Developing a Soft Robot Inspired by Octopuses for Efficient Ladder Climbing

Student: Zirui Wang
Table: ENG4
Experimentation location: School, Home
Regulated Research (Form 1c): No
Project continuation (Form 7): No

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  1.  Margheri, L., Laschi, C., & Mazzolai, B. (2012). Soft robotic arm inspired by the octopus: I. From biological functions to artificial requirements. Bioinspiration & Biomimetics, 7(2), 025004.
  2. Mazzolai, B., Margheri, L., Cianchetti, M., Dario, P., & Laschi, C. (2012). Soft-robotic arm inspired by the octopus: II. From artificial requirements to innovative technological solutions. Bioinspiration & Biomimetics, 7(2), 025005.
  3. Iida, F., & Laschi, C. (2011). Soft Robotics: Challenges and Perspectives. Procedia Computer Science, 7, 99–102.
  4. Cianchetti, M., Arienti, A., Follador, M., Mazzolai, B., Dario, P., & Laschi, C. (2011). Design concept and validation of a robotic arm inspired by the octopus. Materials Science and Engineering: C, 31(6), 1230–1239.
  5. ‌Calisti, M., Corucci, F., Arienti, A., & Laschi, C. (2015). Dynamics of underwater legged locomotion: modeling and experiments on an octopus-inspired robot. Bioinspiration & Biomimetics, 10(4), 046012.


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Research Plan:


From the summer till March, this project will study the motion of octopuses through other available research and materials. Then, based on these ideas, a soft robot arm will be produced and connected to motors, capable of climbing ladders independently and grabbing certain objects. I will build this robot with soft arms and Arduino motors that can bend the arms repeatedly so that it can climb ladders.


In this time span, there are several engineering goals to reach. First, I need to design a fully functional chassis that can hold different Arduino pieces as well as other arm components. This can be done through the use of CAD software such as AutoCAD and Solid Work. This software will allow me to custom-build 3D structures and print materials that can be used for chassis and molds for the arm (if applicable).


As a technological product, it will undergo a series of tests to ensure its functionality and reliability. To effectively achieve this, I aim to first build a prototype that could be tested for its performance and deficiencies and improve upon that. The main goal of this project is reliability, accuracy, and low cost. Therefore, this project will be tested with these three criteria in mind, and every component used to build this robot will be available online and relatively inexpensive.


Questions and Answers

1. What was the major objective of your project and what was your plan to achieve it? 

       a. Was that goal the result of any specific situation, experience, or problem you encountered?  

The goal I set for this project is actually from a documentary I watched. The documentary described the octopus’s ability to control its arms without any issues naturally and it is incredibly strong as well as flexible. This interests me, and this idea has become the goal of this project. However, due to constraints, the goal of the project is limited to only climbing ladders instead of a multifunctional soft arm.


       b. Were you trying to solve a problem, answer a question, or test a hypothesis?

I was trying to produce a product based on the original goal: using soft robotics to climb ladders and grab objects. This product also solves a problem where climbing ladders with hard robots is incredibly hard. Besides, this project can also be extended into more advanced robotics with advanced technologies. For example, it could be used for extreme environments where robots can only go through tiny cracks, like after an earthquake. In this scenario, it will be incredibly hard to do with hard robots, while soft robots can easily navigate themselves due to their flexible nature. 



2. What were the major tasks you had to perform in order to complete your project?

       a. For teams, describe what each member worked on.

Some major tasks that I have to perform in order to complete this project include the chassis design, arm design, Arduino hardware and programming. All of these components need to work well individually and in a compact robot. 



3. What is new or novel about your project?

       a. Is there some aspect of your project's objective, or how you achieved it that you haven't done before?

Some special aspects of this project include the designing of soft arms, a control scheme for the arms, as well of using different Arduino components. I’ve never done these before and during the development of this project, I naturally came into contact with all of them. For example, when designing components. I was first introduced to CAD software. I learned the fundamental of CAD as well as more advanced stuff. Besides, I learned a lot regarding soft materials. There are different types of rubber with different stiffness as well as 3D printable, flexible material that’s much stiffer than these rubber and much lighter.


After designing and printing these components, I started with Arduino. The is a popular programming language that resembles many similarities to C++ and Java, which I know well. From learning to program different components of a basic Arduino part to more advanced control for motors and servos. Besides simply programming knowledge, I also learned about hardware. For example, how to control different motors, LEDs, servos, and angle sensors. These components are all extremely important to this project and it’s all very new to me. This is extremely interesting from the start to the end.


       b. Is your project's objective, or the way you implemented it, different from anything you have seen?


This project has developed in the same way as predicted initially, with several design changes that only benefit the robot.


First, the material for the chassis evolved through time. At first, it was laser-printed wood. Then, the second prototype was changed to a 3D-printed chassis. On paper, this provided a lot of benefits, such as better compartments for motors and other components. However, it’s heavy and printing fails from time to time. Therefore, in the final design, the design shifted back to laser-cut plywood. The final design has a lighter weight than both of the previous versions. It also includes compartments for the motors and places to mount other Arduino pieces.


Secondly, the arm design had a massive shift from the second prototype to the final product. I changed the arm material design from rubber to a 3D-printable flexible material. This is due to two reasons. First of all, the rubber had too much flex that it would bend from side to side, which is bad. Secondly, the rubber arm is too heavy for the robot to carry, putting extra strain on the motors. Therefore, shifting to a lighter, slightly less flexible material is logical. This benefited the robot a lot and the testing became much smoother.


Finally, there are changes regarding the components of the robot. At the beginning, the robot is constructed out of plain Arduino components with an Uno mainboard. They are good for the first prototype, but they are both heavy and big. Therefore, I shifted to a smaller Arduino mainboard and changed to a small design on the control of the string.



       c. If you believe your work to be unique in some way, what research have you done to confirm that it is?


This project is unique in certain ways but similar to other projects. It’s similar to other projects as it uses mostly the same material and components while having the same ideas. However, the way that this project achieves the goal is unique. The idea of using the contraction of a string to pull the soft arm with several joints is unique. Unlike many other research types that either use air or multiple strings to achieve this goal, this project only uses one. However, the drawback is that the robot arm can only be bent and extended in a fixed manner. Some work that I’ve put in to make sure that this part of the project is unique is through searching through the internet. I searched through hundreds of research in google scholar and none of the research that showed up resembled similarities.



4. What was the most challenging part of completing your project?

      a. What problems did you encounter, and how did you overcome them?


There are a lot of problems that I’ve encountered and overcome. First of all, motor choices are quite scarce. For this project, motors need to be both strong and small at the same time. This is can achieve through increasing torque and sacrificing speed. Besides, the motor’s output axis needs to be perpendicular to its main body so it can easily fit into the robot and make it slimmer. However, finding such a motor isn’t easy. I’ve tried a few and only the last one worked out.


Besides, programming this robot is also difficult. Since the robot needs to receive user input, respond, and continue previous tasks, the program needs to be a special structure. Since Arduino doesn’t support multi-thread, I have to create a way where a main loop will take place, and every control with take place inside that loop. This ensures that every command will be run and multiple tasks can be run at the same time. It took me time to figure out the solution to this problem, but it worked out really well in the end.



      b. What did you learn from overcoming these problems?


From overcoming these problems, I’ve learned a lot of valuable skills. First of all, I’ve learned more about Arduino and its functionalities. I’ve built up more practical programming skills, which teaches me a lot about bypassing problems with currently available information and certain constraints.


Secondly, I learned to find more available resources online and problem-solving skills. For example, when solving a unique problem, it could be broken down into pieces and dealt with one by one. Afterward, it will be assembled together to form a solution to the big problem.



5. If you were going to do this project again, are there any things you would you do differently the next time?


Next time, I would rather use more material to expand the purpose of this project. Instead of limiting its use to climbing a specific type of ladder, it could also be used for other purposes, such as controlling a controller, holding objects, etc. Despite the fact that this would dramatically increase the difficulty of this research, with my problem-solving skills and knowledge of CAD and Arduino, I believe I could handle this.


Besides, the testing of this project could be more thorough, for example, instead of testing only one type of ladder and measuring its forces. It could also be tested on its extremities. For example, what is the heaviest weight that it can possibly handle.


Finally, the start and design of this project could be improved. At the beginning of this project, it was poorly thought out. Some of the ideas on specific parts of the robot are still obscure the overall construction isn’t planned as well. If it could be restarted, I would spend more time on the design and planning of the first and from there on, changes could be made fast and it could be better.



6. Did working on this project give you any ideas for other projects? 


There is a lot of expandability to this project and future implementations. One such future implementation of this project is in outer space. One such soft arm can be extremely helpful when astronauts are in outer space while not in a spaceship. With some redesign of the first part, it can grab a lot of things so that the astronauts can focus on their work. Besides, since the arm is malleable, it could grab the astronauts so they don’t flow away too far. Also, it can help astronauts go to places they want to go outside the spaceship. Such advantages are very achievable with soft robotics, while traditional robotics is more complicated.



7. How did COVID-19 affect the completion of your project?


Covid-19 hadn’t impacted this project massively but did delay the advancement of this project slightly. For example, some parts of the project aren’t available online. Besides, I could only work in several places and had limited access to 3D and laser printers. These delayed the development of this project a lot. Until the covid restriction has lifted and it’s more accessible afterward.