Sunday, 10 March 2013

Fixing the rats nest

Tried to make some videos but Robbie was very unreliable the servo worked then they stopped if you rattle the wire then it worked then the lift motors stopped
clearly its a wiring problem and now is the time to fix it for good. So  i started making PCB's for the various systems each actuator will have its own controller and motor driver connected via I2C  so i need 4 motor controllers for the arms and 8 for the base.

The bottom board is dual sided and will be a combined arduino and l298 motor drive
delivering 6 amps peak. The top middle is just a motor controller it works i just need to add the diodes before it can been used.

The PCB's were manufactured using the toner transfer method the only real problem is the pot and bottom layers are not connected so parts need to be soldered on the top and the bottom this is a small problem with ic holders I just design the boards
with the IC's just having connections on the bottom

Wednesday, 6 March 2013

Robbie get a head

Well sort of it just the neck at the moment and the shoulders don’t look right  but the new shoulder joint will come later. The head pan and tilt servos have been replaced
with dynamixel AX12's

Sunday, 3 March 2013

Harmonic Drive

Well as expected the first version of the drive failed the flex spline cracked.
Reasons for failure are
  • the bearing race is unreliable and dosen't run true causing the drive to miss steps
  • Flex spline the blue ABS is brittle will try with the yellow (its more elastic )
  • wave generator bearing were in fact only PLA bushes  they worked fine but the need to be 1mm taller

Next test will be with the new bearings


Robbie is looking a little plain theses days the kinect as a head is not very interesting to look at so I started to print Inmoov's head to give him a more natural look . One of the changes i made is to replace the standard servos with Dynamixel servos so we can keep the head tracking  and general movements without rewriting a lot of code.
The gear on the bottom was just for holding but I think having the waist rotate will be a advantage Next step is integration