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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.

This work proposes a two-dimensional (2-D) laser scanning mirror with a novel actuating structure composed of one magnet and two coils. The mirror-actuating device generates decoupled scanning motions about two orthogonal axes by combining two electromagnetic actuators of the conventional moving-coil and the moving-magnet types. We implement a finite element analysis to calculate magnetic flux in the electromagnetic system and experiments using a prototype with the overall size of 22 mm (W) × 20 mm (D) × 15 mm (H) for the mirror size of 8 mm × 8 mm. The upper moving-coil type actuator to rotate only the mirror part has the optical reflection angle of 15.7° at 10 Hz, 90°at the resonance frequency of 60 Hz at ±3V(±70mA) and the bandwidth of 91 Hz. The lowermoving-magnet type actuator has the optical reflection angle of 16.20°at 10 Hz and50°at the resonance frequency of 60 Hz at ±5V(±34mA) and the bandwidth of 88 Hz. The proposed compact and simple 2-D scanning mirror has advantages of large 2-D angular deflections, wide frequency bandwidth and low manufacturing cost.

In this study, novel modular shape memory alloy wire–based torsional actuators were designed and fabricated. These shape memory alloy–based actuators provide rotational displacements. The mechanical and thermal properties of a single module shape memory alloy torsional actuator were characterized. Next, a modular shape memory alloy torsional actuator was configured by connecting single actuator modules in series. This modular actuator can be used directly as a soft or biologically inspired robot. Finally, the rolling motion and shape transformation of the modular shape memory alloy torsional actuator (soft robot) were demonstrated with a simple open-loop-based control scheme experimentally validating the novel mobility and actuation of the proposed actuator. For a control input, sequentially coordinated square waves of electric current were supplied to the shape memory alloy actuating units.

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