3D Print and Program This Cute Bipedal Arduino Bot

Bipedal robots aren’t always easy to build (this one is) but they’re so human! I built my first humanoid robot when I was 8. It rolled on training wheels, with pseudo-circuits built from HVAC foil tape and old cassette deck switches. A now-infamous robot claw pincher arm shook people’s hands — and sometimes gave them a mild shock from a step-up transformer inside. Thankfully, I did get nicer as I grew up.

As a DIY robotics hobbyist I developed open source robots like Eddie the balance bot and made contributions to some of Trossen Robotics’ more advanced humanoids, the HR-OS1 and HR-OS5. Now I’ve begun working with Trossen and its subsidiaries Interbotix Labs and RobotGeek, doing what I love: making robots do amazing things. One of my newest designs is a robot that I think is quite adorable: Chip-E.

Chip-E started as a personal project to cheer me up during a rough time due to the loss of a family member. Having a supply of RobotGeek components on hand, I thought about a simple bipedal design, but having built some of the other 4-servo bipeds out there, I wanted to do something different.

Chip-E has an LCD for “eyes” enabling visual feedback, a piezoelectric buzzer for auditory feedback, and an IR sensor for control. These features are complemented by 4 strong RGS-13 servos and the ability to add more sensors. Like his sibling Eddie, Chip-E is designed to be easy to 3D print and to bring joy to those who appreciate him. (Many makers may recognize the symbolism of the “dot” and notched corner, giving him the look of a microchip.)

Bots Made for Walking

Bipedal robots come in many configurations. Some are simplified and focused on efficiency while others can be complex and challenging to balance. The movement pattern of the legs to produce locomotion is known as the gait. In a robot like Chip-E, gait generation is simplified to an oscillation of the servo positions to produce different patterns of movement. Chip-E’s large footprint and high servo torque provide definite balancing advantages to this design.

We at Trossen have made the RobotGeek Chip-E robot our first 3D-printable kit: You print the body and we provide all the components in a handy kit. Included is our new universal IR game-pad for wireless control, with lots of buttons for performing actions or changing settings; its dual mode even lets you control 2 robots. Chip-E’s code is based on the Zowi project and is compatible with BoB, Otto, and other open source bipeds.

Having 2 legs means Chip-E can walk, dance, or even shuffle his way around your workspace or play area. And because he’s small and tough, he’s ready to come along on an adventure and see the world.

Building Your Chip-E

Complete instructions are available over at RobotGeek. Here’s an overview.

1. Set up the Geekduino

Download Chip-E’s code and the necessary libraries to your computer from GitHub, then open the code in the Arduino IDE and upload it to the Geekduino board. Stack the Sensor Shield on top.

2. Prep the servos

The servos are your robot’s hip and foot joints, so you need to set them to a specific position before assembling your robot or it won’t work correctly. To center your servos at 90°, plug them into Sensor Shield’s digital I/O pins 3, 5, 6, and 9, then run the Arduino sketch centerServo.ino. Now you can install the servo horns.

3. Assemble your robot

Bolt Chip-E together (Figure A) following the RobotGeek assembly guide.

4. Connect the electronics

Connect the servos, LCD, buzzer, and IR receiver to the Sensor Shield as follows, and you’re done (Figure B).

Right Hip Servo	Digital 9
Left Hip Servo	Digital 10
Right Foot Servo	Digital 5
Left Foot Servo	Digital 6
LCD Screen	I2C
Buzzer	Digital 12
IR Receiver	Digital 2

5. Program and control Chip-E

Upload and run the Chip-E_Gamepad demonstration sketch and start moving Chip-E with the IR game pad (Figure C):
» Directional Pad: Walk forward or back, and turn left or right.
» TA and TB buttons: Speed up and slow down Chip-E’s walking gait.
» A, B, Select, and Start buttons: Chip-E is very excitable; make him wiggle in place or dance!
» A/B switch: Switch between 2 signal modes to run 2 robots, or to avoid crosstalk from another IR device.

6. Tune your Chip-E

If you notice Chip-E’s legs are a bit off center and his feet aren’t exactly parallel to the ground, you can fix this easily in code by adjusting a few values in lines 72–75 in the Chip-E_Gamepad sketch:
const int TRIM_RR = -5; //Trim on the right ankle
const int TRIM_RL = -7; //Trim on the left ankle
const int TRIM_YR = -4; //Trim on the right hip
const int TRIM_YL = -2; //Trim on the left hip

These values can be changed to any whole number, positive or negative, to adjust the center position of each servo. You can start by setting them all to zero, loading the code, and observing the default positions.

Customizing Your Biped

Chip-E’s got room for more RobotGeek modules such as temperature and light sensors, IR transmitters, and LED lights. Customize the Arduino code to enable functionality unique to your liking. Print him in any colors you like, or download the Sketchup file and totally redesign him.

Woohoo! I hope everyone else likes these as much we do.