6DOF-Manipulator-Hardware

This repo contains controllers and ROS code for connecting with the hardware on the robot arm.

Install

First clone or copy this repository into your workspace src.

$ cd /path/to/workspace/src
$ git clone https://github.uio.no/INF3480/crustcrawler_hardware.git

Then clone DynamixelSDK into src

$ cd /path/to/workspace/src
$ git clone --branch 3.7.0 https://github.com/ROBOTIS-GIT/DynamixelSDK.git

Build

After installing the repository and dependencies (make sure all ROS dependencies have been resolved), build as usual.

# Or `catkin build`
$ catkin_make

Usage

Use the launch file control.launch to run the necessary ROS nodes. The main configurations for the launch file are control and full_arm. The first selects the controller manager to utilize, available are [trajectory, position, velocity, effort], and the later controls how many joints are connected to the arm, full_arm:=true when all joints are connected and full_arm:=false when the marker is connected.

Enable

After successful launch one has to enable the arm as torque is not enabled when the code is run.

The following will enable the arm (commands will now be executed) and torque is applied.

$ rostopic pub -1 /crustcrawler/enable std_msgs/Bool true

To disable torque run (be careful the arm will fall):

$ rostopic pub -1 /crustcrawler/enable std_msgs/Bool false

** Shutting down the node will also disable torque! **

Controllers

To be a good ROS citizen this package uses ros_control(and ros_controllers) for command controls. The respective controllers and their capabilities are documented elsewhere, but for most users the joint_trajectory_controller should be the first place to look.

Examples

Useful for using the pen and MoveIt:

$ roslaunch crustcrawler_hardware control.launch full_arm:=false
control:=trajectory

Useful with the full arm and custom effort controls:

$ roslaunch crustcrawler_hardware control.launch full_arm:=true control:=effort

Troubleshooting and updates

This will be especially relevant if you are making the 6DOF version.

These are all troubleshooting experiences when working on this hardware repo with Ubuntu 18.04, but will probably be applicable to other setups aswell.

Before you start doing anything, make sure all servos are protocol 2.0 (and not 1.0):

• Download R+ Manager 2.0
• Open it and go to Update & Test and check one and one of the servos.
• If there is servos that are 1.0, connect them one at a time and update the firmware by going into Firmware Recovery, not Update & Test!
• Follow the steps and take in and out the 3 pin TTL connector from the servo when you'r asked to disconnect the servo.

Remember to update the Baudrate, ID and other settings (that you have changed) after the protocol update, because all these will be reset.

You are now set for connecting all servos together and try out the hardware.

When connecting to the fully assembled robot, you may get this usb error:

[PortHandlerLinux::SetupPort] Error opening serial port!

Then run:

sudo chown yourUserName /dev/ttyUSB0

Assuming your USB is connected at ttyUSB0.

Further, you may get this error:

[ INFO] [1532011582.824068948]: Crustcrawler hardware initialized
Error reading from servos, error: -3001
Error reading from servos, error: -3001
Error reading from servos, error: -3001
Error reading from servo: 4, error: -3001
Error reading from servo: 5, error: -3001
Error reading from servo: 6, error: -3001

which is a communication error.

The first fast thing to check is that the latency may be to high. Set it to 1 (it's originally 16) by running

echo 1 | sudo tee /sys/bus/usb-serial/devices/ttyUSB0/latency_timer

and then yo can see that

cat /sys/bus/usb-serial/devices/ttyUSB0/latency_timer

gives you 1. Also dmesg can be useful to check the connection status of the USB.

If none of this helps and the 3001 error still is making your head hurt, there is probably a bad connection or a faulty/broken wire somewhere.

1. Check that all the wires male plugs are connected appropriatly.
2. Open R+ Manager and go into Update & Test. Test the whole connection by having all servos connected. You should see an image like this:

if not, connect one and one (or two and two) servos and set correct

• ID
• Baudrate

3. If all ID's and Baudrates are correct, and you are still not getting up the whole chain of all the servos (like over), try to disconnect one and one of the servos, starting with the last. Hopefully you will get a chain of at least two servos. Try to get as long a chain of connected servos as possible. In this way you can isolate the faulty cable.

Good luck!

Feel free to check out the documentation on MX-64 and MX-28 for any adresses, values and system requirements.