Quadbot 17

thingiverse

This is Quadbot 17, an in-progress quadruped robot created as part of a learning exercise using Autodesk Fusion 360. The quadruped robot will use AX-12A Dynamixel servos, which may be upgraded to the more powerful AX-18A. Each leg currently has 20 degrees of freedom, and there are two additional degrees of freedom for the body. The servos and brackets come from Robotis, with some replaced by metal counterparts available from Trossen Robotics. They will be painted to match a specific color theme. The rest of the robot is designed using 3D printed parts in mind, with the main framework of printed parts forming the body sandwiched between 1.5 mm thick custom plates. The unique aspects of this quadruped include its articulated legs, which have more degrees of freedom than typically found on small quadrupeds, and its articulated "spine," which will help it navigate uneven terrain. Several options are being considered for the "head" or main sensor pack: an XBOX Kinect v2 time-of-flight sensor, a Scanse Sweep LiDAR, and an Intel RealSense depth-sensing camera. Currently, a hardware test rig of one leg has been built, and the kinematics have been calculated and tested. A temporary chassis has been constructed using MakerBeam aluminum profiles. The next step is to build the CAD modeled chassis out of aluminum sheets and 3D parts, then focus on achieving more effective walking gaits. A walking gait has also been implemented: a Python test program reads the up/down and forward/back position of each leg for a number of frames that make up a walking gait. The inverse kinematics is solved, and the resulting joint values are streamed via serial over to an Arbotix-M, which simply updates the servo goal positions. The prototype custom chassis is complete! All parts of the custom chassis have been printed in PLA plastic on a FlashForge Creator Pro. The structure is strengthened by pairs of aluminum plates. All plastic parts have been sanded and spray-painted. I threaded the holes on all the 3D parts, which were either 3 mm wide where the aluminum plates attach or 2 mm at the leg and spine bracket attachment points. Using a tap for the 3 mm holes worked well, but the 2 mm holes were more prone to being stripped or too loose, so manually threading the holes with bolts worked better.