay "stable" all the time. I am trying on your advice to incept the data somewhere.

I have 5 LIDARs, and the data comes from the "worst" one. Here "worst" means more zero in distance. Zero distance is invalid date which is forced to zero in the ASCII output format.

I put two column of data in the answer: one is 4hz(240rpm) and one is 5hz(300rpm). The format for each column is: A,{Angle},{Distance in mm},{Signal Strength}. I got it using Arduino tools.

I have two mobile robots, both installed with a lidar. Now I want to get position of one robot relative to the other. I am using mapstitch now, but the precision is really bad. Is it possible to localize one of the robot using the map of the other robot?

The package I use now is hector_slam and scanmatcher. Is it possible to do localization with scan data of one LIDAR in the map built by the other LIDAR?

My platform: omni-wheel robots, Ubunu 14.04, ROS indigo, Neato XV-11 LIDAR.

Best Regards, Tao Wang

We also consider to inspect the data stream, but from the test, the dropping bytes can be anywhere, so I can't just discard "single" data. And for each rotation of 360 degrees, all exist "bad data", so I can't discard the whole 360 points of each rotation also.

Hello Billy, there is tool to set the speed with the Teensyduino controller. I had ever change it to 200rpm, but it makes it worse. Here is the link to the tool: https://www.getsurreal.com/products/x...

I use hector SLAM and Neato xv-11 LIDAR. There is problem that the map will jump when the location jumps even the robot doesn't move. (I have a picture of this but has not enough points to attach). I had played with some of the parameters, and even tried to stop publishing the slam_out_pose message when this pose (the location) change too much, some time it works, but it never works all the way.

The jumping mostly happens when there is warning "SearchDir angle change too large".

The neato Lidar ranges from 0.15m to 6m. I had tested it and it has some invalid data, anyway, I think it should survive with that.

I have no knowledge of SLAM. It seems I am just looking for lucky as I go around the code blindly. Looking forward your help.

Thanks.

Tao Wang

Thanks a lot!

I have a question on TCP and UDP. As I need do close loop control with message published on ROS: the robot will collect LIDAR data and send to laptop through the topic mechanism; the control variable should publish from the laptop to the robot also through the topic mechanism.

1. After some study, it seems I should choose UDP, not TCP_NODELAY and surely not TCP. As the default is TCP, so transport hints should be used [ros::Subscriber sub = nh.subscribe("my_topic", 1, callback, ros::TransportHints().udp())]. My question here is on wiki it says "You cannot currently specify the transport hints on the Publisher side. This will likely be an option in the future", if on the publisher side it is still TCP, how can UDP built at the subscribe side? As I understand, UDP means publisher will publish without care if there is connection, am I right?

2. It also says "The UDP-based transport, which is known as UDPROS and is currently only supported in roscpp, separates message into UDP packets". Does this mean I cannot subscribe using UDP in python program, right?

Package: mapstitch, brank hector_mapstitch.

Here I have a scenario of two robots who have LIDARs that will SLAM to have two maps: robot1/map, robot2/map. I remap "world" to "robot1/map" which is the reference of the other robot, and recap "align" to "robot2/map". I cannot figure out how can I deal with "/map". Anyone can help me out?

My purpose is to run multiple robots in "one common map". It seems I can put the tf of "world"(renewed by "world") to "map" (renewed by "align"), but I cannot get correct "location" of robot2, which the transform should be "ground->robot1/map->robot2/map->robot2/odom->robot2/base_link->robot2/laser". So I wonder if topic "/map" can help.

Thanks, Tao Wang