Small robotics builds with three wheels are plentiful. The most typical configuration is to have the two front wheels drive and turn the vehicle in a skid-steer configuration. The third wheel is often a simple caster. However, this isn’t the only way to go, and [markus.purtz] has put together a build that does things differently.
The build is a small, radio-controlled FPV trike. Instead of the usual skid-steer setup, the rear wheel is mounted on a pair of horizontal bearings which allows it to pivot left and right. A servo is used to control the rear wheel position, with a pair of tie rod ends used to connect the horn to the rear steering assembly. It’s not the only unconventional design choice, either – magnets are used to affix the top plate to the vehicle chassis, rather than screws or clips. For video, the user can mount either a small dedicated FPV camera, or a GoPro with the included mount.
Without any code or control details posted, we can’t be 100% sure how it all works. However, from the video, it appears that both front wheels are being driven at the same speed, with steering handled solely by the rear wheel. This is apparent when driving on a smooth surface, where the vehicle can be seen to slide when turning. While it’s unlikely this setup has many advantages over a simpler differential steering build with a caster, it does show that rear steering can be effective on its own.
It’s a build that shows off the benefits of using proper bearings and mechanical parts in a design. With today’s online marketplaces, it’s never been easier to find what you need. Parts are on Thingiverse for those interested in replicating the design. Meanwhile little FPV bots remain popular, and we’re sure we’ll continue to see them coming in. Video after the break.