The Pololu Zumo 32U4 robot is a versatile tracked robot based on the Arduino-compatible ATmega32U4 MCU. It includes microcontroller, motor drivers, LCD, encoders, line sensors, proximity sensors and a full IMU for detecting impacts and tracking orientation and acceleration in three dimensions.
The Zumo 32U4 is a highly integrated, user-programmable and customisable tracked robot. It measures less than 10 cm on each side and weighs approximately 275 g with batteries (170 g without), so it is both small enough and light enough to qualify for Mini-Sumo competitions, but its versatility makes it capable of much more than just robot sumo battles.
At the heart of the Zumo 32U4 is an Atmel ATmega32U4 AVR microcontroller, and like Pololu's A-Star 32U4 programmable controllers, the Zumo 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 we have Arduino libraries and example sketches to help get you started. A USB A to Micro-B cable (mobile phone size is not included) is required for programming. For advanced users 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 and front of the main board.
|
Assembled Zumo 32U4 robot, front view |
Assembled Zumo 32U4 robot, side view |
Assembled Zumo 32U4 robot, back view |
The Zumo 32U4 features two H-bridge motor drivers and a variety of integrated sensors, including a pair of quadrature encoders for closed-loop motor control, a complete inertial measurement unit (3-axis accelerometer, gyro, and magnetometer), five downwards-facing reflectance sensors for line-following or edge-detection, and front- and side-facing proximity sensors for obstacle detection and ranging. Three on-board pushbuttons offer a convenient interface for user input, and an LCD, buzzer, and indicator LEDs allow the robot to provide feedback.
Main features of the Zumo 32U4 robot
This version of the Zumo 32U4 robot (item #3126) ships fully assembled with a pair of 75:1 HP micro metal gearmotors (with extended motor shafts).
You can use the following table to compare these gear ratios in more detail. The first four columns are specifications of the motors themselves, while the last column is the measured top speed of a Zumo chassis loaded to a weight of 500 g and driven with these motors. Note that the specifications are for 6V operation, which is approximately the voltage you would get with four alkaline batteries; four NiMH AA cells will typically provide less than 5V.
| Micro Metal Gearmotor | Free-Run Speed @ 6V | Stall Torque @ 6V | Stall Current @ 6V | Top Zumo Speed @ 6V and 500g | |
|---|---|---|---|---|---|
| 50:1 HP or 50:1 HPCB | 625 RPM | 15 oz·in | 1600 mA | 40 in/s | (100 cm/s) |
| 75:1 HP or 75:1 HPCB | 400 RPM | 22 oz·in | 1600 mA | 25 in/s | (65 cm/s) |
| 100:1 HP or 100:1 HPCB | 320 RPM | 30 oz·in | 1600 mA | 20 in/s | (50 cm/s) |
Pololu Zumo chassis kit, assembled bottom view with battery holder cover removed
The Zumo 32U4 robot runs off of four AA batteries. It works with both alkaline and NiMH batteries, though Polou recommend using rechargeable AA NiMH cells.
Polou's older Zumo robot for Arduino, built with a Zumo Shield, is another Arduino-compatible robotic platform based on the Zumo chassis. The Zumo Shield mounts to the Zumo chassis and features motor drivers and various sensors, but it does not have an integrated microcontroller; rather, it is designed to interface with boards that have a standard Arduino form factor, like an Arduino Uno, Arduino Leonardo, or A-Star 32U4 Prime, and these boards serve as the main controller for the robot.
A Zumo 32U4 robot (left) and a Zumo robot for Arduino with an A-Star 32U4 Prime LV (right)
By contrast, the Zumo 32U4 includes an on-board ATmega32U4 microcontroller (the same one used in the Leonardo and A-Star 32U4 boards), combining the functions of the Zumo Shield and the separate Arduino controller into a single, compact board that is just as easy to program as a standard Arduino or A-Star thanks to its USB interface and preloaded Arduino-compatible bootloader. The Zumo 32U4 retains all the features of the Zumo shield (e.g. dual motor drivers, inertial sensors, and buzzer) while adding many new features, including dual quadrature encoders, proximity sensors, an LCD, and two extra user pushbuttons.
Some of the pin mappings and software libraries differ between the Zumo 32U4 and Zumo robot for Arduino, so programs written for one robot generally need to be modified to work on the other.
| Version: | assembled with 75:1 HP motors |
|---|
Polou have noticed that the accelerometer in the LSM303D is particularly sensitive to brown-out conditions. If power is removed and the voltage on the 3.3 V power supply line falls significantly, but is not allowed to drop completely to 0 V, the accelerometer can be put into a bad state. When power is reapplied to the LSM303D, the accelerometer then returns readings on some or all axes that are large values and do not change much or at all. (Polou have often seen readings like -32760 and 24539.)
To prevent this problem from occurring, the voltage on the 3.3 V line must be allowed to fall to about 0 V when power is removed from the LSM303D. Depending on other loads and the amount of capacitance on the 3.3 V line, it can take up to several seconds for this to happen, meaning that you should avoid interrupting power to the LSM303D for any shorter period, and if such a short interruption does occur, you should remove power again for a longer period to allow the accelerometer to reset properly.
If the voltage takes too long to fall, you can add a resistor between 3.3 V and ground (a “bleeder resistor”) to discharge the 3.3 V line more quickly when power is removed. Polou suggest trying a resistor in the 1 kΩ to 10 kΩ range. (Note that a stronger bleeder resistor will cause the voltage to fall more quickly when power is removed, but it will also waste more power when the supply is present.)
The Zumo 32U4 includes a bleeder resistor on the 3.3 V line.
Brands
