Project Logs

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• HIGH speed movement

  Petar Crnjak • 7 days ago • 0 comments

  In this video robot is moving from point to point with acceleration and deceleration. This makes it start and stop smoothly without jerky motion.

• Video of motor jogging!

  Petar Crnjak • 03/25/2021 at 16:01 • 0 comments

  
  
  

• Kinematic diagram of the robot and Denavit-Hartenberg parameters

  Petar Crnjak • 03/12/2021 at 18:01 • 0 comments

  So this is a kinematic diagram of the CM6 robotic arm. you can see that robot has a spherical wrist since axes Z5, Z4, and Z3 always intersect. 

  And here is DH table!

  I also always like to have written what does every parameter mean since I forget every time so here they are! :D

  Link offset = distance Zi-1 from Oi-1 to the intersection with Xi.

  Link Length = Distance from Oi-1 and Oi measured along Xi

  θ THETA = Rotation around Zi-1 to get Xi-1 to match Xi

  α ALPHA = Rotation around Xi to get Zi-1 to match Zi (We are rotating frame Oi-1 around Xi)
  

• First video of CM6 in action!

  Petar Crnjak • 03/07/2021 at 12:06 • 5 comments

  First video of CM6 in action! Here you can see joint 1 being used as master and joint 2 as a slave (joint 1 is disabled, so it is really easy to move it). Atm, I only wired up the first 3 joints, and the software I wrote is configured for 3 DOF arm so there is a lot of work there. I tested multiple control techniques and one in this video works best and smoothest. In the future, I will show you other techniques I used but they did not perform as well as this one.

• Total assembly!

  Petar Crnjak • 02/26/2021 at 19:05 • 0 comments

  I finally assembled the arm! It is looking really promising but everything will be revealed when I start some hardcore testing! Here are some pictures :D

• Assembled base (Joint 1 and 2)

  Petar Crnjak • 02/25/2021 at 16:25 • 0 comments

  Assembled the last parts of the robot. Now the only thing left is to put it all together and start testing and playing around with it. Joint 1 these pictures is using 8:1 planetary gear reduction and joint 2 is also using 8:1 planetary reduction.

• Upper arm + forearm

  Petar Crnjak • 02/24/2021 at 11:18 • 0 comments

  So this is assembled forearm and upper arm. So upper arm is using aluminum extrusion to connect joint 3 with joint 4. By using aluminum extrusion we can lengthen and shorten the arm and change the reduction ratio of joint 3 by changing a few parts. The length of extrusion in this picture is 200mm. Gear reduction of joint3 is 8:1 planetary gear ratio and then 32:28 belt reduction. The total reduction of joint3 is 9.14285:1.

• Forearm assembled

  Petar Crnjak • 02/23/2021 at 16:36 • 0 comments

  So this is a complete forearm assembly. It is still looking pretty clean because there are no wires but once it is wired up wires will be visible. 

  Joint 6 is 5:1 planetary reducer. Joint 5 is plantery 6:1 and join 4 is 6.5: 1 bevel gear + HTD M5 belt. 
  

  as you can see here joint 5 is using a 2:1 bevel gear reduction and after that 3:1 belt reduction. Total reduction is then 6:1.

• Gallery of robot renders

  Petar Crnjak • 02/22/2021 at 15:54 • 0 comments

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