I’ve already talked about several awesome robots that you could, in theory, make yourself, but one thing that all of them have in common is that they move around on wheels or tracks.
Here is another set of hobbyist robots that not only can you build yourself, but walk on two, four, or even six legs!
Walk on Two Legs with BOB
Perhaps counter-intuitively, up to a point, the fewer legs you have on a robot, the harder it is to make. One-legged machines are technically possible, but I personally wouldn’t have the skill to write the control software for something like this self-balancing robotic Pogo stick (watch above).
Two legs are somewhat easier, but that still creates the challenge of having to balance on one leg while the other moves. In order to partially circumvent the balance issue, makers have come up with two interesting solutions called BOB and Otto.
This type of robot literally bobs around, shifting its weight from one leg to another, using four servos to walk in a rather strange gait. Their “eyes” are made from an ultrasonic sensor, and since the robot rotates its head-body back and forth when walking, this should allow it to scan the area for object avoidance. Or you can forgo this sensor altogether and simply program it to dance as shown below.
Although four legs would seem to be easier, these robots present the same sort of challenges as their two-legged brethren. Unless the weight was somehow allowed to shift like with BOB, the robot becomes unstable when any leg moves. Though you’ll find solutions that sort of slide around like the “Hermes” quadruped, it’s a difficult task to do well without a solid grasp on the mechanics and control theory.
On the other hand, some people do understand this, as the “Stag Mk2” shown below. This amazing little bot appears to use two servos per leg for locomotion, and is reminiscent of the Big Dog robot from Boston Dynamics.
One might question the “amateur” status of the creators of this robot, but it appears to be walking around on textbooks inside of a college-style apartment. Glad to see these books being put to good use. Years after graduating, I can say that I still use several of my engineering textbooks every day. Unfortunately, they are supporting my computer monitor.
Six or More Legs
Once you get to six or more legs for your robot, this is where a bot can be constructed that is stable without high-level control design. Through several different schemes, these bots are able to move legs as needed while still being able to contact the ground in three or more points.
Though these robots can be constructed with as few as three servos (moving pairs of legs in tandem), below is an example of one with twelve servos for the legs, plus actuation to allow the sensor module to look around. It seems to move from point to point well and avoid obstacles, but be sure to watch just after 1:00 when it shows off some of its fancier moves.
It should also be noted that the same channel also has an advanced two leg BOB-style robot. If you’d like to build a hexapod but don’t think you have the mechanical skills to build one, the good there are many kits available. A quick Internet search should reveal many options for your next build.
How to Make It Work
Now that you have a few ideas of how to make your next robot mechanics-wise, perhaps you should consider what computing platform to use to run it. Here are five excellent ideas for your robot’s brain.