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Sensor data via USB

asked 2018-07-23 06:24:22 -0500

S.Yildiz gravatar image

Im working on a project and i want to use a sensor. I can plug in the sensor via usb. I do not need any driver for the sensor. My task is to have an access to the sensor data. I have followed the tutorial on this page: http://clearpathrobotics.com/assets/g... But i dont know if this is my soution. I dont know what to do now. How can i have access to the data in ROS? Do I have to write a wrapper node? If yes, how?

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How can I take raw data from the sensors and publish it to a ROS topic?

S.Yildiz gravatar imageS.Yildiz ( 2018-07-23 06:30:17 -0500 )edit

How do you usually access the data without ROS? Is there a program you run? Or is it like a mouse that you just plug and play? I think you might need a wrapper to capture the stream of data.

bpinaya gravatar imagebpinaya ( 2018-07-23 06:30:38 -0500 )edit

I can have access to the data on windows. I have to install a software(Docklight) and configure the setting for the sensor like the baudrate etc. If i do this i get all the data on the software listed. Yes like a mouse. And how can i write a wrapper? is there any tutorial for this?

S.Yildiz gravatar imageS.Yildiz ( 2018-07-23 06:33:45 -0500 )edit

ROS works on Linux, did you get it to run on Windows? I think you should find how the data is being communicated (maybe serial? in that case check http://wjwwood.io/serial/ ). More info on the sensor would be helpful, but btw if you have to use Windows it seems quite hard to do.

bpinaya gravatar imagebpinaya ( 2018-07-23 08:04:07 -0500 )edit

So it is a sensor for detecting the range between two modules. No, I dont have to use Windows. There is just a software which can read the data supported on windows. And yes the communicatian is serial.

S.Yildiz gravatar imageS.Yildiz ( 2018-07-23 08:19:25 -0500 )edit

Btw I replied down below.

bpinaya gravatar imagebpinaya ( 2018-07-31 02:54:06 -0500 )edit

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answered 2018-07-25 04:29:39 -0500

bpinaya gravatar image

updated 2018-07-25 07:11:52 -0500

Okay with the info provided I think I can sort of give some help. Check this past answer too btw.

So you in order to get the data in ROS, you need to make a wrapper for your sensor, if you know it's serial communication check the serial support for ROS here.

Also the guy from the answer made a nice simple example of ROS serial communication here

From his code:

#include <ros/ros.h>
#include <serial/serial.h>
#include <std_msgs/String.h>
#include <std_msgs/Empty.h>

serial::Serial ser;

void write_callback(const std_msgs::String::ConstPtr& msg){
    ROS_INFO_STREAM("Writing to serial port" << msg->data);
    ser.write(msg->data);
}

int main (int argc, char** argv){
    ros::init(argc, argv, "serial_example_node");
    ros::NodeHandle nh;

    ros::Subscriber write_sub = nh.subscribe("write", 1000, write_callback);
    ros::Publisher read_pub = nh.advertise<std_msgs::String>("read", 1000);

    try
    {
        ser.setPort("/dev/ttyACM0");
        ser.setBaudrate(9600);
        serial::Timeout to = serial::Timeout::simpleTimeout(1000);
        ser.setTimeout(to);
        ser.open();
    }
    catch (serial::IOException& e)
    {
        ROS_ERROR_STREAM("Unable to open port ");
        return -1;
    }

    if(ser.isOpen()){
        ROS_INFO_STREAM("Serial Port initialized");
    }else{
        return -1;
    }

    ros::Rate loop_rate(5);
    while(ros::ok()){

        ros::spinOnce();

        if(ser.available()){
            ROS_INFO_STREAM("Reading from serial port");
            std_msgs::String result;
            result.data = ser.read(ser.available());
            ROS_INFO_STREAM("Read: " << result.data);
            read_pub.publish(result);
        }
        loop_rate.sleep();

    }
}

I think it doesn't get any simpler than that. Once you read the data from the serial port you can use it in your project. Good luck and happy coding!

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Asked: 2018-07-23 06:24:22 -0500

Seen: 251 times

Last updated: Jul 25 '18