Saturday, February 28, 2009
To build a mini robot you need to have small motors to drive the articulation of each joint. In Hubo's case It uses a complex set of multiple motors and drive belts in combination with Harmonic Drive systems to produce movements and have holding torque to stand and move. This method work wonders for Hubo but is not a good system for a small system for reasons that it is bulky and very expensive. On top of the mechanical complexity it needs to have custom motor controllers to drive the motor train as well. Small Humanoids can use a off the self package that includes a motor, gear set, encoder, and controller. These servos are far more cost effective, light weight, and have far less overhead to program the included controller. The servo package we chose for this project is the Robotis Dynamixel. Robotis is actually a Korean based Company that sells robot kits such as the Bioliod Humanoid. They sell many other accessories and servos for people interested in building custom Humanoids like ourselves. We deiced to go with the RX-28 that supplies 28N.m of torque for leg servos and RX-10 (10N.m) for the upper body.
I liked the legs where the knee joint is set on an angle to the perpendicular part of lower leg and foot. This allowed the robot to have a very fluid motion during walking. I also felt it did not have to Throw its leading and trailing leg as far to achieve locomotion.
The second design that also took my interest was a small robot also from ROBO - ONE. This robot is called OmniZero.
The video shows the unique construction of the robot, notice that this robot has two motors at the knee joint. The double knee is much different than most Humanoid robots competing. Most robot have a single motor actuating at the knee, but in using two motors in the knee allows each motor to rotate half the distance. This allows of for faster actuation at the knee and I believe that this is a potential design for a more capable running robot.
Feb. 9th - 11th Finalize Robogames CAD of Legs/ Feet
Feb. 12th - 14th Produce CAM with MasterCam of the Legs/Feet
Feb. 16th - 17th CNC parts at Hubo lab
Feb. 17th - 21st Torso/ Arms Finalize CAD
Feb. 21st - 28th Produce CAM for Torso/ Arms
Mar. 1st - 7th (Overflow) CNC of Torso/Arms
Mar. 1st - 7th Start MasterCam Documentation for tutorials completion April 1st.
Mar. 7th - 13th Rap up loose ends with Hubo 2 CAD and Documentation