Multipurpose Mobile Manipulator MkII

(Author's note: Instructable is a work in progress! More detailed descriptions of the steps will be written over the course of the following weeks, complete with links and files. This message will be removed when this Instructable is fully finished.)

The Multipurpose Mobile Manipulator is back, and it's bigger, better, and stronger than ever before! Introducing the new Mark II: the DIY giant robot that does everything, such as playing the piano, delivering coffee, drawing pictures, and more. The Multipurpose Mobile Manipulator Mark II is an advanced mobile robotics platform for students, educators, artists, hobbyists and researchers alike.

Introduction:

• Why we made it
• Features
• Future Work
• Special Thanks

Quick Links:

• Jump to Parts and Equipment
• Jump to Assembly (Base | Chest | Arms)
• Jump to Software
• Jump to Videos

Further Documentation:

• Official website: http://www.choitek.com
• Forums: http://forum.choitek.com
• Source: ( in progress, please be patient with us! :) )

Robotics has the potential to change the quality of human life in unimaginable ways. We wanted to speed up the research and development by making large robotics more accessible. So, back in 2015, we built a research-grade, open-source mobile robotics platform that anyone can build, the Multipurpose Mobile Manipulator Mark I.

Crafted out of laser-cut plywood and a medley of adaptable 3D printed grippers, the robot is capable of performing virtually any human-size task, such as watering plants, playing piano, delivering bagels, and more.

Admittedly, while the robot did not do any single task particularly well, it was incredibly good at teaching and inspiring students. Seeing this, we worked hard to turn our robot into a full-fledged educational technology platform, building upon everything we learned from last year. The result? After one year of additional development, the Multipurpose Mobile Manipulator is now the Mark II, back for round two!

Like its predecessor, the Mark II is an advanced research-grade mobile manipulator platform, designed with modularity, accessibility, and compatibility in mind:

Modularity

• The base, arms and chest can be attached and detached for easy transportation and storage.
• There are plenty of mounting holes to add custom sensors and electronics.
• The top can run independently of the bottom and vice versa.

Accessibility

• Open source software gives users unlimited freedom.
• Open hardware lets users understand how the robot works.
• Laptop-for-a-face simplifies the testing and development pipeline.
• Arduino Mega makes interfacing with the robot's electronics a snap.

Compatibility

• The robot is compatible with Windows, Mac and Linux.
• Libraries for Python 2.7, Arduino and ROS are currently supported.
• Libraries for Unity, Processing, MATLAB, C++, and Scratch are planned.

The Multipurpose Mobile Manipulator is a work in progress, and many more improvements are constantly in the works by Choitek, a new robotics startup in Pittsburgh, Pennsylvania, USA. Here are a few of the things we've improved, and some new things we are currently working on:

New features for the Mark II

• Aircraft-grade aluminum body
• Improved gripper adapter plates
• Keyframe-based robot animation system
• Marker tracking computer vision software
• Simultaneous localization and mapping system
• Arduino Mega 2560 Mark II Controller Shield PCB

Planned features in the works

• Libraries for Unity, Processing, MATLAB, C++ and Scratch
• Standard Firmata compatibility
• OSC Robot Simulator
• SCARA Configuration
• In-depth curriculum
• Lots more tutorials
• More gripper files
• Robot face editor

The Multipurpose Mobile Manipulator Mark II is made possible in part by generous support from the following programs, organizations and initiatives at Carnegie Mellon University:

• Project Olympus
• CMU Robotics Club
• NSF I-Corps CMU Branch
• CMU Undergraduate Research Office
• Frank-Ratchye STUDIO for Creative Inquiry
• Henry Armero Memorial Award for Inclusive Creativity

Please note that the project represents the views of the author and not those of the programs, organizations and initiatives mentioned here.

Access to a variety of heavy fabrication equipment and various small hand tools are required in order to fully build this robot from scratch! Many of these tools can be dangerous if used improperly, and it is highly recommended to either get familiar with the tools listed below or to enlist the aid of someone already experienced with them. Remember that you are following this Instructable of your own accord: the author of this Instructable is not responsible for any unfortunate circumstances that may arise from building this project.

Heavy Fabrication Equipment:

• Plasma Cutter (note that your standard laser cutter probably can't cut aluminum!)
• 3D Printer
• Shop Drill
• Band Saw
• Belt Sander

Small Hand Tools:

• Assorted Screwdrivers
• Assorted Hex Keys
• Soldering Station
• Assorted Pliers
• Wire Strippers
• Wire Cutters
• Hand Drill
• Heat Gun
• Hammer
• Clamps
• Files

Understandably, most folks do not possess the resources to produce a Multipurpose Mobile Manipulator Mark II on their own (machine shop, industrial plasma cutter, et cetera), and working full time, this project is expected to take at least one entire month to build from scratch (part time, it may take far longer). For this reason, we plan to manufacture easy-assemble kits so that everyone can be a part of the growing robotics movement. If you are interested, please join our mailing list and/or contact us directly, and we will let you know when we are ready to move forward. As a company, we still have very much to learn, and we will do our very best to keep things as open as possible for everyone.

Here is a comprehensive list of all of the parts needed to build one Multipurpose Mobile Manipulator Mark II, separated by components for control, actuation, power distribution, and raw materials. The estimated cost for all parts is estimated to be roughly 2500 USD, more or less depending on the suppliers chosen and the materials already owned. (Almost half the costs are in the laptop chosen and the estimated plasma cutting expenses for the aluminum plates.)

Control:

• 1x Laptop computer
• 1x A to B USB Cable
• 1x Arduino Mega 2560 R3
• 1x Dual 12V DC Motor Driver
• 1x Choitek Mark II Controller Shield
• 2x HC-SR04 Ultrasonic Rangefinders
• 10x 3ft Servo Extension Cables
• 8x Nylon spacers
• 2x 80mm Fan Guards
• 2x 80mm LED Computer Fans
• 1x 5ft 5pin Wire Extension

Actuation:

• 2x 4in Wheels
• 2x 8mm Wheel Hubs
• 2x1x2 1/2in Swivel Plate Caster Wheel
• 2x 12V High Torque DC Gearmotors
• 10x Standard Hobby Servos
• 4x Large Hobby Servos

Power Distribution:

• 2x 12V 8AH Sealed Lead Acid Battery
• 12V Sealed Lead Acid Battery Charger
• 12V to 5V DC Step Down Voltage Converter
• 10x 2ft Red and black 18 gauge wire pairs
• 3x Rocker Switch SPDT 10A
• 1x Heat Shrink Tubing Set
• 1x Terminal Block Bus Bar
• 1x Red Emergency Stop
• 5x XT60 Connector Pairs

Raw Materials:

• 1x Plasma-cut aluminum plate set
• 1x 2x2x30in Aluminum Extrusion
• 1x 2x2 Aluminum Extrusion Right Angle Brace
• 2x Aluminum Extrusion Sliding Nut
• 1x 3D Printer Filament
• 400x 4-40 screws 5/16in
• 40x 4-40 washers & nuts
• 24x 6-32 screws 1/2in
• 24x 6-32 washers & nuts
• 16x 1/4-20 screws 1/2in
• 16x 1/4-20 washers & nuts
• 1x Magnetic Latch
• 2x Metal Hinge
• 4x Spray Paint Cans

The Multipurpose Mobile Manipulator Mark II is divided into three major assemblies: the base, chest, and arms. The base contains motors for mobility and batteries to power the robot. The arms contain grippers, shoulder and elbow joints and an extensible arm for interacting with environments. The chest connects all of these together with control electronics and serves as a platform for an intelligent laptop-for-a-face.

Plasma Cutting

To begin preparing for assembly, plasma cut all of the aluminum plates, bend them using a sheet metal bender at the necessary angles, and make sure all the pieces fit together. Due to the low tolerances of bending metal by hand, slight imperfections during metal bending might make some pieces very hard to fit. To account for this, use a drill to make screw holes larger until all pieces fit together as desired.

Drilling

Many steps of the assembly require screws to fasten two connecting aluminum plates. Many screw holes are intentionally made smaller than the diameter of the screw threads in order to account for the variable burn radius of the plasma cutter. Drill these until they are the correct size for the screws.

3D printing

Some components on the main robot assembly are designed to be 3D printed. Supports can be 3D printed and mounted on the robot at various locations for increased integrity. Additionally, the grippers on each of the robot's arms are adaptable to perform a variety different tasks, where each task has a very specialized set of 3D printable grippers. These are left for the user to design, experiment and iterate upon (a few examples have been provided).

Note: This project is not meant for beginners, and prior knowledge on how to use a variety of software, tools and equipment is required! The following instructions will assume some experience with mechanical assemblies, soldering, electronic layouts, current and voltage, schematics, scripting, hardware troubleshooting, rapid fabrication, Arduino, Python scripting and more. It is highly recommended to read all of the instructions before attempting to build in order to get a general idea of how everything is supposed to work together.

To begin constructing the base of the robot, prepare the red emergency stop.