Adding Position Control To An Open Source Brushless Motor Driver

Brushless motors are everywhere now. From RC planes to CNC machines, if you need a lot of power to spin something really fast, you’re probably going to use a brushless motor. A brushless motor requires a motor controller, and for most of us, this means cheap Electronic Speed Controllers (ESC) from a warehouse in China. [Ben] had a better idea: build his own ESC. He’s been working on this project for a while, and he’s polishing the design to implement a very cool feature – position control.

We’ve seen [Ben]’s work on his custom, homebrew ESC before. It is, by any measure, a work of art. It’s capable of driving brushless and brushed motors with a powerful STM32F4 microcontroller running ChibiOS that’s able to communicate with other microcontrollers through I2C, UART, and CAN bus. If you want to build anything with a motor – from a CNC machine to an RC helicopter to an electric long board – this is the motor controller for you.

[Ben]’s latest update considers position encoders. Knowing how fast a motor is turning is very important to knowing how fast a wheel is turning, how much torque the motor is generating, and an awesome step in building the finest motor controller ever made.

Like the last update, [Ben] demonstrates the great control program written for this ESC. This GUI programs the microcontroller on the controller, with protection from high and low voltages and currents, high RPMs, duty cycle changes, and support for regenerative braking.

Thanks [Dudelbert] for sending this one in.

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Open Source ESC Developed for Longboard Commute

For electric and remote control vehicles – from quadcopters to electric longboards – the brains of the outfit is the Electronic Speed Controller (ESC). The ESC is just a device that drives a brushless motor in response to a servo signal, but in that simplicity is a lot of technology. For the last few months, [Ben] has been working on a completely open source ESC, and now he’s riding around on an electric longboard that’s powered by drivers created with his own hands.

esc-for-longboardThe ESC [Ben] made is built around the STM32F4, a powerful ARM microcontroller that’s able to do a lot of computation in a small package. The firmware is based on ChibiOS, and there’s a USB port for connection to a sensible desktop-bound UI for adjusting parameters.

While most hobby ESCs are essentially black boxes shipped from China, there is a significant number of high performance RC pilots that modify the firmware on these devices. While these new firmwares do increase the performance and response of off-the-shelf ESCs, building a new ESC from scratch opens up a lot of doors. [Ben]’s ESC can be controlled through I2C, a UART, or even a CAN bus, greatly opening up the potential for interesting electronic flying machines. Even for ground-based vehicles, this ESC supports regenerative braking, sensor-driven operation, and on-board odometry.

While this isn’t an ESC for tiny racing quadcopters (it’s complete overkill for that task) this is a very nice ESC for bigger ground-based electric vehicles and larger aerial camera platforms. It’s something that could even be used to drive a small CNC mill, and certainly one of the most interesting pieces of open source hardware we’ve seen in a long time.

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BLDC Controller With The Teensy 3.1

[Will] is on the electric vehicle team at Duke, and this year they’re trying to finally beat a high school team. This year they’re going all out with a monocoque carbon fiber body, and since [Will] is on the electronics team, he’s trying his best by building a new brushless DC motor controller.

Last year, a rule change required the Duke team to build a custom controller, and this time around they’re refining their earlier controller by making it smaller and putting a more beginner-friendly microcontroller on board. Last years used an STM32, but this time around they’re using a Teensy 3.1. The driver itself is a TI DRV8301, a somewhat magical 3 phase 2A gate driver.

The most efficient strategy of driving a motor is to pulse the throttle a little bit and coast the rest of the time. It’s the strategy most of the other teams in the competition use, but this driver is over-engineered by a large margin. [Will] put up a video of the motor controller in action, you can check that out below.

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Electric Bubblegum Board

The Mini Maker Faire in Atlanta was packed with exciting builds and devices, but [Andrew’s] Electric Bubblegum Boards stood out from the rest, winning the Editor’s Choice Award. His boards first emerged on Endless Sphere earlier this summer, with the goal of hitting all the usual e-skateboard offerings of speed, range, and weight while dramatically cutting the cost of materials.

At just over 12 pounds, the boards are lightweight and fairly compact, but have enough LiFePO4’s fitted to the bottom to carry a rider 10 miles on a single charge. A Wii Nunchuck controls throttle, cruise control, and a “boost” setting for bursts of speed. The best feature of this e-skateboard, however, is the use of 3D-printed parts. The ABS components not only help facilitate the prototyping process, but also permit a range of customization options. Riders can reprint parts as necessary, or if they want to just change things up.

[Andrew’s] board is nearing the 11th hour over at his Kickstarter page, so swing by to see a production video made for potential backers, or stick around after the break for some quick progress and demo videos.

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Solar Powered Lawn Mower Cuts the Grass So You Don’t Have To

MowerFea2

It takes a lot of power and energy to keep grass levels down to an appropriate level; especially when it’s hot out. If cool glasses of lemonade aren’t around, the task at hand may not be completed any time soon causing the unkempt blades of green (or yellow) vegetation outside to continue their path of growth towards the sun.

Instead of braving the oven-like temperatures which will inevitably drench the person in sweat, this solar powered robot has been created ready to take on the job. With the heart of an Arduino, this device shaves down the grass on a regular basis, rather than only chopping down the material when it gets too long. This helps to save electricity since the mower is only dealing with young and soft plants whose heads are easily lopped off without much effort.

Internally, the robot’s circuitry interfaces with an underground wiring system that defines the cutting zones within the lawn, and proves to be a simple, accurate, and reliable approach to directing the robot where to go. If the device travels under a shaded area, a battery kicks in supplying energy to the engine. When sunlight is available, that same battery accumulates the electricity, storing it for later.

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Aerodynamics? Super Honey Badger Don’t Give a @#*^@!

honeybadger-rcplane

[Arron Bates] is a pro R/C Pilot from Australia. He’s spent the last few years chasing the dream of a fixed wing plane which could perform unlimited spins. After some promising starts with independently controlled wing spoilers, [Arron] went all in and created The Super Honey Badger. Super Honey Badger is a giant scale R/C plane with the tail of a helicopter and a soul of pure awesome.

Starting with a standard 87″ wingspan Extra 300 designed for 3D flight, [Arron] began hacking. The entire rear fuselage was removed and replaced with carbon fiber tubes. The standard Extra 300 tail assembly fit perfectly on the tubes. Between the abbreviated fuselage and the tail, [Arron] installed a tail rotor from an 800 size helicopter. A 1.25 kW brushless motor drives the tail rotor while a high-speed servo controls the pitch.

[Arron] debuted the plane at HuckFest 2013, and pulled off some amazing aerobatics. The tail rotor made 540 stall turn an easy trick to do – even with an airplane. Flat spins were a snap to enter, even from fast forward flight! Most of [Arron’s] maneuvers defy any attempt at naming them – just watch the videos after the break.

Sadly, Super Honey Badger was destroyed in May of 2014 due to a structural failure in the carbon tubes. [Arron] walked away without injury and isn’t giving up., He’s already dropping major hints about a new plane (facebook link).

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A 3D Printed Brushless Motor

brushlessBuilding electronics with 3D printers is something we see hitting the tip line from time to time, but usually these are printed circuits, not electromechanical parts like motors, solenoids, and relays. [pitrack] thought he could do better than printing out a few blinking LED circuits and designed and built a brushless motor, the same kind you would find on electric model planes and quadcopters.

In every brushless DC motor, there are a few common parts: the rotor has a few powerful magnets embedded in it, a stators with coils of wire, and the an enclosure to keep everything together. [pitrack] printed all these parts off on his Makerbot, winding each of the three coils with about 400 turns of 26 AWG magnet wire. Also embedded in the stator are a trio of hall effect sensors to make the control via an Arduino and an L6234 motor driver easy.

For his next trick, [pitrack] is going to test the efficiency of the motor and attempt to optimize it. In the long term, it should be possible to parameterize the design of one of these printed motors, effectively allowing anyone to type in the torque and Kv rating of a desired motor, plug that into an equation, and have a motor design come out the other end.
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