Introduction: Build a Waldo for Arduino Robot Arms

About: At LittleBots we are creating 3D Printed Robot Kits that get Kids excited about robotics and STEM

This is a tutorial about how to make a Waldo for small Arduino robot arms, specifically the LittleArm. A Waldo is a means of capturing motion data to use in a robot, or an animation.

This Waldo and the code around it is specifically designed for the LittleArm, but is can work with other arduino robot arms as well.

Step 1: What Is a Waldo/Telemetry Suit

A Waldo is a means of capturing motion data. Waldos were originally developed within the film industry in order to control robotic or animated character. Here is a video of variation of a Waldo, called a telemetry suit, used to control the robot Johnny 5 on the movie Short Cicuit. Telemetry is the “the process of recording and transmitting the readings of an instrument,” which is just what a Waldo does.

The name “Waldo” comes from a short story where an engineer named Waldo Farthingwaite-Jones creates a set of gloves that control a large mechanical set of hands. The name Waldo was later trademarked to mean, “data-capture input devices.”

In the most basic sense a Waldo is a device that is used to control articulated robots by having them mimic the motion of the Waldo. The Waldo for the LittleArm arduino robot is no different.

The way that the the LittleArm Waldo works. It collects data on the position of the Waldo and then that data is sent to the arm so the LittleArm can match the position of the Waldo.

The way the the LittleArm Waldo collects that data is though potentiameters. Potentiameters are variable resistor which you can use to generate an angle of rotation. Video below for more details on potentiometers. The angle of the potentiameter can be determined by reading the resistor value (range 0-1023) and then converting that into an angle from 0-180.

Step 2: Parts

Here is the list of parts that you will need to make the Waldo. 3D printed components can be downloaded from here. The files are names either Waldo#.# or training_arm#.#.

They take appoximately 3-4 hours to print at .3 mm layer height. If the files are not clearly scaled in the software then scale them 10x.

Step 3: Cut and Splice Power Wires the Wires

Start with the black and red power wires.

  1. Join them in the lengths that will allow it to fit on the 3D printed parts of the Waldo.
  2. Apply solder to the spliced areas of the wire.
  3. Apply solder to the two outer pins of the Potentiometers. Note: Do not ally solder all the way to the circular depression on the pin. This can cause a failure of the Poteniometer.
  4. Solder the prepared wires to the prepared pins, according to the wiring diagram.

Step 4: Apply the Signal Wires

Repeat the preparation steps for soldering on the center pins and all signal wires. Then connect the signal wires to the center pins according the wiring diagram.

Step 5: Connect Switch

Connect the SPST push-button switch to the ends of the remaining wires. Ensure the that the 10K resistor is attach according to the wiring diagram between the switch and the potentiometer ground signal.

Step 6: Attach Switch

Hot glue the switch the the end of the Waldo Arm and cover in 10mm heat shrink tubing.

Step 7: Mount Potentiometers

Using pliers remove the standoff's from the from of all the potentiometers and insert into their respective locations in the Waldo and secure with their accompanying nuts. Do not mount the parts to the potentiometer spindles yet.

Step 8: Connect to Arduino or Meped Board

If you are using an Arduino Uno you will have to edit the code in order to change the pins that the potentiometers send signals to. Else, connect female pin headers to the each wire end (solder if they need to be secured better) and insert into header cover according to the photograph. Then connect to the Meped Board according to the image and schematic.

Step 9: Flash Arduino

Download the Waldo code (Waldo_V#.#) from the LittleArm website and upload to the Arduino Nano using the Arudino IDE.

Step 10: Calibrate

Connect power and turn on the board. Each potentiometer should control a servo on the arm. If not check you connections and ensure that no wires are crossed.

If all is working well rotate the potentiometers of each joint and then mount them to the 3D printed Waldo pieces, so that the Waldo matches the position of the LittleArm.

When complete the LittleArm should match the motion of the Waldo just like a shadow.

Step 11: Expansions

Now you have a Waldo. If you would like to expand upon that then just create a script that records the position of the servos as the Waldo is moved and then plays those back when a button is pressed. A demo of this is shown above.

Enjoy your Waldo.