Author Archives: Ryan

Semi-autonomous 14-DOF quadrupeds using Mini Maestro

via Pololu Blog

Customer Lujing Cen’s team built two semi-autonomous 14-DOF quadrupeds using Mini Maestros for their high school class project at the California Academy of Mathematics and Science. The project syllabus includes making two separate robot designs and three total robots that work together. These quadrupeds were the “pack robots” described in the syllabus. An 18-channel Mini Maestro USB servo controller controls the twelve leg and two head servos. The project code includes a rewrite of Pololu’s Maestro C# USB SDK library in Python. The robot uses a camera and an RFID scanner to track its targets.

For the complete project documentation including more pictures and videos, see their GitHub project page. Lujing also posted about it on the Pololu Forum.

FEETECH High-Torque Servo FS5115M

via Pololu Blog

We added the FEETECH High-Torque Servo FS5115M to our expanding RC servo selection. This standard-size analog servo has a stall torque of 215 oz-in (15.5 kg-cm) at 6 V, more than twice the torque of our standard-size servos with plastic gears thanks to its powerful motor and all-metal gear train. This higher torque requires more power: this servo can draw bursts of current in excess of 3 A at 6 V, about three times higher than a typical standard-size servo. The output shaft is supported by two ball bearings for reduced friction.

Comparison to the Power HD 1501MG high-torque servo

This servo is a lower-cost alternative to the 1501MG from Power HD, which has nearly identical dimensions and similar performance. The two servos should be generally interchangeable for most applications. The picture below shows both the FS5115M and the 1501MG side by side:

Expect more new FEETECH servos in the coming weeks!

Line-following robot and mini-sumo main board from tdrobótica.co

via Pololu Blog

One of our distributors in Colombia, tdrobótica.co, has developed a line-following robot kit and a mini-sumo main board kit.

The first kit includes everything you need to build a sleek line-following robot. It uses an Arduino-compatible A-Star 32U4 Micro as the main controller. It also uses a DRV8833 Dual Motor Driver Carrier, two Pololu micro metal gearmotors, brackets, and a 3/8″ ball caster.

The second kit is also based on the A-Star 32U4 Micro and DRV8833 carrier, and it includes much of the electronics needed to build a custom mini-sumo robot, including a buzzer, a voltage regulator, and an IR receiver for controlling it with a TV remote. It has two DRV8833 carriers, each with their channels paralleled to drive a total of two motors. There are connection points for 7 digital sensors (up to 5 can be analog).

tdrobótica.co’s mini-sumo main board kit.

For more information (in Spanish), see the line-following robot kit and a mini-sumo main board product pages.

FEETECH Ultra-High-Torque, High-Voltage Digital Giant Servo FT5335M

via Pololu Blog

We added the FEETECH Ultra-High-Torque, High-Voltage Digital Giant Servo FT5335M to our expanding RC servo selection. This giant-scale digital servo can deliver twice the torque of our strongest standard-size servo, offering up to 550 oz-in at 7.4V or 480 oz-in at 6 V. This torque requires significant power: the FT5335M can draw bursts of current over 9 A at 7.4 V, and unlike typical hobby servos, has an operating voltage range of 6 V to 7.4 V.

FEETECH Ultra-High-Torque, High-Voltage Digital Giant Servo FT5335M compared to a standard-size servo.

The FEETECH Ultra-High-Torque, High-Voltage Digital Giant Servo FT5335M has an all-metal gear train.

This servo is a lower-cost alternative to the very similar 1235MG from Power HD. The two servos are approximately the same size, though the mounting hole spacing differs between the two, and they have almost identical performance specifications. The output shaft of the 1235MG is supported by two ball bearings while the output shaft of the FT5335M is supported by bushings. The picture below shows both the FT5335M and the 1235MG side-by-side:

Expect more new FEETECH servos in the coming weeks!

Aluminum standoff for Raspberry Pi

via Pololu Blog

We are now carrying the Aluminum Standoff for Raspberry Pi: 11mm Length, 4mm M2.5 Thread, M-F. The 11 mm body length is just right for mounting expansion PCBs or HATs with standard-size female headers on a Raspberry Pi. The male M2.5 threads extend another 4 mm past the standoff body, and the female M2.5 threads extend at least 6.35 mm into the body. We carry M2.5 nuts and 6 mm M2.5 screws separately.

Two of these standoffs are needed to mount a Raspberry Pi on a Balboa 32U4 robot:

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

We also carry a 11 mm standoff with longer, 6mm threads. (We do not recommend these for the Balboa because the threads hit the robot chassis.)

Romi and Raspberry Pi robot

via Pololu Blog

Forum user DrGFreeman has been busy making robots. I wrote earlier about his Custom Mini Sumo robot; now here is his Romi Chassis and Raspberry Pi robot. It solves mazes using a webcam to do line tracking and intersection identification. This robot is a great example of how a variety of Pololu robot parts can combine into an attractive and functional robot. A black Romi chassis kit provides the base for the robot, to which DrGFreeman added a encoder pair kit and ball caster kit. An A-Star 32U4 Robot Controller SV with Raspberry Pi Bridge drives the motors and monitors four Sharp GP2Y0A60SZLF analog distance sensors and the Romi encoders. The robot controller and the Raspberry Pi communicate via I²C and are elevated above the chassis on a narrow Pololu RP5/Rover 5 expansion plate.

DrGFreeman is also working on a mast for three VL53L0X time-of-flight distance sensor carriers that he plans to add for simultaneous localization and mapping (SLAM).

For more videos, pictures, and details, see the forum thread. The robot’s Raspberry Pi (Python) and Arduino code is available on GitHub.