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2016-03-01 13:24:07 -0600 commented answer Hi there, i know the question is dumb but is there anyone out there who can guide me to interface my IMU, encoders with ROS. I can not find any tutorial on it.

Please have a look at the rosserial package and the supporting tutorials.

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2015-02-28 04:58:46 -0600 answered a question ax2550 node

I got it working, but this is more of an adhoc solution. Following is the constructor for AX2550 class, the parameter to be passed is the serial port to which the controller is connected.

AX2550::AX2550 (string port): port_(""), serial_port_(NULL), serial_listener_(1), connected_(false), synced_(false){  this->port_ = port;

I believe somehow the parameter wasnt being set and the default parameter shown below was being used,

std::string port;
n.param("serial_port", port, std::string("/dev/motor_controller"));

So i changed it to the following

std::string port;
n.param("serial_port", port, std::string("/dev/ttyUSB0"));

Now it works. But i will have to change the code and re-make the node everytime i change the port. The source code can be found here .

If anybody could tell me what is going wrong with the node, i'd be deeply grateful. Thank you.

2015-02-26 04:16:09 -0600 commented question ax2550 motor controller calibration for ros node compatibility?

Did you find the solution for this?.. Even iam struggling with the same issue

2015-02-25 13:35:30 -0600 asked a question ax2550 node


I have been trying to run the ax2550_node from the ros ax2550 package found here .

But i get an error which says

AX2550 connecting to port /dev/motor_controller
[ERROR] [1424892454.858165528]: Failed to connect to the AX2550: IO Exception (2): No such file or directory, file /tmp/buildd/ros-hydro-serial-1.1.7-0raring-20141231-2116/src/impl/, line 150.
[ INFO] [1424892454.858316111]: Will try to reconnect to the AX2550 in 5 seconds

I have tried changing the port permissions as suggested by this user ( ) but to no avail. Could anyone please help me resolve this issue.


I have switched the usb-serial converter. I am now using Aten uc232-a. I am able to communicate with the controller via the roboteq roborun pc utility for windows 8. But somehow this node is unable to connect. I have tried assigning the serial port string("/dev/ttyUSB0") to the serial port parameter of the node using the following line : [rosrun ax2550 ax2550_node _serial_port:="/dev/ttyUSB0"] (&) [rosrun ax2550 ax2550_node serial_port:="/dev/ttyUSB0"] but it too has failed.

I dont know what iam doing wrong. Could anyone please guide me into the right direction. It is absolutely important for me to get this node working.

This is the output from "ls -l /dev/ttyUSB0":

crwxrwxrwx 1 root dialout 188, 0 Feb 28 04:14 /dev/ttyUSB0

And when i run the node with the following command " rosrun ax2550 ax2550_node serial_port:="/dev/ttyUSB0" " i get the same error as specified earlier.

2015-02-18 05:58:57 -0600 asked a question Rosserial tiva-launchpad

Could anyone please tell me how to get rosserial working on tiva connected launchpad. I want to publish Imu msgs over rosserial from my launchpad. I have tried sending data over uart from launchpad to arduino but it is a very adhoc solution and doesnt work entirely. Frankly i would love to get the rosserial working on my launchpad. please do help if you can

2015-02-17 23:57:54 -0600 answered a question Information on message sensor_msgs/Imu

if your IMU is outputting roll,pitch and yaw then your covariance matrix would be a 3x3 matrix. The diagonal elements represent variance of each measurement (eg: if variance of pitch is Ypp, roll is Xrr and yaw is Zyy). Cov[0][0] = Xrr; Cov[1][1] = Ypp; Cov[2][2] = Zyy;

You can also fill out the non-diagonal elements which represent co-variance (how two variables change ). But the diagonal elements themselves should be enough for robot_pose_ekf.

2015-02-05 17:43:58 -0600 answered a question what are the prerequisite for ROS ?

This video will help you get a good overview of ROS. Best of luck :).

2015-02-05 17:35:52 -0600 commented answer IMU ros orientation

@Kristof: According to REP-103 & 105. The body frame is to be oriented (+X- north, +Y-west, +z-up). My imu uses (+Y-north, +X-east, +Z-up). should i be converting these orientations in the imu processing itself or i could somehow convert these notations under ROS?.

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2015-02-03 09:19:30 -0600 asked a question IMU ros orientation

Hello everyone,

This is a 2 part question:

1) I am building a differential drive robot. Which uses encoders and imu to get the orientation of the robot. The imu is an MPU9150 with TM4c1294xl microcontroller. I have successfully fused the gyro and magnetometer via a kalman filter to get an estimate of yaw (referenced with the initial conditions). I want to be able to publish yaw output from my imu via the rosserial package. I will be publishing the yaw output only, so my euler orientation should be (0,0,yaw) right? And which orientation convention does ros use. I am using North-East-Down(NED). I am using udoo board which is running rosserial on its arduino compatible microcontroller. The udoo is connected via i2c to my TM4c1294xl. My question is , does ros provide standard msg type to support euler angles from an imu ? could anyone please point me into the right direction.

2) Would i be better off by tilt compensating my magnetometer rather than just assume that the robot drives on plane surface through out. What are the pros and cons of not implementing it.

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2014-09-07 14:26:26 -0600 commented answer sicktoolbox baud rate

No not really.. hopefully wont be a problem. Just wanted your say on this.

2014-09-07 13:39:09 -0600 commented answer sicktoolbox baud rate
Requesting partial scan data stream.. why am i getting this??..
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2014-09-07 11:35:56 -0600 commented answer sicktoolbox baud rate
Requesting partial scan data stream..

Why does it say partial scan?..

2014-09-07 11:07:55 -0600 answered a question sicktoolbox baud rate

yup got it working. I ripped open the usb-serial converter that i had been using and turns out the chip inside was of some chinese make and wasnt compatible with the ftdi_sio module. After a while i remembered that i had an old serial to ttl logic converter which also happens to be a serial-usb converter. It uses a silabs chip compatible with cp210x. Although i was quite skeptical since it uses a max232 IC to convert the serial signal to ttl levels. But anyhow i connected it and it worked right away.

On a side note though, will the max 232 IC cause me to miss some scans??

2014-09-07 04:20:44 -0600 commented answer sicktoolbox baud rate

okay. I'll try doing that. Thanks alot for your help ahendrix. :) .

2014-09-07 03:20:54 -0600 commented answer sicktoolbox baud rate

[ 421.762333] ftdi_sio ttyUSB0: error from flowcontrol urb [ 2290.997438] ftdi_sio ttyUSB0: ftdi_set_termios FAILED to set databits/stopbits/parity [ 2291.005463] ftdi_sio ttyUSB0: ftdi_set_termios urb failed to set baudrate [ 2291.012692] ftdi_sio ttyUSB0: urb failed to clear flow control

2014-09-07 03:19:54 -0600 commented answer sicktoolbox baud rate

i did the upgrade.. the ABI mismatch doesnt occur now but the baudrate issue is still present. I have checked the cable manually (using multimeter) as well it seems to be receiving the signals properly.Let me show you the output of dmesg | grep tty it might give u a better overview of the situation.

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2014-09-06 15:26:52 -0600 commented question sicktoolbox baud rate

sorryy.. forgot to update them.

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2014-09-06 13:26:33 -0600 asked a question sicktoolbox baud rate


I am using UDOO board and a sick lms 200. I get an error when i run the sicktoolbox_wrapper which says "failed to detect baud rate". If not that the program waits indefintely at startup.

* Attempting to initialize the Sick LMS... Attempting to open device @ /dev/ttyUSB0

the program waits here forever or it says "failed to detect the baud rate". I've tried the same serial to usb converter cable on my x86 machine and it works perfectly. I sometimes get the following error

" * Attempting to initialize the Sick LMS... Attempting to open device @ /dev/ttyUSB0 Device opened! Attempting to start buffer monitor... Buffer monitor started! Attempting to set requested baud rate... A Timeout Occurred! 2 tries remaining A Timeout Occurred! 1 tries remaining A Timeout Occurred - SickLIDAR::_sendMessageAndGetReply: Attempted max number of tries w/o success! Failed to set requested baud rate... Attempting to detect LMS baud rate... Checking 19200bps... ERROR: I/O exception - SickLMS2xx::_setTerminalBaud: Unable to set device attributes! ERROR: I/O exception - SickLMS2xx::_setTerminalBaud: Unable to set device attributes! ERROR: I/O exception - SickLMS2xx::_setTerminalBaud: Unable to set device attributes! /opt/ros/hydro/lib/sicktoolbox_wrapper/sicklms: symbol lookup error: /opt/ros/hydro/lib/sicktoolbox_wrapper/sicklms: undefined symbol: _ZN3ros7console5printEPNS0_10FilterBaseEPvNS0_6levels5LevelEPKciS7_S7_z

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2014-08-24 23:19:46 -0600 commented answer UDOO sicktoolbox

M sorry, i know this is not the place for such questions but i figured you could help me with this. i've tried most of the relevant forums but no replies whatsoever. The kernel version is 3.0.35

2014-08-24 23:18:44 -0600 commented answer UDOO sicktoolbox

I just connected my usb memory stick, i can access the contents. It is being mounted properly but UDOO is not creating a device node for it as well. Could it be a kernel bug or something? or m i missing something here.