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alternatives to 3d sensors

asked 2013-09-20 07:18:16 -0500

Massbuilder gravatar image

updated 2013-11-18 07:18:25 -0500

tfoote gravatar image

Is there any way to use a sonar or a sharps Ir sensor in place of a laser scanner or 3d depth sensor like a conenct in the navigation stack? If so please send examples or a very detailed explination.

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answered 2013-09-22 05:46:59 -0500

Yeah. I beleive it is possible and you can run navigation stack with Sharp's IR scanner, although the resolution may not be good as the default methods. See the following links

http://www.showusyoursensors.com/2010/08/ros-and-other-ramblings.html

This is how its done in Pi-Robot

http://www.youtube.com/watch?v=6oDrO5EKU5w

http://www.pirobot.org/blog/0014/

and here is some code

http://code.google.com/p/vanadium-ros-pkg/source/browse/trunk/arbotix/src/arbotix_sensors/lidar.py?spec=svn19&r=19

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Just a note, we pretty much abandoned the PML stuff when the Kinect came out -- it works a lot better with ROS navigation than the slow-updating PML did.

fergs gravatar image fergs  ( 2013-09-23 01:55:33 -0500 )edit

do I have to install openni to use the kinect(or other camera depth sensor) with the naviagtion stack?

Massbuilder gravatar image Massbuilder  ( 2013-09-23 09:50:56 -0500 )edit

yes sure, u need openni, Kinect outputs a pointcloud , then using the package pointcloud_to_laserscan (depthimage_to_laserscan in ROS Hydro), you have to fake it as a laserscanner.

achuwilson gravatar image achuwilson  ( 2013-09-24 02:14:38 -0500 )edit
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Parallax sells a 1d laser rangefinder on their website, maybe the PML can be used with that.

Massbuilder gravatar image Massbuilder  ( 2013-10-02 03:04:13 -0500 )edit
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answered 2014-10-24 20:21:18 -0500

TimboInSpace gravatar image

It's totally possible. I have a little robot that does some basic SLAM, just using two ultrasonic rangefinders. However, I found that gmapping took some heavy tweaking to get to work properly using such noisy & low spatial resolution sensors. The whole project took a couple XBees, some servos, an arduino, the rangefinders, and my laptop.

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would you mind sharing those tweaks in detail

Massbuilder gravatar image Massbuilder  ( 2014-10-27 20:55:42 -0500 )edit

Now I said it's possible, but the disclaimer is that it will never be as good as a laser. The main gmapping tweaks: - Set resolution to match sensors. For my SRF-04s, I used 4cm - Increase particle count, to account for relatively low sample rate. - Buffer the ultrasonic, publish as sets of points!!

TimboInSpace gravatar image TimboInSpace  ( 2014-11-02 13:46:38 -0500 )edit
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answered 2013-09-24 03:29:08 -0500

Hendrik Wiese gravatar image

You definitely can. We are using Sharp's IR sensors to generate a point cloud which is then given to the navigation/tf stack.

Here's the code of our IR sensor interface: http://pastebin.com/9EK7W8Dm

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I've changed the frame the points were published in due to this misbehavior: http://answers.ros.org/question/82351/no-obstacles-detected-in-particular-region-on-the-map/

Hendrik Wiese gravatar image Hendrik Wiese  ( 2013-09-24 04:54:27 -0500 )edit

thanks this will be rally useful but I have some questions about the code, first your code references a #include "otter4_eth_interface/CAN.h" which also the msg type received by ir interface class. I am guessing it is specific to your project so what would be the equivalent msg for me to use

Massbuilder gravatar image Massbuilder  ( 2013-09-27 14:00:40 -0500 )edit

Exactly. The CAN message is specific to my robot. That's got to be substituted by your specific message containing your IR data.

Hendrik Wiese gravatar image Hendrik Wiese  ( 2013-09-27 20:58:32 -0500 )edit

The micro controller that will be very likely sending the data uses strings sent via usb, can I use those?

Massbuilder gravatar image Massbuilder  ( 2013-09-28 06:36:22 -0500 )edit

what type of data is in the can msg anyway? I am assuming it is distance data.

Massbuilder gravatar image Massbuilder  ( 2013-09-29 03:57:28 -0500 )edit

I forgot about this one, I'm sorry. The CAN msg is just a container that contains different types of commands and parameters highly specific to our hardware. You can use whatever kind of message you like. You've just got to decode/unpack/parse them. Pretty easy with Python in my book.

Hendrik Wiese gravatar image Hendrik Wiese  ( 2013-10-27 14:52:11 -0500 )edit

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Asked: 2013-09-20 07:18:16 -0500

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Last updated: Oct 24 '14