Tag Archives: fins

Robot Pigeon Uncovers the Secrets of Bird Flight without Vertical Caudal Fins

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A pigeon-inspired robot has uncovered the mystery of bird flight without vertical tails found in human-designed aircraft. The prototype has the potential to lead to passenger planes that can reduce drag and fuel consumption.

The vertical stabilizer, or tail fin, in aircraft allows for side-to-side turns and prevents unintentional changes in direction. Some military aircraft, like the Northrop B-2 Spirit, are designed without tails to reduce radar visibility. Instead, they use inefficient methods like flaps creating extra resistance on one side.

Research by David Lentink at the University of Groningen in the Netherlands led to the development of the PigeonBot II to study how birds maintain control without vertical stabilizers.

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PigeonBot II, a robot designed to imitate bird flight techniques

Eric Chan

The previous model, built in 2020, mimicked bird flight by flapping wings but had a traditional tail. The new design, featuring 52 real pigeon feathers, incorporates a bird-like tail, and successful test flights confirm its functionality.

Lentink explains that PigeonBot II’s success lies in its programmed, reflexive tail movements resembling those of birds. The intricate tail movements contribute to stability, proven by the robotic replica’s flight.

The team controlled PigeonBot II’s nine servo motors, utilizing propellers on each wing for steering and tail adjustments in response to the autopilot’s commands. Lentink notes that the complexity of these reflex movements prevents direct human control of PigeonBot II.

After numerous unsuccessful tests, the control system was refined, enabling safe takeoff, cruising, and landing. Lentink envisions a future where vertical stabilizers are unnecessary, reducing weight and drag in aircraft designs.

Source: www.newscientist.com

Folding fins increase the speed of fish movement, as demonstrated by Robot Tuna

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This tuna-inspired robot borrows some nifty tricks from the real fish

Lin, Z. et al. (2024).

The tuna-shaped robot harnesses the secret to the speed and agility of real fish – the ability to selectively fold and extend their fins – which could improve underwater robot design.

Tuna are one of the fastest swimming fish in the ocean, thanks in part to their ability to retract and fold their fins to reduce drag. Chung-Rok Hayashi Researchers from China's Xiamen University and their colleagues investigated how such fins could improve the agility of robots.

The researchers built a 50-centimeter-long tuna-shaped robot that can be controlled by motors attached to its head, a dorsal fin on its back, and a fluke at the end of its tail. The researchers filmed the robot swimming in a pool and tested the effects of flattening or erecting the dorsal fin on the robot's acceleration, direction changes, and steady forward motion.

They found that folding and unfolding the dorsal fin had significant effects on factors such as speed, efficiency and linear acceleration. When the robot tuna was changing direction, keeping the dorsal fin erect increased its speed by about 33%. However, keeping the fin erect when the robot was moving steadily forward reduced the efficiency of its movement by up to 13%, increasing the robot's energy consumption.

Lin says these findings are consistent with how tuna in nature raise their dorsal fin to make fast, precise movements, such as when catching prey, then fold it back to continue swimming. “By designing similar flexible control systems, underwater vehicles can improve balance, navigation, and agility at high speed,” he says.

“Understanding this high level of swimming performance in tuna is intrinsically interesting because it is something that even the best human swimmers cannot achieve.” Frank Fish At West Chester University in Pennsylvania.

But Fish adds that the tail fin may play a bigger role than the dorsal fin in a tuna's swimming ability. His own research Many of these animals have shown this to be especially true when it comes to turning, Fish says. “We measured the turning ability of Pacific bluefin tuna and found that it far surpasses the capabilities of a robot,” he says. This may mean that tuna-inspired robots could also be improved by studying their tails in more detail.

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Source: www.newscientist.com