Biologically inspired burrowing robot

Thesis (S.B.)--Massachusetts Institute of Technology, Department of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (page 27).The Atlantic razor clam (Ensis directus) burrows into soil by contracting its valves in a pattern that fluidizes the particles around it. In this way, it uses an order of magnitude less energy to dig to its burrowing depth than would be expected if it were moving through static soil. This technology is a mechanically simple solution to reduce energy requirements in applications such as anchoring and underwater pipe installation. RoboClam is a robot that imitates the movements of Ensis and has achieved localized fluidization in environments similar to that of the animal. This paper tests the theoretical timescale limits for running RoboClam while still achieving the soil fluidization that Ensis achieves. Needle valves were used on the robot's pneumatic control system to vary its expansion and contraction times in a series of tests, then each test was analyzed to determine to what extent soil fluidization occurred. It was found that the theoretical minimum contraction time is an appropriate boundary and the theoretical maximum contraction time is a loose boundary on tests that will result in soil fluidization. However, these conclusions came from a limited number of tests, so further testing is necessary to confirm these results.by Monica Isava.S.B

A Theoretical Investigation of the Critical Timescales Needed for Digging in Dry Soil Using a Biomimetic Burrowing Robot

RoboClam is a bio-inspired robot that digs into underwater soil efficiently by expanding and contracting its valves to fluidize the substrate around it, thus reducing drag. This technology has potential applications in fields such as anchoring, sensor placement, and cable installation. Though there are similar potential applications in dry soil, the lack of water to advect the soil particles prevents fluidization from occurring. However, theoretically, if the RoboClam contracts quickly enough, it will achieve a zero-stress state that will allow it to dig into dry soil with very little drag, independent of depth. This paper presents a theoretical model of the two modes of soil collapse to determine how quickly a device would need to contract to achieve this zero-stress state. It was found that a contraction time of 0.02 seconds would suffice for most soils, which is an achievable timescale for a RoboClam-like device.Massachusetts Institute of Technology. Department of Mechanical Engineerin

Feature Improvement and Cost Reduction of Baitcasting Fishing Reels for Emerging Markets

Baitcasting fishing reels are a challenging product to sell to new users in emerging markets. Their complex and less-than-intuitive design make them poor candidates for a novice fisherman selecting his or her first fishing reel. Based upon manufacturer constraints and design requirements, our team lowered the price point and improved the usability of the Okuma Cerros baitcasting fishing reel to make it more appealing to a wider range of consumers, especially in emerging markets. This project resulted in a three-phase redesign: reducing cost via alternative materials and replacing bearings with bushings; prototyping a simplified cast control system; and proposing an improved user interface

An investigation of the critical timescales needed for digging in wet and dry soil using a biomimetic burrowing robot

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.Cataloged from PDF version of thesis.Includes bibliographical references (pages 43-46).The Atlantic razor clam, Ensis directus, burrows underwater by expanding and contracting its valves to fluidize the surrounding soil. Its digging method uses an order of magnitude less energy than would be needed to push the clam directly into soil, which could be useful in engineering applications such as anchoring and sensor placement. The first chapter of this thesis presents the theoretical basis for the timescales necessary to achieve such efficient digging and gives design parameters for a device to validate the timescales. It then uses RoboClam, a robot designed to imitate the razor clam's movements, to test the design rules. It was found that the minimum contraction time is the most critical timescale for efficient digging, and that efficient expansion times vary more widely. The results of this chapter can be used as design rules for other robot architectures for efficient digging, optimized for the size scale and soil type of the specific application. The second chapter of this thesis examines whether it would be theoretically possible to use the same E. directus-inspired method to dig into dry soil, for applications such as sensor placement. The stress state of the soil around the robot was analyzed, and a target stress state for dry soil digging was found. Then, the two possible modes of soil collapse were investigated and used to determine how quickly the robot would have to contract to achieve the target stress state. It was found that for most dry soils, a RoboClam-like device would have to contract in 0.02 seconds, a speed slightly faster than the current robot is capable of, but still within the realm of possibility for a similar machine. These results suggest that the biomimetic approach successfully used by RoboClam to dig into submerged soil could feasibly be used to dig into dry soil as well.by Monica Isava.S.M

An Experimental Investigation of Digging Via Localized Fluidization, Tested With RoboClam: A Robot Inspired by Atlantic Razor Clams

The Atlantic razor clam, Ensis directus, burrows underwater by expanding and contracting its valves to fluidize the surrounding soil. Its digging method uses an order of magnitude less energy than would be needed to push the clam directly into soil, which could be useful in applications such as anchoring and sensor placement. This paper presents the theoretical basis for the timescales necessary to achieve such efficient digging and gives design parameters for a device to move at these timescales. It then uses RoboClam, a robot designed to imitate the razor clam's movements, to test the design rules. It was found that the minimum contraction time is the most critical timescale for efficient digging and that efficient expansion times vary more widely. The results of this paper can be used as design rules for other robot architectures for efficient digging, optimized for the size scale and soil type of the application