Darwin Op Inspired Mech

I have been working on a new biped (Tychus) for 2 months now. The short term goals for this robot are to have a robust walking gait that can change speeds and a mech warfare payload. Long term goals I am not sure of yet, but may include vision processing, aesthetics, and perhaps even a "running" robot.  


Specs:
Actuators: 21 DOF, 16 RX-28, 5 RX-24F
Processing: 1.6Ghz Fit-PC2I
Board: Arbotix 2
Sensors: Accelerometer and Gyro for dynamic balancing
Camera: USB Webcam Weaponry: 1 Chain-gun, 1 Chainsaw
Framework: Mostly custom designed Aluminum frames/brackets, legs inspired by Darwin OP
Armor: 3d printed shells or Sheet metal armor.
Battery: 4s 2100mAh Thunderpower LiPo
Height: 16" Weight: 7 lbs / 3.2KG


Here is a render of Darwin as it was designed when i sent the parts to get cut.

The design uses all 2mm thick 5052 Aluminum, to reduce manufacturing costs. The entire robot is cut with a laser from a few square feet of material. Here is a photo of the brackets as cut by Fox Valley Metal Tech .

From there I bent them to my design, unfortunitly my brake is at its limit with this thickness which made bending some of the brackets fairly challenging. In the end everything fits though!

Walking is one of the most challenging parts about of bipedal robot, so i began working on that portion first. Eventually I plan on using the fit pc and a arbotix 2 to generate the walking gait, but to get things moving I wrote a spreadsheet that generates a series of poses that can be copied into Roboplus Motion (Robotis software) to test different gait strategies and parameters. The spreadsheet can modify the body shifting distance, leg lifting height, step length, body position, and servo offsets all in seconds, and takes about 30 seconds to copy into the software to try out the effects of the new motion.

After about a week of frustrating tuning, I decided to add rubber soles to the feet of the robot so the feet would no longer slide. In my past experiences with quads, sliding feet help keep the servo's from overheating. In my bipeds case though, this is not true because theoretically the feet do not slide on the floor at all, even when turning. Adding the rubber to the feet instantly gave Tychus a stable walking gait without any further tuning to the walk.

~ Cire