Introduction: MR.D - Mobile Robotic Drummer

About: Composer, musical robot maker, educator, semi-nomadic robot herder.

This Instructable details assembly and getting started with the kit version of MR.D - the Mobile Robotic Drummer.

MR.D (Mobile Robotic Drummer, aka “Sparky” the InSoc robot) is an Arduino-based, expandable, hackable musical robot. This energetic little re-programmable robot features an endearing appearance, DC gear motor driven wheels, two servo driven striking arms, a distance sensor, buttons, and a multi-color LED indicator light. MR.D makes a great first robotics project for those who like to groove, and is a fun and effective STEAM education toy.

Out of the box, it can play rhythmic patterns on the floor, walls, and any objects placed in its patch, move around avoiding objects, navigate sonic obstacle courses, entertaining children, pets, and adults alike. With an Arduino Nano at its core, it can be easily reprogrammed via USB connection to your PC, Mac, or Linux computer. Drawing from a wealth of freely available online code examples from the global Arduino community, users can creatively expand the mobile drumming robot’s capabilities. MR.D’s custom printed circuit board has slots for microphone inputs, speaker output, wireless control board (for control via joystick and/or MIDI from your favorite software such as Ableton Live, Logic, Max, PD, GarageBand, etc.), additional sensors, and more, which may be available soon as expansion packs.

This robot was originally commissioned by the band Information Society for the release of their 2016 album Orders of Magnitude. During ideation discussions with vocalist/song writer Kurt Larson, a mutual admiration for Frits Lyneborg's "Little Yellow Drumming Machine" was identified, and the idea to produce a run of 100 robots based on a simplified version of this concept was launched.

Given the need to produce dozens of these robots in a short amount of time and on a tight budget in my little basement lab, CAD and custom PCB design software, as well as 3D printing and laser engraving at my local maker space were utilized in the creation of this robot.

Since that initial production run, MR.D, and its stationary variant, DR.D, have been used by dozens as a fun introduction to electronics, robotics, coding with the Arduino platform, algorithmic music, and more. Such introductions often occur in workshops for students of all ages (I've conducted these throughout the US and Europe, and hope to do so in more places soon). For current kit options, take a look at my Etsy shop. If you're interested in hosting or booking a musical robotics workshop/performance/talk, get in touch!

This Instructable is currently a work-in-progress and is geared toward those who have purchased a MR.D kit or DR.D->MR.D upgrade kit. Please post any questions in the comments. When I get a chance, I plan to post fabrication files and code for those who want to source, 3D print, and/or laser cut their own parts. If this is of interest to you, please let me know in the comments!

Step 1: Gather Parts and Tools

All required parts should be included with your kit (as shown in images).

Gather the following tools:

  • Phillips and slotted screwdrivers. A multi-bit tool or set will suffice for most of the screws, along with a small slotted screwdriver for the wiring screw terminals.
  • nut driver, small wrench, or pliers to tighten nuts for swivel caster
  • small needle nose pliers to assist with wiring (optional but helpful)

No soldering required for standard kit assembly.

Step 2: Prepare Chassis Base and Top

First peel the adhesive masking off both sides of the acrylic chassis top. The upward facing (matte) side will have multiple pieces of various shapes sizes left by the process of laser etching the top graphic. Scrape and peel all of these away with your fingernail or something soft (don't use metal tools or you'll most likely scratch the surface).

Press 8 of the black nylon M3 screws into the chassis top and bottom as shown, 4 in each, being careful to observe proper hole placement. You're pressing the top screws down into the chassis top from the top side (the matte side of the acrylic), and the base screws up from the bottom (textured side) of the black ABS chassis base.

Once the top and bottom are populated with parts and wired together in subsequent assembly steps, these screws will be used to connect the base and top using standoffs in a later step.

Step 3: Affix the Swivel Caster to the Chassis Base

Use a nut driver, a hex key, wrench, or pliers to tighten the flathead screws + locknuts to firmly hold the caster in place as shown. Make them hand-tight (but not so tight that they flex the base).

Step 4: Mount the Battery Holder

Using the two 6-32 panhead locking screws, affix the battery holder to the base as shown.

Step 5: Attach the L298N Dual Motor Controller Module to the Base

Using four of the 4-40 screws, fasten the motor controller to the base as shown.

Step 6: Fasten the HC-SR04 Ultrasonic Distance Sensor to the Base

Using two of the 4-40 screws, attach the distance sensor to the base as shown.

Step 7: Attach the Left and Right Striking Arms

Observing the handedness of the striking arms, attach left and right striking assembly to the base as shown, using two 4-40 screws for each arm.

Step 8: Screw the Standoffs Onto the Chassis Base

Step 9: Mount the Left and Right Drive Motor Assemblies to the Base

Step 10: Wire the Drive Motors to the L298N Motor Controller

Step 11: Insert the Arduino Nano Into the PCB and Affix Assembled Board to Chassis Top

Step 12: Construct the RGB LED Assembly

Step 13: Affix and Wire the LED Assembly to the Chassis Top and Insert Power Switch

Step 14: Wire the Power Connections

Step 15: Wire the Striking Arm Servos to the PCB

Step 16: Connect the 10-conductor Rainbow Wire Harness From Custom PCB to L298N and HC-SR04

Step 17: Complete Assembly, Program Your MR.D, Test, and Play!

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