FIGURE 6 - available via license: Creative Commons Attribution 4.0 International
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| Overview of the robot locomotion velocity under different actuation amplitudes and frequencies. 1) Overall velocity range is suppressed to show more low-velocity details; and 2) white contour line shows the zerovelocity separation.
Source publication
Inchworm-styled locomotion is one of the simplest gaits for mobile robots, which enables easy actuation, effective movement, and strong adaptation in nature. However, an agile inchworm-like robot that realizes versatile locomotion usually requires effective friction force manipulation with a complicated actuation structure and control algorithm. In...
Contexts in source publication
Context 1
... instead of directly controlling the friction forces, the proposed "implicit controller" controls the deformation amplitude and frequency of the robot via choosing proper actuation input, as shown in Eq. 4; then, the combination of the two differential friction forces and the locomotion of the robot is indirectly controlled. Figure 6 presents an overview of the robot locomotion velocity under different actuation amplitudes and frequencies. The white contour line of zero velocity helps divide the whole map into positive velocity regions and negative velocity regions. ...
Context 2
... robot achieved relatively high energy efficiency (CoT < 1) in a large part of the result, while the low actuation magnitude region had relatively low energy efficiency. In addition, by comparing with the corresponding velocity result map (Figure 6), the CoT got a notable high value around the contour line of zero velocity, which is understandable considering its definition in Eq. 6. ...
Citations
... Earthworms create forward movement by contracting and extending their body segments to create a wave-like motion [8] [ Figure 1]. This pattern of contraction and extension from front to rear is called peristalsis and can be seen in other annelids and legless insects [11] . On the other hand, inchworms use an inching motion to propel themselves forward by anchoring the surface with the front of their body whilst contracting the middle and then extending their middle whilst anchoring the surface with the back of the body [12] . ...
... Inchworm robots are defined by having two gripping units on either side of a central extension unit, though they may also have a separate bending unit or have bending integrated into the extension unit. These robots may be connected in series to make such a modular device resemble an earthworm robot [11] . The units can be connected by rigid parts or the whole robot can be made from flexible material. ...
In recent years, the development of worm-like robots has increased significantly. These robots use peristaltic motion comprised of radial expansion and axial elongation to move leglessly through their environments. Soft worm-like robots have the advantage of conforming to their environment, making them ideal for confined spaces such as pipelines which are essential to societal infrastructure. Pipeline contamination and corrosion can be detrimental and costly and thus regular checking is vital. Some pipes are difficult to access due to size, access restrictions and harmful waste contamination (such as in nuclear power plants). This has led to an increase of research into soft worm-like robots for pipe inspection. This review will analyse the recent progress in this area to assess current robotic capabilities and where work may be further needed to ensure they are applicable to real-world applications.
... Some other robots use multiple layers of materials to function, which increases complexity [23]. Finally, researchers studied crawling using static [28] and dynamic analyses [7,29,34]. The resulting mathematical modeling is, in any case, intricate. ...
Nonskeletal animals such as worms achieve locomotion via crawling. We consider them as an inspiration to design robots that help underline the mechanisms of crawling. In this paper, we aim to identify an approach with the simplest structure and actuators. Our robots consist of cut-and-fold bodies equipped with pneumatically-driven soft actuators. We have developed fabrication techniques for coin-sized robots. Experiments showed that our robots can move up to 4.5 mm/s with straight motion (i.e., 0.1 body lengths per second) and perform cornering and U-turns. We have also studied the friction characteristics of our robots with the ground to develop a multistate model with stick–slip contact conversions. Our theoretical analyses depict comparable results to experiments demonstrating that simple and straightforward techniques can illustrate the crawling mechanism. Considering the minimal robots’ structure, this result is a critical step towards developing miniature crawling robots successfully.
... Crawling by inchworms is a common locomotion strategy among soft creatures and crawler robots [12], [13]. These crawlers can move forward by bending their bodies and switching between stick and slip transitions at the contact locations, all the while maintaining ground contact. ...
This study presents a soft crawler robot based on fluidic prestressed composite (FPC) actuators. The robot is precurved and is actuated by pneumatic pressure. Prestress is applied to an elastomeric matrix composite (EMC) layer in the actuator, resulting in precurved shapes, high stiffness, and zero energy costs in maintaining curved shapes. A crawler robot prototype is fabricated, and the fabrication process is presented. The robot's capability to efficiently crawl is demonstrated using two one-way wheels with uni-directional frictional characteristics. The fabricated crawler has shown multiple favorable characteristics, including low mass (45~g), large step size (73.2~mm), and high speed (95~mm/s). In additon, the robot's response time to pressurized deformation and unpressurized restoration is less than 125~ms. It is found that higher pressure can generate longer step sizes, greater velocity, and quicker responses.
