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. 2022 Apr 15;13(4):627.
doi: 10.3390/mi13040627.

Design of a Biologically Inspired Water-Walking Robot Powered by Artificial Muscle

Dongjin Kim  1 , Minseok Gwon  1 , Baekgyeom Kim  1 , Victor M Ortega-Jimenez  2 , Seungyong Han  1 , Daeshik Kang  1 , M Saad Bhamla  2 , Je-Sung Koh  1
Affiliations

Design of a Biologically Inspired Water-Walking Robot Powered by Artificial Muscle

Dongjin Kim et al. Micromachines (Basel). .

Abstract

The agile and power-efficient locomotion of a water strider has inspired many water-walking devices. These bioinspired water strider robots generally adopt a DC motor to create a sculling trajectory of the driving leg. These robots are, thus, inevitably heavy with many supporting legs decreasing the velocity of the robots. There have only been a few attempts to employ smart materials despite their advantages of being lightweight and having high power densities. This paper proposes an artificial muscle-based water-walking robot capable of moving forward and turning with four degrees of freedom. A compliant amplified shape memory alloy actuator (CASA) used to amplify the strain of a shape memory alloy wire enables a wide sculling motion of the actuation leg with only four supporting legs to support the entire weight of the robot. Design parameters to increase the actuation strain of the actuator and to achieve a desired swing angle (80°) are analyzed. Finally, experiments to measure the forward speed and angular velocities of the robot are carried out to compare with other robots. The robot weighs only 0.236 g and has a maximum and average speed of 1.56, 0.31 body length per second and a maximum and average angular velocity of 145.05°/s and 14.72°/s.

Keywords: SMA actuator; biologically inspired robots.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Image of a water-walking microrobot.
Figure 2
Figure 2
Fabrication of an actuator and a robot. (a) Components of a compliant amplified SMA actuator (CASA); (b) Schematic of an assembled CASA actuating with voltage on and off; (c–h) fabrication steps for a robot composed of fixed frames, actuators and moving frames connected by interlocking component, supporting legs and actuating leg.
Figure 3
Figure 3
Design and performance of a CASA. (a) Image of actuation of a CASA; (b) experimental setup to measure actuation strain of a CASA; (c) actuation strain for different length of SMA wire length; (d) actuation stroke of a single actuator and a stack of double actuators.
Figure 4
Figure 4
Image and illustration of a side view of robot showing rowing mechanism. (a) Schematics of vertically and horizontally moving components; (b) first degree of freedom, back-and-forth actuating leg rotation; (c) second degree of freedom, up-and-down actuating leg rotation.
Figure 5
Figure 5
Design parameters for desirable angle of actuating leg. (a) Schematic top view of a robot; (b) enlarged schematic noted as dashed rectangle in top-view schematic; (c) schematic of moving frames and actuating leg before and after actuation with parameters for desirable angle of an actuating leg.
Figure 6
Figure 6
(a–f) Photo snapshots of rowing actuating leg trajectory in the air.
Figure 7
Figure 7
Image of a water-walking microrobot. (a–d) Sculling motion on the water; photo snapshots of robot (e) moving forward and (f) turning.
Figure 8
Figure 8
Experimental results of forward and turning motion. (a) Image of the robot indicating its body length (9 cm); (b) distance during forward motion of a robot; (c) velocity of the robot moving forward; (d) turning angle during turning motion of a robot; (e) angular velocity of the robot.
Figure 9
Figure 9
Comparison of weight, speed and angular velocity of water-walking robots. (a) Average speed and weight; (b) average angular velocity and weight.
See this image and copyright information in PMC

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