Posts by Brandon
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We are rolling out another set of new products here at Pololu: Scooter/Skate Wheels. They are available in 144×29 mm, 100×24 mm, 84×24 mm, and 70×25 mm sizes, offering larger alternatives to our line of Pololu Wheels. They are compatible with standard 608 bearings, so they also work with our Aluminum Scooter Wheel Adapters, which make it easy to connect these wheels directly to an assortment of motors for use in robot drive systems:
You can find more information about these wheels on their product pages:
Helen Lawson designed and built a one-sixth scale Mark 1 British Heavy Tank replica that is a functional, radio controlled robot. The replica has been a work in progress for around three years and is now reaching completion. Helen designed the main chassis out of laser-cut wood and made other aspects of the chassis from aluminum and 3D printed parts.
One distinguishing feature of a MK 1 British Heavy Tank is the lack of a central turret. Instead, it has a sponson on each side. This proved challenging for Helen’s build since most electronics made for RC tanks only allow for a single gun and turret. To make the sponsons functional, Helen used a combination of an RC receiver, an RC switch with digital output, an RC switch with relay, a Micro Maestro servo controller, a few servos, and a Taigen gun flash unit. You can find more detailed information about this part of the system (including a wiring diagram and Maestro script) in her post on our forum. The images below show each side of one of the completed sponsons:
She also made a 3D-printed case for the Maestro (shown in the photo on the right) and a few of the other electronic components, which she made available on her Thingiverse page.
You can see a video of the robot in action on this Portsmouth Model Boat Display Team Armoured Division Facebook page, and even more information on her build, including many more pictures, in Helen’s forum thread at landships.net.
Before I started designing my entry into this year’s LVBots mini sumo competition, I watched several videos of other competitions. I noticed a majority of the victories came from engaging the opponent from the side or back; a pattern I also noticed during the last LVBots mini sumo competition. For that competition, I made a robot that used a blade and sensors on the front and back of the robot (basically making the robot have two fronts and no back). However, my strategy in that competition was to roam the ring and search for the opponent, which I suspect increased the chances of the opponent engaging from a suboptimal angle. This time, I wanted to try having my robot spin in place looking for the opponent and striking once it was found. This ultimately resulted in my newest mini sumo robot, Black Mamba. For those unfamiliar, a black mamba is a snake with a reputation for being highly aggressive and is one of the longest and fastest-moving snakes in the world. A black mamba’s venom is highly toxic, and it is capable of striking at considerable range, occasionally delivering a series of bites in rapid succession. Black Mamba is also Kobe Bryant’s self-appointed nickname (yes, I am a Lakers fan). Continued…
Jay Doscher posted on his blog at Polyideas.com about his 2-axis solar tracker designed to provide the optimal amount of power output with a portable setup. In the build, Jay uses a Raspberry Pi A+ topped with our Dual MC33926 Motor Driver for Raspberry Pi to control the motion of the system, which is accomplished using a Concentric 4″ linear actuator with feedback. In lieu of a GPS unit, the tracker uses hard-coded longitude and latitude coordinates with Pysolar, an open-source Python library, to calculate the sun’s predicted position. The system keeps the solar panel pointed at the calculated position with the help of a Razor IMU from SparkFun. The video above is time lapse footage of a mechanical test of the system that shows the unit tracking the sun (although it is indoors).
In the picture above, you can see the Raspberry Pi and dual MC33926 driver board on the left and the IMU on the right. The Dual MC33926 Driver for Raspberry Pi fits on top of the Raspberry Pi mainboard, eliminating a lot of wiring and making it easy to use while also leaving the setup looking clean and organized. Additionally, the Dual MC33926 Driver for Raspberry Pi provides a set of three through-holes where an appropriate voltage regulator can be conveniently connected, allowing the motor supply to also power the Raspberry Pi. You can see one of our D24V10F5 switching step-down regulators mounted on top of the dual MC33926 driver board to serve this purpose in the picture above as well.
This project was also a 2015 Hackaday Prize entry and made it to the quarterfinals!
For more information about this project, see Jay’s blog post, which has additional photos and details including a parts list and links to his code.
A contact at Mexican distributor Cosas de Ingeniería wrote to let us know about a contest he is helping organize in Juriquilla, Querétaro, Mexico. The Mexican Mechatronics Asociation (Asociación Mexicana de Mecatronica A.C.) will be hosting the 14th National Congress of Mechatronics (14º Congreso Nacional de Mecatrónica) 2nd Robotics Competition on October 15th through 17th this year. The three-day event will host several robotic competitions:
- Autonomous Vehicle Competition (based on the Sparkfun Autonomous Vehicle Competition)
- Insect Robot Race (insectoid robots try to be the first to travel 2 m over obstacles and uneven surfaces)
- Mini-Sumo Competition (autonomous robots, similar to the one pictured above and our Zumo robots, fight to stay in a designated area)
- Line Following Competition (autonomous robots follow a line-marked course as quickly as they can)
In September of last year, we started carrying our Breakout Board for microSD Card, which was the first board that I ever designed and routed here at Pololu. It is a simple breakout board that gives direct access to each contact available on a microSD card socket. However, since microSD cards operate at 3.3 V, it can be tricky interfacing them with a 5 V system. To address this, we made a new version with an integrated 3.3 V regulator and level shifters. Even with the extra components (and mounting holes, which the mechanical engineers at here Pololu are always pushing for), the board is still compact, measuring only 0.94″ × 0.9″, and it breaks out all of the contacts from a microSD card socket necessary to interface with the card through its SPI bus mode interface to a single 1×9 row of 0.1″-spaced pins. This allows easy use with breadboards, perfboards, or 0.1″ connectors.
You might recognize the circuit from our A-Star 32U4 Prime controllers, which use essentially the same level shifters to interface a microSD card with an Arduino-compatible ATmeg32U4 microcontroller running at 5 V.
For more information about this breakout board, see its product page.
For the recent LVBots line following competition, my first instinct was to try to come up with some unique alternative design for a robot that would be competitive with the traditional differential drive robots. However, I knew the winning robot from the last LVBots line following competition (Mostly Red Racer) would be returning, and it had an impressive time to beat. I also remembered spending so much time designing and assembling the hardware for my last line following robot, that I ended up not having enough time to tune the PID coefficients and get the performance I was hoping for. After brainstorming a few ideas, I ended up deciding to keep it simple and make sure I had enough time to get a robot I was happy with, which I ultimately named “The Chariot” because of its shape. The Chariot ended up winning second place in the competition, which I was very happy with. Instead of focusing this blog post on how you can make your own version of The Chariot, I will try to explain my thought process throughout the design and build process, In other words, my hope is that after reading through this post, it will be clear why I chose the parts that I did. Continued…
New products: Stepper motors with lead screws, traveling nut, and mounting bracket for NEMA 23 stepper motors
NEMA 17-size stepper motors with 18, 28, and 38cm lead screws.
Since we started carrying the stepper motor with 28cm lead screw, we have routinely received requests for shorter and longer versions of it, so we are happy to announce that we are now carrying two additional versions: one with an 18 cm lead screw and one with a 38 cm lead screw. All three of the stepper motors with lead screw use the same NEMA 17-size stepper motor, which is also available without a lead screw.
All of the stepper motors with lead screw come with a traveling nut, also known as a carriage nut. This copper alloy nut features a mounting flange with four holes threaded for M3 screws to make it easy to integrate into your project. From time to time, we also get requests to make the traveling nut available for purchase separately, so we did! If you are interested in picking up some spare traveling nuts, more information can be found on the traveling nut’s product page.
We also have a new NEMA 23 stepper motor bracket as pictured above. Around eight months ago, we started carrying our stamped aluminum mounting bracket for NEMA-17 size stepper motors, and since then, we added a stamped aluminum NEMA 14 stepper motor bracket to our selection. We looked into getting similar aluminum bracket for NEMA 23-size stepper motors but ultimately decided to go with a more rigid 3mm-thick steel mounting bracket for NEMA 23 stepper motors. On this bracket, two steel supports are welded in the corner along the bend of the bracket to provide extra reinforcement.
Bruno Schneider posted the above video on our forum that showcases an automated ball path machine he made for last year’s advent season with his brother and father. The contraption uses a 24-channel Mini Maestro and is displayed in the window of his mother’s sewing shop. The machine is fun and impressive by itself, but the video (with accompanying sound effects) makes the project even more entertaining.
If you make or have made any festive projects using the Maestro or any of our other products, we would love to see them! You can post them in the comments below or in the Share Your Projects section of our forum, which is also a great place to browse for inspiration or ideas for a new project.
The people at Seewald Solutions posted about their Raspberry Pi-based robot they call ToyCollect. Inspired by the creator’s daughter, who hides her toys under the couch, the robot is controlled via Android and can be driven under the couch to allow the user to view the hidden toys via a Raspberry Pi camera module and retrieve them. Along with a Raspberry Pi, the ToyCollect robot uses a Zumo Chassis Kit, 100:1 Micro Metal Gearmotors HP, Qik 2sv1 Dual Serial Motor Controller, and a Zumo blade to push the toys. The video below shows the robot in action (in German; subtitles available):
For more information, including the source code and instructions for building your own ToyCollect robot, see the ToyCollect post on the Seewald Solutions website.