Every few months or so, a new video from Boston Dynamics will make the rounds on the Internet. This is their advertising, because unless the military starts buying mechanical mules, Boston Dynamics is going to be out of business pretty soon. You’ll see robots being kicked down the stairs, robots walking through doors, and robots acting like dogs. If a hundred or so highly skilled and highly educated roboticists, technologists, and other experts can put together a walking dog robot in a decade, obviously one person can cut through the cruft and build one in a basement. That’s what [Misha] is doing. It’s the Dizzy Wolf, a robotic wolf, or dog, or cat, we don’t actually know because there’s no fur (or head) yet. But it is interesting.
The key component for any quadruped robot is a high-torque, low-noise servo motor. This isn’t a regular ‘ol brushless motor, and for this application nine gram servos go in the trash. This means custom made motors, or DizzyMotors. You’re looking at a big brushless motor with a planetary gearset, all squished into something that could actually fit into the joint of a robotic wolf’s leg.
There’s a driver for these motors, strangely not called the DizzyDriver, that turns a BLDC into a direct drive servo motor. It is effectively a smart servo, that will move to a specific rotation, receive commands over RS-485, and write back the angular position. It also applies constant torque. Of course, there is a video of the DizzyMotor and servo driver below.
Building a robotic dog that will walk around the house is one of the hardest engineering challenges out there. You’ve got fairly crazy kinematics, you’ll need to think about the strength of the frame, control systems, and eventually how to fit everything in a compact design. This project is hitting all the marks, and we can’t wait to see the Dizzy Wolf do a backflip or chase a ball.
Continue reading “A Pet Robot, Just Like Boston Dynamics Makes”
Driving a brushless motor requires a particular sequence. For the best result, you need to close the loop so your circuit can apply the right sequence at the right time. You can figure out the timing using a somewhat complex circuit and monitoring the electrical behavior of the motor coils. Or you can use sensors to detect the motor’s position. Many motors have the sensors built in and [Electronoobs] shows how to drive one of these motors in a recent video that you can watch below. If you want to know about using the motor’s coils as sensors, he did a video on that topic, earlier.
The motor in question was pulled from an optical drive and has three hall effect sensors onboard. Having these sensors simplifies the drive electronics considerably.
Continue reading “Completely Scratch-Built Electronic Speed Controller”
One of the more interesting yet underrated technological advances of the last decade or so is big brushless motors and high-capacity batteries. This has brought us everything from quadcopters to good electric cars, usable cordless power tools, and of course electric bicycles. For his Hackaday Prize project, [marcus] is working on a very powerful electric bicycle controller. It can deliver 1000 Watts, it’s got Bluetooth, and there’s even an Android app for some neat diagnostics.
The specs for this eBike controller are pretty much what you would expect. It’s able to deliver a whole Kilowatt, can use 48 V batteries, has regenerative braking, Hall sensors, and has a nifty Android app for settings, displaying speed, voltage and power consumption, diagnostics, and GPS integration.
How is the project progressing? [marcus] has successfully failed a doping test. He lives on the French Riviera, and the Col de la Madonne is a famous road cycling road and favorite test drive of [Lance Armstrong]. The trip from Nice to Italy was beautiful and ended up being a great test of the eBike controller.