User:Magicmon98/sandbox/Octobot

The Octobot is a soft-bodied autonomous robot designed and created by Harvard University experts and researchers on soft robotics. Through embedded 3D printing (EMB3D) and soft lithography, it is the first soft robot, made of silicone rubber, that is untethered. It runs solely on the decomposition of hydrogen peroxide as fuel. Measuring at 2.5 inches and weighing 0.2 ounces, its function is to move its arms. The Octobot demonstrates that robots can operate using only soft materials. The Harvard University researchers hope to use the Octobot for tasks that hard-bodied robots cannot do and that are safer for humans.

Design

A microfluidic soft controller is pre-fabricated and placed into a mould of the Octobot. The mold takes the shape of a small octopus, inspired by its lack of an endoskeleton. Silicone polymers are then placed over the mould. Fugitive and catalytic inks are 3-D printed onto the mould. The catalytic ink contains platinum particles. The fugitive ink must be removed or evacuated so as to allow for hollow channels and networks inside of the Octobot. To achieve this, the mold is heated at a temperature of 90°C. The process evacuates any remaining fugitive ink. Fluorescent dyes were added to the Octobot to help with the visualization of the system's internal features.

Control logic

The Octobot's logical engine, or the soft controller, is about one millimeter thick. It takes the appearance of a silicon wafer. On top of this are the 3-D printed channels that are connected into a circuit, similar to an electronic circuit board. The control logic is composed of four sections: upstream (liquid fuel storage), oscillator (liquid fuel regulation), reaction chamber (decomposition into pressurized gas) and downstream (gas distribution for actuation and venting). The control logic's main function is to control when the fuel will be released into the rest of the system's networks.

Upstream

The fuel that is used for the system to operate is 50% hydrogen peroxide. Using a syringe pump, 0.5 mL of fuel is injected into each of the two fuel reservoirs located inside of the control logic. The reservoirs expand after injection, releasing fuel into the soft controller through the oscillator. Each reservoir has its own network for the fuel to flow. Check valves are used to prevent the fuel from coming back into the fuel inlets.

Oscillator

The oscillator includes a system of pinch valves and downstream check valves. After fuel injection, the pressurized fuel inflow turns into alternating flow outflow through the process of pinch valves. As one channel is closed, the other one opens and fuel is then released into the reaction chambers where hydrogen peroxide will decompose.

Reaction chamber

Within the reaction chamber are platinum particles. The platinum serves as a catalyst to decompose hydrogen peroxide into water and pressurized oxygen gas. The gas' volumetric expansion will be about 160 times its original volume. The gas then flows downstream into the actuators and vents. The actuators are located within the tentacles of the Octobot.

Downstream

The resulting pressurized oxygen gas, which is prevented from returning to the soft controller via downstream check valves, flows into one of the downstream networks consisting of four actuators and one orifice, or opening. Pressure from the gas will displace the actuators and leave the system through the vent orifices as exhaust. Because each reservoir is only connected to four actuators, only four arms move at a time. The alternating flow of fuel through the process of pinch valves and control logic's directions will keep the alternating process going until all fuel is decomposed. For a sharp and strong actuation and timely venting, a balance must be reached between supply gas flow, actuation pressure, and exhaust rate.

Functions

The hydrogen peroxide reacts with a platinum catalyst to inflate the tentacles and displace them. Because the Octobot is an early proof-of-concept design, its only function is to move its tentacles through the chemical reactions. The microfluidic network is designed to feed back on itself, shutting down flow of one side of the fuel networks and opening the other side in a predetermined sequence. The Octobot currently runs for up to 8 minutes on 1 milliliter of fuel.

Appearance

The Octobot measures at 2.5 inches (6.5 centimeters) long and wide and weighs 0.2 ounces (6 grams). It has no rigid structure and is made of silicone with elastic legs to allow the tentacles to move. The appearance was inspired by the shape of the mold that the soft controller was placed in. The shape of the Octobot mimics that of an octopus that has no rigid components within its body.

Future Developments

Because the Octobot is a fairly new concept, its only ability is to wave its arms. However, the Harvard team hopes to design an Octobot that can crawl, swim, and interact with its environment. The researchers are now working to add sensors to the robot, which would allow it to detect objects in its environment and navigate toward or away from them. The Octobot's design can be scaled up or down to a much greater size, or an even smaller one. This can increase or decrease fuel capacity depending on the robot’s function.

Soft robots such as the Octobot can serve to perform tasks that rigid, hard-bodied robots are not capable of doing. According to Michael Wehner, one of the project researchers, the replacement will make the task either easier or safer for humans. Wehner goes on to explain, "[It could] either handle something that's very delicate, or move the body around to get into tight spaces in search and rescue, or maybe internal medicine." As soft robotics continues to advance, scientists and researchers hope to use these robots for marine search-and-rescue missions, oceanic temperature sensing, and military surveillance.

External links

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