Swimming Robot Channels Its Inner Dog to Master the Dog Paddle

While quadruped “robot dogs” can mimic the way real dogs move on land with relative accuracy, their swimming skills often fall short—although some can walk underwater. That’s not the case for a newly developed small-scale robot, designed specifically to swim efficiently using the classic dog paddle.

Introducing the Amphibious Robot Dog (ARD)

Named the Amphibious Robot Dog (ARD), the robot measures 30 cm in length and 10 cm in width, weighing approximately 2.25 kg. It was developed by a research team led by Professors Yunquan Li and Ye Chen from the South China University of Technology.

On land, the ARD uses a trotting gait powered by double-jointed legs, reaching speeds of up to 1.2 body lengths per second. In water, despite increased resistance, it still manages to swim at 0.54 body lengths per second—a performance comparable to real dogs, which reach about 1.4 BL/s when dog paddling, according to previous studies.

Rather than simply making a waterproof quadruped, the researchers carefully adjusted the ARD’s center of gravity and buoyancy to ensure stable and effective aquatic motion. They also tested three different swimming gaits.

Dog Paddle Variants: LSPG Gaits

Two of these styles were variations of the dog paddle, termed “lateral sequence paddling gaits” (LSPGs). These involved moving the robot’s four legs in a specific sequence: left front, left rear, right front, and right rear.

The two LSPG versions differ in how long each leg stays in the ‘power phase’—the part of the cycle when the leg extends to generate thrust.In one version, legs moved independently with 25% of the cycle spent in the power phase. In the other, leg movements overlapped, increasing the power phase to 33%, more closely resembling the natural dog paddle.

The third swimming style, called the “trot-like paddling gait” (TLPG), had diagonally opposed leg pairs move simultaneously—left front with right rear, then right front with left rear—resulting in a 50% power phase.

Pool tests showed that the 33% LSPG was the fastest, achieving 0.54 BL/s, followed closely by the 25% version. The TLPG was the slowest but proved to be the most stable.

This innovation represents a major step in the development of nature-inspired robotics, said Professor Li. Our robot dog’s ability to move efficiently both on land and in water comes from its bioinspired trajectory planning, which mimics the natural paddling motion of real dogs.

Read the orignal article on: New Atlas

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