Thursday, 14 July 2016

Magnetic encoder gearbox


It's been a while since the last update I have redesigned the gearbox with 2 radial bearings and a thrust bearing. The worm is print in 2 parts this gives a better tooth profile and reduce backlash. The motor driver is now a VNH2SP30 on a custom pcb and still the arduino pro mini. Its now mounted on the gearbox to reduce wiring and make it more modular. After the redesign its not 100% compatible with Inmoov. Communication is now with RS485 each unit is daisy chained from the last again to reduce the wiring clutter. Using cheap motors causes a problem with the PID accuracy mainly due to the higher starting voltage and the resultant jerk on start of movement.


Saturday, 19 December 2015

Magnetic Encoders

Robbie is now fully functional again after his computer problems the reason the arms missed commands was due to the controllers resetting. after I supplied power to the USB hubs every thing worked as required.
To increase the accuracy of the arm I started replacing the potentiometers with magnetic encoders to fit the new encoders required a few modification to the gearbox, I incorporated a bearing in the top of the gearbox and a mount for the magnet in the drive gear plus a few extra tweaks to increase the strength of the assembly not all modification will be fitted at the same time some will wait until the next major rebuild

Moveit Update
Robbie's moveit configuration is working again accuracy is 15 cm not very good but magnetic encoders will help plus a better calibration. Obstacle avoidance suffers because planning only just misses the obstacles. Robbie now has a point at node where he will point to a published target pose.

Face recognition
We are now running the COB face recognition package this works well in daylight but the garage is to dark Robbie makes a few errors, I need to add more lights. The AI will say Hello when he first recognises a face then after 5 minutes he will just say Hi. The name of the recognised face is returned to the chat bot so he knows who he is talking to

Object recognition
will recognise a pre programmed object but wont learn a new object because ECTO requires direct access to the kinect driver Freenect uses a different driver and Openni will not work under indigo
2d recognition, shift and surf and not included in the opencv package so its very flaky

Navigation
Increasing the Global inflation will make Robbie plan further away from obstacles.

Autonomous operation
shutdown command will not work when Robbie is started using robot upstart also depth registered points from the top kinect will not always work unless something uses it straight away the lower kinect has the point cloud to laser scan and gives no trouble. I will start face recognition on start up and see if it remains stable. We haven't had any jitters or strange events since we started using the powered hubs for the arduinos. The current high temperatures are causing a few resets I need a bigger fan and more vents in the CPU bay

Robbie's Emotion system
has been turned off for the moment since he spent most of the time bored and kept quoting a markovian chain from Sun Tzu. It needs a lot more configuration and thought but its fun for a while

As the design of Robbie matures I'm starting to add covers to hide the wires and keep dust off electronics but this has induce a few extra problems
  1. Heat build up
    more fans need to be included in the design
  2. striped out threads
    printed PLA and MDF wont hold a thread for very long so now I will add M3 threaded inserts and M4 rivnuts to the structure




Tuesday, 15 September 2015

AI Updates

Robbie's computer is still broken so I was able to catch up on some tasks I never had time for.
The potentiometer were never very accurate I have designed magnetic encoders as a replacement they are more accurate and and just plug in the the existing structure they will be fitted on the next rebuild.

The overall control was a very hard to maintain and expand natural language is not very good with robot control some verbs are shown as nouns thus wont be interpreted as commands. In NLTK you can define what words are verbs or nouns but maintaining the files is troublesome, I tried pattern_en but it suffers from the same limitations. I also tried WIT a online language processor the learning curve is too steep and I wanted a local solution. Robbie's chat engine on the other hand works well.

I never really looked into pyaiml's capabilities but it can run system programs with command line args. For testing I reduced the loaded aimls to two one for commands the other for general response.
Of course that just puts me back to where it was before but with a lot more potential. Pyaiml will throw a error message for a unknown command I made it so it will append the command to a aiml file I only have to add the meaning later I can automate this but for now I want control over it, this sort of gives me a learning robot.
One of the intriguing possibilities is to query Knowrob ontologies.
For now I can add the name of a person from the face recognition node.
Next task is to make a semantic map and name the objects so when asked his location Robbie will answer “near the desk in the garage” not x,y,z.

All of Robbie's physical task are now controlled through behaviour trees program with action servers any task can be pre empted and resumed if there is a fault or error condition. The behaviour tree also monitors and controls Robbie emotions tasks will give pleasure doing nothing will result in boredom, when boredom reaches a certain level Robbie will do a random task that varies from uttering a quip using a Markovian chains, moving his head or arms to driving around in circles.
Using simulators like Rviz and Gazebo has made these tasks much easier.

Thursday, 18 June 2015

Robbie Upgrade



The original base was causing some problems with arms in the relaxed and travel position the arms
would hit the lower body , I don't want the arms to make Robbie to wide he has enough trouble getting through door ways as it is also I didn't have the time for a total rebuild (moving the wheels further inboard) so I opted for some covers and a redesigned waist joint. I ripped the speakers apart

and put them in the space for the kinect. I have put the kinect back in the head so I can visualise the work space  




Monday, 6 April 2015

Autonomous Update 2

For a robot to be autonomous it must be easy for others to operate it logging in and having to run some launch files is never going to work. The answer is upstart we tried this a few time but it never worked as expected. The version that comes with indigo works now to start Robbie you just have to turn him on. Then you can control Robbie with voice commands or Rviz off course with the greater reliance on voice commands we need to expand his capabilities.  One of the options is show time which demonstrates his capabilities in a continuous display, good for showing off  to visitors. Other commands will be included over time. The original NLTK is showing its age now Pattern_en shows a lot more promise but with a steeper learning curve

Tuesday, 31 March 2015

Get Me a beer

This is Robbie's first simulation run of picking up a object of a table moving it to another table, then 
returning to his station. The simulation didn't show the object attached to the hand but the hand opens and closes in the right position


Wednesday, 11 March 2015

ROS MoveIT Update

I have had Moveit working for a while now but I could never get pick and place work I could
move the arm to a location but that was it. After a bit of research I traced the problem to my
URDF, I didn't place to coordinate frame at the end of the joint and the orientation of the frame
was wrong. After I adjusted everything it worked the arms can now reach more places and the resulting  arm position is more natural. the only real problem is the simple URDF I made for
testing works quicker and has a better result with pick and place(less fails). Next up is a test with
the real robot I have to change the joint configuration on Robbie to match the URDF the wrist yaw joint worked better than the wrist pan joint now the arm has 7 joints plus the gripper not the 8 from before

video