Introduction to Amphibious Robot Dog
Quadruped "robot dogs" may move quite a bit like their canine counterparts on land, but they’re not nearly as good at swimming, although some can walk underwater. However, a new mini-dog-bot is an expert at doing the dog-paddle. Known as the Amphibious Robot Dog (ARD), this four-legged device measures 300 mm long by 100 mm wide and weighs 2.25 kg.
Design and Features of ARD
The ARD was created by a team of scientists led by professors Yunquan Li and Ye Chen from the South China University of Technology. On land, the robot’s double-jointed legs adopt a trotting gait, taking it to a top speed of 1.2 BL/s (body-lengths per second). Swimming in the water, it still manages a decent 0.54 BL/s. For comparison, previous research indicates that actual pooches top out at about 1.4 BL/s when dog-paddling.
Swimming Styles of ARD
The scientists made a point of balancing the robot’s center of gravity and center of buoyancy to ensure stable and effective aquatic performance. They also experimented with three different swimming styles. Two of these, called "lateral sequence paddling gaits" (LSPGs), were essentially variations on the dog-paddle. As the name suggests, they involved moving the four legs in a lateral sequence/cycle – left-front then left-rear, followed by right-front then right-rear.
Lateral Sequence Paddling Gaits (LSPGs)
The difference between the two LSPG gaits lay in what proportion of the cycle each leg spent in the "power phase" (PP), in which it was fully extended for maximum thrust. In one gait, each leg moved completely on its own, for a PP proportion of 25%. In the other – which was more like the natural dog-paddle – there was some overlap between leg movements, for a PP proportion of 33%.
Trot-Like Paddling Gait (TLPG)
The third swimming style was a "trot-like paddling gait" (TLPG) in which diagonally-opposed pairs of legs moved at the same time – left-front/right-rear, then right-front/left-rear – for a 50% PP proportion.
Performance of ARD
Pool tests showed that the 33% LSPG delivered the fastest swimming speed of 0.54 BL/s, followed closely by the 25% LSPG. The TLPG was the slowest of the three, but it was also the most stable. According to Prof. Li, "This innovation marks a big step forward in designing nature-inspired robots. Our robot dog’s ability to efficiently move through water and on land is due to its bioinspired trajectory planning, which mimics the natural paddling gait of real dogs."
Conclusion
The Amphibious Robot Dog is a significant innovation in the field of robotics, with its ability to efficiently move through water and on land. Its bioinspired design and trajectory planning make it an expert at doing the dog-paddle, with a top swimming speed of 0.54 BL/s. The research on ARD has been published in the journal Bioinspiration and Biometrics, and it is expected to inspire further developments in the field of nature-inspired robots.
