karlhm76's profile - activity

Ok. It took some doing but I was able to get it to work, at least, glxgears works inside a docker container and renders

Ok. It took some doing but I was able to get it to work, at least, glxgears works inside a docker container and renders

@marguedas Thanks for this. I was able to install rocker and running your command got it to build the image, but it seem

I'll give rocker a try now and see how I go, thanks.

Hi, everything exists on the same machine running focal desktop clean install. I have installed build-essential and dock

Docker ROS with X11 output Hi, This seems to be a fairly complicated thing to do. I want to set up a docker ROS develop

Docker ROS with X11 output Hi, This seems to be a fairly complicated thing to do. I want to set up a docker ROS develop

ROS environment in Docker with X11 Hi, This seems to be a fairly complicated thing to do. I want to set up a docker ROS

This is very useful information. Thanks so much

I've decided to look into writing an action server for FollowJointTrajectory.

See how it goes I guess. Thanks again.

I've been having a few problems with getting started with the trajectory action server and catkin and netbeans. Not relevant here though. Even though I've made good progress with the setup I'm still fairly new at this.

Thanks for the info. Yes I've been reading about this. I was simply trying to get the thing to work as easily as possible. I was reading that the fake controller published joint states and i already had something that worked with them, or so i thought.

Hello,

I have a custom 6DOF arm that I'm trying to interface with moveit. I have created the URDF and the model, and I have loaded it into rviz.

I have made a lot of progress with it I think. I'm using ros indigo on ubuntu 14.04

I subscribe to the joint_states topic on my arduino. Using the arduino code I am able to individually control each joint using the joint state sliders when I run the display.launch

I've completed the moveit configuration and it loads with no problems in rviz, and I can plan movements, etc.

however when my arduino subscribes to the joint_states topic at this point, I get errors in rosserial saying [ERROR] [WallTime: 1479872259.522084] Message from ROS network dropped: message larger than buffer.

What is different with these messages than the ones generated from display.launch?

I performed some investigation and found something interesting:

This is the message from when I use moveit demo.launch

header: 
  seq: 954
  stamp: 
    secs: 1479873407
    nsecs: 957350015
  frame_id: ''
name: ['shoulder_base', 'upper_arm_shoulder', 'elbow_upper_arm', 'forearm_elbow', 'wrist_forearm', 'gripper_wrist', 'left_jaw_gripper', 'right_jaw_gripper']
position: [4.435017290525138e-05, 9.012486469545027e-05, 3.372531827300197e-05, 5.395870120266208e-05, 4.7403243313592324e-05, 0.8750411991072651, 0.0, 0.0]
velocity: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
effort: []

and this is the message when I use display.launch

header: 
  seq: 228
  stamp: 
    secs: 1479873728
    nsecs: 257888078
  frame_id: ''
name: ['shoulder_base', 'upper_arm_shoulder', 'elbow_upper_arm', 'forearm_elbow', 'wrist_forearm', 'gripper_wrist', 'left_jaw_gripper', 'right_jaw_gripper']
position: [0.0, 0.0, 0.0, 0.0, 0.0, 1.2491756999999999, 0.0, 0.0]
velocity: []
effort: []

why the differences, and more importantly, can I make the position data the same data types/precision?

I got it working. seems like my baud rate wasn't fast enough.

the arm is also very slow to respond to changes in position. I suppose this is because of the speed of the connection. I am running at 115200.

Hello,

I have connected my custom built robot arm to my arduino using adafruit PWM. I have tested subscribing to a simple UInt16 topic and manually publishing a message to move a servo. It works.

Now I want to link the arm to rviz. My goal is to use the sliders to move the joints on the screen, and have the real arm move as well.

This does not work at all.

The problem seems to be my callback on the arduino is never called. I have no idea why. It could be because no messages are getting there, but I do echo the joint_states topic in another window and I see the numbers changing as I slide the sliders. I'd expect these to arrive at the arduino as well?

It could be a problem with my arduino code setup, even though it worked with the simple subscription, it may not work with the more complex one. It is below.

Or maybe it is something else entirely.

(I have some problems with joint orientations in my model, with the intention of recalibrating the model properly at some point. So please ignore the dodgy code to convert radians to degrees)

Also I am only attempting to move one servo at this point, which is plugged into the adafruit at position 0, but this relates to joint 5 in the arm.

#include <Servo.h>
#include <ros.h>
#include <std_msgs/UInt16.h>
#include <sensor_msgs/JointState.h>

#include <Wire.h>
#include <Adafruit_PWMServoDriver.h>

ros::NodeHandle nh;
Adafruit_PWMServoDriver pwm = Adafruit_PWMServoDriver();

#define SERVOMIN  120 // this is the 'minimum' pulse length count (out of 4096)
#define SERVOMAX  560 // this is the 'maximum' pulse length count (out of 4096)

#define BASE_SERVO 0
#define SHOULDER_SERVO 1
#define ELBOW_SERVO 2
#define FOREARM_SERVO 3
#define WRIST_SERVO 4
#define WRIST_ROLL_SERVO 5
#define GRIPPER_SERVO 6

#define VELOCITY 0.1

double targets[6] = {90,90,90,90,90,90};
double positions[6] = {90,90,90,90,90};

void servo_cb(const sensor_msgs::JointState& cmd_msg)
{
  digitalWrite(13, HIGH);
  targets[0] = radiansToDegrees(cmd_msg.position[5]);
  digitalWrite(13, LOW);

}

ros::Subscriber<sensor_msgs::JointState> sub("joint_states", servo_cb);

void setup()
{
  pinMode(13, OUTPUT);

  pwm.begin();
  pwm.setPWMFreq(60);  // Analog servos run at ~60 Hz updates

  //nh.getHardware()->setBaud(57600);
  nh.initNode();
  nh.subscribe(sub);

  MoveServo(0,90);

}

void loop()
{

  // move towards target at speed velocity
  MoveServo(0, positions[0]);

  if (positions[0] < targets[0])
    positions[0] += VELOCITY;

  if (positions[0] > targets[0])
    positions[0] -= VELOCITY;


  nh.spinOnce();

}

void MoveServo(int servoNumber, double angleInDegrees)
{
  uint16_t pulselength = (uint16_t)map(angleInDegrees, 0, 180, SERVOMIN, SERVOMAX);

  pwm.setPWM(servoNumber, 0, pulselength);
}

double radiansToDegrees(float position_radians)
{

  position_radians = position_radians + 1.6;

  return position_radians * 57.2958;

}

Renamed the joints and success! Thanks for all the help.

Thanks I'll give it a try, i don't want to redo the whole model.

Looking closely i can see now that position 45 in that string is the - in the name. I was thinking it was the value it was referring to.

Cheers!

Thanks I'll give it a try. I don't want to redo the whole model.

On looking closer, position 45 is the - in the name ot is having the issue at.

Cheers!

Unless there is an easier way, I think the fastest way to resolve this is to reconstruct my solidworks model so all servos are in the 0 position to begin with, rather than the home position

Then, the home position can be created as a pose later on.