OpenSCAD source code for building a large autonomous mining robot. Uses a combination of welded and 3D printed parts.
To build this source code, download OpenSCAD 2020 or newer, and:
git clone https://github.com/AuroraRoboticsLab/AuroraSCAD
openscad Excahaul_latest.scad
The subdirectories contain a variety of subassemblies which are primarily 3D printed, held onto a frame which is primarily welded steel.
This is a side view of the entire robot, in Excahaul_latest.scad, holding the rockgrinder tool.
The overall coordinate system has +Y forward (as required by Unity for simulation), +X to the robot's right, and +Z up. This is right handed.
The base of the robot is the welded steel frame, which is MIG welded from 1 inch / 25mm steel box tubing like most of the robot's fabricated parts. The front wheels bolt directly to the frame for stability, and the middle and rear wheels are on a rocker to conform to the ground. The large rear electronics box also bolts on directly, and the front fork and arm boom are bolted directly on the frame as well.
The robot arm moves via two links. The arm boom connects to the robot frame and provides front-back motion. (The boom coordinate system is aligned with the inertial measurement unit mounted on the shorter angled bar, which is rotated about 25 degrees from the longer bar.)
The second robot arm link is the stick (following the odd excavator naming convention). The stick has an Intel RealSense D455 depth camera mounted on top, and small electronics box for motor controllers and interfacing.
The next link holds the tool coupler. It can tilt the tool forward and backward via linear actuators, and spin the tool via a stepped planetary geartrain.
The tool coupler lets us pick up tools using a 2-pin approach similar to excavator quick-change. The origin is centered on the top pin. The bottom pin can be locked in place with a rather complex linkage wedged inside.
A variety of excavation tools could be used, but the highest productivity tool is a rock grinder, which spins a drum to mill material directly into the front scoop. The large ammo can stores the batteries, motor controller, and has space for cooling oil as well.
We move excavated material around in the front scoop. The fork linear actuator raises and lowers the scoop relative to the frame via this part; the dump linear actuator rides on the fork and pivots the scoop to unload material.
The front scoop has a volume of 50 liters, which lets it carry a payload of about 50 kg of broken-up regolith simulant chips. The coordinate system is rotated by 45 degrees to match the inertial measurement unit on the pivot arm.
This is a photo from the front of the robot, showing our first rough physical prototype.
Each OpenSCAD file has some comments, but we are adding comments and README to make this easier to follow. Please contact lawlor@alaska.edu if you have questions or suggestions!
Unless marked otherwise, these source code files are released to the public domain.