Elbow Mod Update

Since the last update I have fixed numerous bugs the navigation errors where due to a damaged encored disc and the arm jitter was due to mismatched names in the Joint state publisher. one of the requirement for ROS MoveIt is a follow joint action server this now works I was ready to start using MoveIt then the elbow worm broke again, the printer not working at this time so I incorporated the elbow mod into the robot.The original idea was to use a MXL belt but the weight and acceleration  cause the belt to slip, after a change to #25 chain and sprocket to operation was better. One side affect of this mod is the arm can droop down which on power on causes a sudden jerk as the arm moves to start position. A simple adjustment to the start position and to place the arm into the tuck position for driving will be required, maybe a spring to hold the weight   will also help.

Inmoov arm and ROS MoveIT

This is the start of my efforts to run the Inmoov arm with ROS MoveIT. I have had to make some changes to the inmoov arm. ROS requires feed back and the servos used don't have feed back I tried to attach a wire from the Potentiometer to the adruino but this proved unstable and the servos were weak I replaced the servos with gear motors and a controller board all position readings and angle requests are done via I2C thru a master arduino.

First task is a URDF model  I'm only using 1 arm with only 4 joint to start
launch the model in RVIZ and make sure the model moves as expected the adjust the real robot to match the model (or simulation wont work as expected)

 next task run moveit setup assistant
 " roslaunch moveit_setup_assistant setup_assistant.launch"
I had to run this on the robot not a remote session.  I follow the  tutorial just using the default settings. After saving the configuration file (don’t forget to add the directory to the package path) it's time to test in simulation.

Simulation
I the launch files generated there is a demo mode launch that and maximize the rviz window. I the motion planning tab go to planning set a start position and a end position(random) then run the arm will move to the new position   cool!

next 
add some obstacles to the scene and see how the arm reacts


to be continued 

Using Howie Chatbot with ROS

Using Howie Chatbot with ROS

This is a bare minimum script to run Howie in ROS it wont use voice recognition yet and uses festival for text to speech. I use Ubuntu 12.4 with ROS groovy and rosbuild not catkin you need to Create a ROS Workspace using the tutorial from here http://wiki.ros.org/ROS/Tutorials/InstallingandConfiguringROSEnvironment

Install festival with your package manager

Install the supplied files in you ROS workspace do a rosmake in the top level of each 

directory. In a terminal window type “roslaunch howie_ros howie.launch” 

Change to the nodes directory and in a terminal window 

run“rosrun howie_ros robbiei.py”

If it all works in the terminal_input window type in “what is you name “ and in the other terminal you will see the response. If it doesn't understand the question make sure you run robbie.py in the nodes directory if festival is configured correctly you will also hear the response.

You can change the name of the bot in robbie.py

This is more of a hack than any thing else

regards

Peter

 archive

Inmoov elbow

In a effort to get more out off the inmoov arm I have made some mod these mods are still experimental looking at the NASA robonaut the shoulders rotate back and give almost 270 degrees of rotation by pulling the shoulder back it makes it easer to drive around, tucking the arm up and being able to lock them in place which will help with the bounce when going over small gaps . Part 2 of the mod requires the elbow to move more than 90 degrees I was never a fan of the old thread design having broken a few also I need feed back using a motor and pulleys I'm able to get the required movement and using the same motor controller as the rest of the arm also helps keep it simple. Todo move the motor lower  to increase the up angle  and smaller motor this one is only at 1/3 power and speed.

Driving

The improved base is now fitted and working well the rear castors will need to be replace as they don't turn freely. After generating a new map, Navigation works but I haven't tuned it yet out of the box localization is within 200mm after a 10meter loop
with a couple of loops. Encouraged by this I made a launch file to start all the systems
on Robbie with the plan to do a endurance test in the near future something involving a roving patrol and charging the batteries when required. Driving Robbie
around the lounge room and kitchen there is only 10 cm of gap between the walls
and the shoulders. Instead of controlling the motors using a RPM method I now use
distance per timing frame the main advantage is both wheels move the same distance making it easier for navigation. In the video Robbie is driving under remote control I need to work on the movie making skills. The next step is navigation runs.
After repeated test of the arm the original part are staring to fail some due to problems I had when I first started printing (poor quality ) and other while adjusting the new motors the plastic parts tend to break when the joint PID controller oscillates or travels too far to fast.

First arm test

Just a quick video of the right arm, testing the shoulder tilt and lift motors. The good news is it held up and nothing broke or burnt out the lift motor only goes up half way  at the moment I have to reset the pot zero and change the start point and adjust the PID controller for the weight of the arm but the speed of the lift is good and the tilt is a bit slow I have to change the gear ratio from 3:1 to 2:1 but that is for the next model actuator. Part of the test was to compare directions of the real robot to the model in RVIZ the tilt axis is reversed and lift is going the right way and the angles look close next test will be with all the servos and the lift with full travel.
The base is not very stable but the new base is almost finished and is shown in the model in RVIZ

Fails

It's been a hard couple of weeks the new base needs a wider foot print it's not very stable when moving making the kinect laser scan is unreliable but the worst part was the new dog wanted to say hello by jumping up on him which resulted in Robbie falling over the good part was most of the upper torso was off so very little damage was done. With the battery charger on board and hooked to the battery all the time this discharges the battery when not in use for a while. So after a bit of a rethink I I'm rebuilding the drive base with bigger wheels a wider base and better weight distribution also added a charge bar so charging can be done from a docking station.
 Finally had so time to play with arms today  I was really happy with the moving the shoulder lift( the joint with the most strain) was moving nice and smooth through the full range of movement but when I tried a fast full range movement the drive coupling broke again if I could join the 2 STL file's (Freecad just crashes) I would print them in nylon