Pololu Balboa 32U4 Balancing Robot Kit (No Motors or Wheels)

The Balboa 32U4 is a small, user-programmable balancing robot based on the Arduino-compatible ATmega32U4 AVR microcontroller from Microchip (formerly Atmel) and featuring two H-bridge motor drivers, quadrature encoders for closed-loop motor control, a full inertial measurement unit (3-axis accelerometer, gyro, and magnetometer) for estimating orientation and balancing, and an optional interface for connecting a Raspberry Pi to make a Raspberry Pi-controlled balancing robot. The control board includes a powerful 5 V switching step-down regulator that can supply up to 2 A continuously, along with a versatile power-switching and distribution circuit. Three on-board pushbuttons offer a convenient interface for user input, while indicator LEDs, a buzzer, and a connector for an optional LCD (not included) allow the robot to provide feedback.

This is a kit; assembly (including soldering) is required. Motors and wheels are not included so you can choose your own to personalize your robot; see below for details. Balboa runs on six AA batteries (not included), and a USB A to Micro-B cable (not included) is required for programming.

Like Pololu's Zumo 32U4 robot and A-Star 32U4 programmable controllers, which are based on the same microcontroller, Balboa 32U4 features a USB interface and ships preloaded with an Arduino-compatible bootloader. A software add-on is available that makes it easy to program the robot from the Arduino environment, and Pololu have Arduino libraries and example sketches to help get you started. A USB A to Micro-B cable (not included) is required for programming. For those who want to customize or enhance their robots with additional peripherals, the robot’s power rails and microcontroller’s I/O lines can be accessed via 0.1"-spaced through-holes along the sides, front/top, and back/bottom of the control board.

The Balboa 32U4 control board can serve as the robot’s main controller, or it can act a base for a more powerful Raspberry Pi controller. With the addition of a 2×20 female header and standoffs (neither of which are included), a compatible Raspberry Pi (Model B+ or newer, including Pi 3 Model B+ and Model A+) can plug directly into the board. Integrated level shifters make it easy to set up I²C communication and interface other signals between the two controllers, and the control board automatically supplies 5 V power to an attached Raspberry Pi. In this setup, the Raspberry Pi can handle the high-level robot control while relying on the Balboa’s ATmega32U4 microcontroller for low-level tasks, like running motors, reading encoders, and interfacing with other analog or timing-sensitive devices.

Balboa 32U4 Balancing Robot with 80×10mm wheels and a Raspberry Pi 1 Model A+.

Balboa 32U4 Balancing Robot with 80×10mm wheels and a Raspberry Pi 3 Model B.

Balboa 32U4 Balancing Robot with 80×10mm wheels and a Raspberry Pi Zero W.

For those who want to operate the Balboa as a traditional differential-drive robot oriented on its side, a Stability Conversion Kit is available separately. This accessory snaps onto the front end of the Balboa chassis to make it longer and holds an included ball caster, providing a low-friction third contact point. This add-on is also useful in balancing applications, where the ball caster can be left off and the extension piece can be used to make the Balboa taller and give it more mounting points. For those who want to supply their own electronics, see the Balboa Chassis with Stability Conversion Kit.

Stability Conversion Kit for Balboa, bottom view.

Balboa Chassis with Stability Conversion Kit and 80×10mm Pololu Wheels.

One of the many possible configurations of the bumper cage on the Balboa 32U4 Balancing Robot (lengthened with Stability Conversion accessory).

The 5-Channel Reflectance Sensor Array for Balboa can mount directly to the Balboa 32U4 control board and provides an easy way to add line sensing to a balancing Balboa.

5-Channel reflectance sensor array for Balboa in the edge-aligned mounting option.

Selecting motors and wheels

A look inside the external gearbox on the Balboa 32U4 Balancing Robot.

The Balboa uses two micro metal gearmotors to drive external 2-gear gearboxes that further increase the gear ratio and support the weight of the robot with ball bearings rather than the motor shafts themselves. The Balboa kit gives you five reduction options to choose from when assembling your robot (ranging from 1.64:1 to 2.88:1), and you can further customize the gear ratio based on which micro metal gearmotor you choose for your robot, which is why Pololu do not include motors with the kit. The integrated quadrature encoders require gearmotors with extended motor shafts, and Pololu specifically recommend the 30:1 HPCB, 50:1 HPCB, or 75:1 HPCB versions.

Pololu also do not include wheels with the kit since there are a number of options to choose from. Pololu recommend 80×10mm Pololu wheels, which are available in five colors — black, red, yellow, blue, and white — but Pololu's larger 90×10mm wheels and smaller 70×8mm wheels are also options if you know what you are doing (note that the 70×8mm wheels only offer a few millimeters of clearance when balancing).

Balboa 32U4 Balancing Robot with 70×8mm wheels.

Balboa 32U4 Balancing Robot with 80×10mm wheels.

Balboa 32U4 Balancing Robot with 90×10mm wheels.

Kit contents

With the exception of motors and wheels, this kit contains everything necessary to build a Balboa 32U4 balancing robot:

Balboa 32U4 Balancing Robot Kit components (wheels and motors are not included).

All units sold after 19 May 2017 also include a bumper cage kit that can optionally be used to protect the robot from falls or as skids that the Balboa can rest on while driving around as an alternative to balancing:

Bumper Cage Kit for Balboa 32U4 Balancing Robot.

One of the many possible configurations of the bumper cage on the Balboa 32U4 Balancing Robot.

One of the many possible configurations of the bumper cage on the Balboa 32U4 Balancing Robot.

The Balboa 32U4 can drive around on its side while resting on the bumper cage skids.

See the Balboa 32U4 balancing robot user’s guide for detailed assembly instructions.

Dimensions

Dimensions of the Balboa 32U4 Balancing Robot with 80×10mm wheels.

Protecting against falls

When you are using the Balboa as a balancing robot, it is important to protect the electronics from hard falls that could damage them. In general, Pololu recommend running the Balboa on soft surfaces, such as carpet, and it helps to install the included bumper cage so that there is something to hit the ground before the electronics (see the pictures in the “Kit contents” section above). You can also make your own protective bumpers if you want, and the pictures below show two such home-made examples:

Balboa 32U4 Balancing Robot with 80×10mm wheels and 3D-printed arms.

Balboa 32U4 Balancing Robot with 80×10mm wheels and arms made from LEGO blocks.

Pololu have made the arms in the left picture available on Thingiverse so those with access to 3D printers can print their own.

People often buy this product together with:

Pololu Wheel 80×10mm Pair - Black

Pololu Wheel 80×10mm Pair - Red

Pololu Wheel 80×10mm Pair - Blue

Dimensions

Notes:

1

Of assembled robot with 80×10 mm wheels (not including bumper cage, which can be installed in a variety of orientations).

2

Of assembled robot as shown in the main product picture, with motors, 80×10 mm wheels, and bumper cage. This weight does not include batteries.

Documentation and other information

• 

  Pololu Balboa 32U4 Balancing Robot User’s Guide (Printable PDF)

  User’s manual for the Pololu Balboa 32U4 balancing robot.

File downloads

• Pololu A-Star 32U4 drivers for Windows (version 1.3.0.0) (7k zip)

  This download contains the Windows drivers for the A-Star 32U4 and the rest of Pololu's 32U4 family of boards.

• Schematic diagram of the Balboa 32U4 control board (587k pdf)

• Pinout and power distribution diagrams of the Balboa 32U4 control board (2MB pdf)

• Gear ratio chart for the Balboa Chassis (447k pdf)

  This printable 1:1 scale chart helps you identify the gears included in the Balboa 32U4 Robot Kit and Balboa Chassis Kit and details the available gear ratios.

• Dimension diagram of the Balboa 32U4 Control Board (471k pdf)

• Dimension diagram for the Balboa 32U4 Balancing Robot Kit (734k pdf)

• Dimension diagram of the Bumper Cage Kit for Balboa 32U4 Balancing Robot (152k pdf)

• Balboa Bumper Cage assembly reference diagram (2MB pdf)

  Note: all angles shown assume the use of 80mm wheels.

• 3D model of the assembled Balboa Balancing Robot (24MB step)

  Note: this model includes micro metal gearmotors and 80mm wheels that are sold separately from the Balboa 32U4 Balancing Robot Kit. This model uses a simplified model of the Balboa 32U4 Control Board to reduce the file size.

• 3D model of the Balboa 32U4 Control Board (27MB step)

  Note: this model includes an LCD and headers that are sold separately from the Balboa 32U4 Balancing Robot Kit.

• Drill guide for the Balboa 32U4 Control Board (285k dxf)

  This DXF drawing shows the locations of all of the board’s holes.

• LSM6DS33 datasheet (1MB pdf)

  Datasheet for the ST LSM6DS33 3D accelerometer and 3D gyroscope.

• LIS3MDL datasheet (2MB pdf)

  Datasheet for the ST LIS3MDL 3-axis magnetometer.

Recommended links

• Balboa 32U4 Arduino library

  The Balboa32U4 library for the Arduino IDE helps interface with the on-board hardware on the Balboa 32U4 control board as well as the optional 5-channel reflectance sensor array for the Balboa.

• Balboa 32U4 library documentation

• LSM6 library for Arduino

  An Arduino library for interfacing with the LSM6DSO and LSM6DS33 accelerometer and gyro ICs.

• LIS3MDL library for Arduino

  An Arduino library for interfacing with the LIS3MDL magnetometer.

• Forum post: Correcting the Balboa magnetometer

  Pololu forum user Jim Remington has shared a technique for compensating for hard iron distortion of the Balboa’s magnetometer. After corrections, he was able to create a compass program with a basic accuracy of ±2°, sufficient for navigating the Balboa around the room.

• Arduino Software

  Arduino integrated development environment (IDE) software

• minimu9-ahrs software for Raspberry Pi

  This is a program for reading sensor data from Pololu IMU boards over I²C. It was written for and tested on the Raspberry Pi, but it will probably also work on similar embedded Linux boards that support I²C.

• Beefy arms for Balboa

  These 3D-printable support arms for the Balboa robot are a fun add-on that can help protect the robot’s electronics from damage if it falls over or runs into an obstacle.

• A-Star repository on GitHub

  This repository contains Arduino add-on files, Windows drivers, and bootloaders for the A-Star 328PB, A-Star 32U4, and the rest of Pololu's 32U4 family of boards.

• ATmega32U4 documentation

  Microchip’s product page for the ATmega32U4 AVR microcontroller, with links to its datasheet, application notes, and other resources.