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STAR FISH
A Climbing Robot
For Advanced Robotics (ME 184), the final project entailed designing and manufacturing a climbing robot that could navigate up a vertical pillar. The pillar had variable materials, widths, and shapes, thus requiring significant creativity to accomplish the task. To accomplish the task autonomously, the robotic gripper had to use at least one camera and Digital Image Correlation (DIC), in addition to any other sensors required, to determine the surface’s material, width, and potential obstacles to gripping.
To overcome the obstacles in this project we used the following hardware and software:
Prusa 3D Printer
Laser Cut
SOLIDWORKS
Raspberry Pi
Raspberry Pi Camera
Ultrasonic distance sensor
Hand Tools
Climbing Robot: About
The Challenging Pillar to Climb
Climbing Robot: Gallery
I. The Team
Our group consisted of two Mechanical Engineers and a Human-Robotic Interactions Engineer who has a background in Computer Science. Our interdisciplinary team proved useful throughout the entire product life cycle as robotics is inherently a multifaceted field.
II. Design
Before moving forward with anything, we sat down as a team and mapped out what the challenges of the task included and just how we thought we could solve the problem. Additionally, we shared various concepts of climbing robots already in existence for initial inspiration.
Here you can have glimpse of our SolidWorks model of our idea:
Climbing Robot: About
III. Manufacturing
Due to the short turn-around of the project, 3D printing and laser cutting were our main methods of manufacturing. Unfortunately, the limited access to available (and working) 3D printers proved difficult for every team, including ours.
For the final product, we printed everything besides the rack and pinion, the threaded and stabilizing rod, and the main bodies. We preferably wanted a strong metal for these items and luckily, after a thorough search in the Tufts machine shop, we found the perfect metal racks and rods for our system. This changed our design just slightly fairly close to the deadline. Without enough time to reprint the main bodies, we opted for a 2D laser cut version.
Here is a picture of our final product that has the metal racks, laser cut bodies and 3D printed arms:
Climbing Robot: About
Finalizing the manufacturing
Climbing Robot: Gallery
IV. Programming and Operation
The programming side of this project was structured in a hierarchical fashion, which allowed higher-level functions to carry out an autonomous climbing algorithm by calling lower level functions which controlled individual motors and read data from the various sensors. An example of a lower level function might be shoulders_in1(), which causes the upper two arms to rotate into their gripping position. An example of a higher level function which makes use of shoulders_in1()would be move_top(). This function brings together a sequence of body movements in the robot, which caused the top gripper to release from the pole, move upward via the threaded rod for 10 seconds, and attempt to grip. This grip attempt function, try_grip1(), reads data from ultrasonic sensors which determine whether there are any obstacles in the way of the gripping point. If obstacles are detected, the function recursively calls itself and moves up for another 10 seconds to try again. If no obstacles are present, the arms are activated, via shoulders_in1(), and contracted until the arms are pressed against the pole (according to data read from the same ultrasonic sensors). Snippets showing the hierarchy from motor assignment, to the low level functions (e.g. shoulders_in1()), through the intermediate functions (e.g. try_grip1() and move_top()) up to the top level function auto() are displayed below (in order from upper left to bottom right).
Climbing Robot: About
The Code
Climbing Robot: Gallery
Here is a video of working grippers
Climbing Robot: Gallery
Climbing Robot: About
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