The most versatile ground-based robots are bipedal, just like us humans. When it comes to uneven or otherwise difficult terrains, they are much more capable at getting around than even wheeled or tracked robots. Yet bipedal robots are much less common because they are far more difficult and expensive to design and control. Their supporting sensing and navigation systems are considerably more complex, and failures occur more frequently and more spectacularly.
A research group at Carnegie Mellon University is working to make bipedal robots more reliable and simpler to control. To understand how this might be possible, they are first working at a smaller scale than these machines are typically found in. In fact, they have developed what they claim to be the world’s smallest bipedal robot. Their creation, called Zippy , is about the same height as a LEGO minifigure — although it is quite a bit wider.
Zippy’s locomotion is powered by just a single motor, with a Seeed Studio XIAO microcontroller development board for control. This simple setup does make for a somewhat awkward and wobbly walking gait, but it is effective all the same.
Despite its small size of just under 1.5 inches tall, Zippy can do more than just walk. It is capable of starting from a standstill, turning, skipping, and even climbing small steps. All of these movements are made possible by a clever mechanical design. First, the robot’s front leg lifts to shift Zippy’s center of gravity. This motion, and the curved shape of its feet, helps to swing the rear leg forward a full step with a mechanical hard stop acting as a joint limit for its hip.
At an average speed of 10 leg lengths per second, or half-a-mile per hour, Zippy is well, pretty zippy. If we could move at that rate, we would be zooming along at 19 miles per hour.
The researchers see real-world potential for Zippy in applications like search and rescue, industrial inspections, and scientific exploration, where its tiny size allows it to access tight spaces that are off-limits to larger machines. But first, their next steps include equipping the robot with sensors such as cameras to enable autonomous navigation and localization. With this added functionality, multiple robots could operate cooperatively as a swarm, potentially exploring hazardous environments that are too dangerous for humans.The world’s smallest bipedal robot (📷: College of Engineering, Carnegie Mellon University)
Zippy the robot. LEGO head optional, but strongly encouraged (📷: Carnegie Mellon University)