All About Mecanum

January 20, 2022 by Al Williams 14 Comments

If you’ve dealt with robots or other wheeled projects, you’ve probably heard of mecanum wheels. These seemingly magic wheels have the ability to move in any direction. If you’ve ever seen one, it is pretty obvious how it works. They look more or less like ordinary wheels, but they also have rollers that rotate off-axis by 45 degrees from the normal movement axis. This causes the wheel’s driving force to move at a 45 degree angle. However, there are a lot of details that aren’t apparent from a quick glance. Why are the rollers tapered? How do you control a vehicle using these wheels? [Lesics] has a good explanation of how the wheels work in a recent video that you can see below.

With four wheels, you can have a pair of wheels — one at the front right and one at the back left — that have a net force vector of +45 degrees. Then the other pair of wheels can be built differently to have a net force vector of -45 degrees. The video shows how moving some or all wheels in different directions can move the vehicle in many different directions.

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Peek Behind The Curtain Of This Robotic Mouse

January 9, 2022 by Tom Nardi 9 Comments

At first glance, this little animatronic mouse might seem like a fairly simple affair. A door opens, our rodent friend pops its head out, looks around, and goes back in. But just like in The Wizard of Oz, a strategically placed curtain is hiding the impressive array of gadgetry that makes the trick possible.

Creator [Will Donaldson] has put together a fantastic write-up of just what went into creating this little fellow, and we think you’ll be surprised at just how serious the mechanics involved are. Take for example the rig that provides horizontal motion with a NEMA 17 stepper motor mated to a 200 mm leadscrew and dual 8 mm rail assembly that would like right at home as part of a 3D printer.

The star of the show rides atop a beefy sliding carriage assembly made of printed components and acrylic, which is linked to the door via a GT2 timing belt and pulley in such a way that it automatically opens and closes at the appropriate time. To inject some life into the puppet, [Will] stuffed it with a pair of SG90 servos in a sort of pan-and-tilt arrangement: the rear servo turns the mouse’s body left and right, while the forward one moves the head up and down.

An Arduino Uno controls the servos, as well as the stepper motor by way of a TB6600 controller, and optical limit switches are used to make sure nothing moves out bounds. [Will] is keeping the CAD files and source code to himself for the time being, though we imagine a sufficiently dedicated mouseketeer could recreate the installation based on the available information.

This would appear to be the first animatronic mouse to grace the pages of Hackaday, but we’re certainly no strangers to seeing folks imbue inanimate objects with lifelike motion.

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Metal mechanoid security patrol ride-on made from scrap

Homemade Scrapyard Security Mech Gives Uncle Super Powers

January 3, 2022 by Dave Rowntree 26 Comments

[Handy Geng] is back again with another bonkers build, that we just can’t not cover. His Uncle came to visit the workshop one day and said he’d love to go there every day, and could even watch over it when [Handy Geng] was away. But being an older chap and needing a stick to get around, he would not be much use if ‘bad guys’ decided to pay a visit. The obvious solution was to build a ride-on security mech which Uncle could ride on, (video, embedded below) and use to defend the shop from bandits.

The build starts with him unloading a large pair of tracked wheel units from his truck, which caused a chuckle around these parts when we tried to imagine the scrap yard he’d just visited! The build video is more of a spot-weld-come-assembly log, with the less interesting sub assembly construction omitted. If he’d included all the details, this video would have been hours long. Though, we’d probably watch that anyway.

Features of the final construction include, but not limited to, dual motors for on-the-spot turns, night-time patrol lights, dual pneumatic fists for attack mode, dual water cannons for a more gentle approach and rear facing speakers blasting out Chinese opera for the ultimate deterrent. Practical touches include an integrated glasses case for the ready-readers, and a walking cane holder, so the mech was Uncle-ready. He seemed impressed from the grin on his face!

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When A Ball Robot Becomes Two Wheels

December 30, 2021 by Jenny List 8 Comments

It’s now about six years since Star Wars: The Force Awakens first showed us the little spherical robot BB-8, but it’s fair to say that along the way we’ve not lost our collective fascination for rolling-ball robots. There have been plenty of attempts to make a fully-rolling device, but perhaps [Derek Lieber] has a better take on it by turning a spherical robot into a two-wheeled roller by the addition of a pair of tyres. Inspired by a Samsung prototype that never made it to market, it works by the wheels working against the machine’s low centre of gravity, and using a tilt sensor to control speed.

The ball chassis is a 3D printed shell, into which after much experimentation with motors, the final version put a pair of gimbal motors with a set of magnetic position sensors. Inside is an Arduino Mega and a custom motor driver board sporting an LM6234, with an XBee radio for remote control. Meanwhile the power comes from a set of three LiPo cells, and there is some extra lead ballast in the bottom to keep the whole thing balanced.

We’ve seen more conventional takes on a spherical robot in the past, but we’re particularly keen on this one, and excited to see where the future takes it.

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Robot Delivery To Your Door

December 29, 2021 by Chris Lott 20 Comments

While online shopping was already very popular in South Korea, it has become even more so as people stay home more during the pandemic. Several robotic delivery services have launched around the city, such as 7-Eleven using the Neubie robot by Neubility, the GS25 convenience store using LG’s CLOi ServeBot, and the Baemin food delivery service using the Delidrive robot.

Love it or hate it, in the dense population of big cities like Seoul the vast majority of people live in apartment complexes. This lends itself well to these robot delivery projects. In fact, many of these pilot projects are only available in one apartment complex, which can consist of ten to twenty 15+ story buildings. Training your robot to navigate the sidewalks, operating the doors, calling the elevators, and buzzing the customer’s home intercom is an easier task when dealing with only one campus.

Some projects are more ambitious, like another Neubility system operating on the Yonsei University Songdo City campus. You can order fried chicken and have it delivered by a Neubie robot, which comes to your address along the sidewalk at a brisk 5 to 6 km/h. There are some issues, however. First of all, government regulations haven’t quite kept up with the technology. These services are basically operating case-by-case, temporary waiver basis. They are not allowed to operate on the streets, and when driving on the sidewalks they have to avoid bumping into people.

We wrote about a prototype RC truck delivery system last year, and covered Amazon drones and Automating Freight Delivery as well. These all show promise, but are not mainstream yet. The vast majority of your orders are still delivered by a person. Will these automated delivery services eventually replace humans? Let us know your thoughts in the comments below.

Do You Need A Cycloidal Drive?

December 25, 2021 by Elliot Williams 9 Comments

A cycloidal gear drive is one of the most mesmerizing reduction gears to watch when it is running, but it’s not all just eye-candy. Cycloidals give decent gearing, are relatively compact and back-drivable, and have low backlash and high efficiency. You probably want one in the shoulder of your robot arm, for instance.

But designing and building one isn’t exactly straightforward. Thanks, then, to [How To Mechatronics] for the lovely explanation of how it works in detail, and a nice walkthrough of designing and building a cycloidal gear reducer out of 3D printed parts and a ton of bearings. If you just want to watch it go, check out the video embedded below.

The video is partly an ad for SolidWorks, and spends a lot of time on the mechanics of designing the parts for 3D printing using that software. Still, if you’re using any other graphical CAD tool, you should be able to translate what you learned.

It’s amazing that 3D printing has made sophisticated gearbox designs like this possible to fabricate at home. This stuff used to be confined to the high-end machine shops of fancy robotics firms, and now you can make one yourself this weekend. Not exotic or unreliable enough for you? Well, then, buy yourself some flexible filament and step on up to the strain wave, aka “harmonic drive”, gearbox.

Thanks to serial tipster [Keith] for the tip!

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Shake With Your New Robot Hand

December 21, 2021 by Al Williams 12 Comments

Korean researchers have created a very realistic and capable robot hand that looks very promising. It is strong (34N of grip strength) and reasonably lightweight (1.1 kg), too. There are several videos of the hand in action, of which you can see two of them below including one where the hand uses scissors to cut some paper. You can also read the full paper for details.

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