An earthworm-like actuator using segmented solenoids

Abstract

A biomimetic actuator is developed using four segmented solenoids mimicking earthworm locomotion. The proposed actuator not only has a simple structure composed of cores and coils, but also enables bi-directional actuation and high speed locomotion regardless of friction conditions. We have implemented theoretical analysis to design the optimal profiles of input current signal for maximum speed and predict the output force and stroke. Experiments using a prototype show that the earthworm-like actuator travels with a speed above 60 mm s −1 regardless of friction conditions.

Design of a Solenoid Actuator with a Magnetic Plunger for Miniaturized Segment Robots

“…In a previous work [10], we designed a four-segmented robot using solenoids mimicking the earthworm's locomotion, where the segmented robot has a high-speed rectilinear motion. However, the miniaturized robot with turning locomotion has not been implemented.…”

“…However, the miniaturized robot with turning locomotion has not been implemented. As the extension of the linear motion in the previous work [10], we design and develop a miniaturized solenoid with a ferromagnetic plunger to generate both rectilinear and turning motions of the segmented robot. We implement the theoretical analysis on the actuation force induced by the solenoid with a magnetic plunger based on the Biot-Savart law.…”

Actuation and design innovations in earthworm-inspired soft robots: A review

“…First, addition of magnetic materials or coils for constructing the robot and driving the corresponding deformation of the robot or generating deformation by altering the direction and magnitude of the external magnetic field (Saga and Nakamura, 2002a;Wang et al, 2008;You et al, 2021). Second, twist the magnetic poles inside the robot using a motor or utilize the magnetic effect of current to increase the distance between the segments to produce deformation based on the principle of heteropolar repulsion (Saga and Nakamura, 2002b;Chi and Yan, 2003;Shin et al, 2011;Song et al, 2016). You et al (2021) designed a 256 mm long robot that exhibits the highest crawler velocities for 0, 2, and 4 mm magnet separation-0.043, 0.05, and 0.0625 bl•s -1 , respectively-for a magnet velocity of 1,250 mm s -1 , just as shown in Figure 15A.…”

“…The robots with interior magnets fundamentally followed the principle of “like poles repel and unlike magnet attract each other” to alter the distance between the segments and complete axial elongation. In addition, it shortened the distance between various segments and complete axial compression through dissimilar poles ( Saga and Nakamura, 2002b ; Chi and Yan, 2003 ; Shin et al, 2011 ). On a flat surface with a roughness of 0.75, the robot designed by Shin et al ( Shin et al, 2011 ) achieved an average speed of 1.31875 bl·s –1 .…”

Semi‐active control of metal foam magnetorheological damper

“…The magnetorheological fluid dampers have the characteristics of simple structure, wide adjustable range, low energy consumption and fast response. It shows a good application region in the automobile suspension system [6–8].…”