• Create a new jellyfish that uses the hydraulic pump
• Wire and test it in the fish tank

Summary of week progress

We modified the existing jellyfish design to take input from the hydraulic pumps rather than a hand pump/syringe. Each of the three pumps controls a tentacle. Since the mold is larger than the print bed of the stratasys printers, we attempted to use the Ultimakers in Hunt. However, after sending the STL files to Cody, two of the same parts were accidentally printed so we were unable to pour the mold.

We also filled the aquarium tank and tested the current pump. It’s able to generate a pretty significant circular current.

Objectives for this week

• print the mold for the 3x hydraulic pump jellyfish and pour
• bond and wire the pumps and test
• debug inevitable issues

Joints

Upper Arm Half

Lower Arm Half

Wire Retaining Disk

Mold

Results

Full Assembly

Wire Retainer

Joints

Silicone Arm

Volume: 5176.03 mm^3

Estimated Mass (EcoFlex 00-30): 5.4g

Solidworks Files zip folder: https://drive.google.com/file/d/1utghJZBrgKTksT-dKjwnOcxXw6yIsabk/view?usp=sharing

STLs zip file: https://drive.google.com/file/d/1ur0FPme_Rb3QgO5giWpFPWsS3l0zE7w1/view?usp=sharing

Results

unfortunately the small segments were lost in the solvent bath, I didn’t have a working prototype. Additionally, the hole of the wire retainer piece was too small and was filled in by the print material, so a wire was unable to be inserted.

This will hopefully be a radial tentacle thing

Part

Bottom Mold

Top Mold

note: these are sldprt files because WordPress didn’t allow stl upload

referenced files

Design II

Results

Creative Requirements

• Multiple soft creatures in the aquarium (3-5)
• Some level of controllable motion
• Interaction between the soft robots within the environment

Critical Path

• Desired behavior chosen
• General form determined
• Actuation method determined
• Actuator, power, logic housing
• design in CAD
• 3D print of housing
• Mold fabrication and soft component fabrication
• Assembly
• Structural acceptance test
• Programming
• Tank construction
• Motion acceptance test

Proof of Concept

The first proof of a concept would be an unintegrated system that can produce the desired actuation which would allow the robot to catch the current in the tank. This would require a molded silicone part from a 3D printed mold, servo or other actuator with basic logic, and the basic mechanical mechanism for translating the servo motion to the radial open/close motion desired. With a working proof of concept, work can then be done on integration, packaging, waterproofing, and programming.

Resources

L. Hines, K. Petersen, G. Z. Lum, and M. Sitti, “Soft Actuators for Small-Scale Robotics,” Advanced Materials, vol. 29, no. 13, p. 1603483, 2017, doi: 10.1002/adma.201603483.

Y. Zhou, H. Jin, C. Liu, E. Dong, M. Xu and J. Yang, “A novel biomimetic jellyfish robot based on a soft and smart modular structure (SMS),” 2016 IEEE International Conference on Robotics and Biomimetics (ROBIO), 2016, pp. 708-713, doi: 10.1109/ROBIO.2016.7866406.

My project idea is an aquarium exhibit with small soft robotic fish or other creatures which can interact with each other in some way. The actuation methods for each robot will be simple for feasibility. Possible creatures include: fish with soft tails which can actuate to swim, or jellyfish with soft robotic tentacles. The creatures should have some mechanism to interact with each other, either directly with proximity sensors, or (more likely) a magnet to divert them from each other. The overall goal is to create a robotic “ecosystem”, possibly with “predator” and “prey” fish.

Art/Design Resources

https://www.csail.mit.edu/research/sofi-soft-robotic-fish

https://spectrum.ieee.org/blueswarm-robotic-fish#toggle-gdpr

Technical/Research Papers

Jennifer Frame, Nick Lopez, Oscar Curet, and Erik D. Engeberg. Thrust force characterization of free-swimming soft robotic jellyfish. Bioinspiration and Biomimetics, 2018. doi:10.1088/1748-3190/aadcb3

J. E. M. Teoh, R. C. Mysa, T. V. Truong, and P. V. y Alvarado, “Propulsive performance of an undulating fin soft robot,” in Global Oceans 2020: Singapore – U.S. Gulf Coast, Oct. 2020, pp. 1–5. doi: 10.1109/IEEECONF38699.2020.9389238.

L. Hines, K. Petersen, G. Z. Lum, and M. Sitti, “Soft Actuators for Small-Scale Robotics,” Advanced Materials, vol. 29, no. 13, p. 1603483, 2017, doi: 10.1002/adma.201603483.

Y. Jiang, X. Liu, H. Chen, W. Gong, Y. Lu and W. Zhang, “Design and Modeling of a Biomimetic Wire-driven Soft Robotic Fish,” 2019 Chinese Automation Congress (CAC), 2019, pp. 1778-1782, doi: 10.1109/CAC48633.2019.8996663.

For my informal research, I started with an Instagram account I follow which highlights the works of various student and professional designers.

https://www.instagram.com/design_burger/?hl=en

However, this page mostly focused on product design, so I went to the accounts that design_burger was following to find some other sources for research. I then found the account of a Los Angeles based design studio called Estudio Persona

https://www.estudiopersona.com/

https://www.instagram.com/estudiopersona/?hl=en

When looking through their website and collections, I saw this bench (white on right of image). The bench is CNC’d foam and upholstered fabric, so it is probably quite rigid. From the description of the product:

“A playful exaggeration of the circle is rendered in a cartoon like bench, overstuffed and pushed to the limits, while simultaneously exploring the depths that can be created while circular forms flow inward and fall into themselves. Smooth white upholstery suggests the liquid flow of air in constant movement.”

From the description, I believe the designer was aiming to convey softness and movement in an object that is rigid or static at the least. The round shape and receding curves into the two holes seem to invite the user into it.

Alternative Expressions with Soft Technologies

I believe the soft and inviting nature of this bench can be conveyed even more effectively by utilizing soft technology. The bench could conform to the user who is laying or sitting on it, and could even rise and fall slightly as if breathing. This would evoke a natural comfort. The bench could also actuate similar to the soft silicone arms we have seen in class so that the angle of the bench could increase for a user laying or sitting on it, to provide back support.

I imagine an entire room of soft kinetic furniture, which is breathing as if the room was an organism, similar to the Zerg in Starcraft, but less frightening.

Research: Soft curvature sensors for joint angle proprioception

R. K. Kramer, C. Majidi, R. Sahai and R. J. Wood, “Soft curvature sensors for joint angle proprioception,” 2011 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2011, pp. 1919-1926, doi: 10.1109/IROS.2011.6094701.

This paper describes a soft sensor composed of a thin elastomer film with liquid metal channels and a sensing element inside. When the curvature of the sensor changes, the liquid metal exerts pressure on a mirco-channel, which is sensitive to changes in cross-sectional area. The change in cross-sectional area corresponds to a change in electrical resistance.

This technology could be used to sense the user’s interaction with the bench; as the user sits or lays down, the curvature sensors would be able to sense the shape of the person’s body and adapt the shape of the bench accordingly. The benefit of using these soft sensors is that it would not disrupt the soft nature of the bench as a traditional sensor would. In general this sensor enables interactive and fully soft art, ranging from displays to reactive wearable garments.

https://pulitzerarts.org/feature/claes-oldenburg-ice-bag-scale-b-1971/

I also found a kinetic sculpture which uses rigid parts, but gives the illusion of soft movement.

I continued searching for soft kinetic sculptures from these two sites, but had trouble finding any art from soft mediums.

I was interested in the idea of soft architecture, when researching this topic I found this project for a soft transforming pavillion:

Furl: Soft Pneumatic Pavilion

The pneumatic tentacles raise and lower according to environmental conditions.

Ming Luo, Mahdi Agheli, and Cagdas D. Onal. Soft Robotics.Jun 2014.136-146. http://doi.org/10.1089/soro.2013.0011

This paper presents a solution to a novel problem problem for soft robotics: the theoretical modeling of motion, which is much more difficult compared to rigid body robotics. A soft model snake-type robot is simulated and the theoretical model results are validated against experimental data.

Considerations (from the publisher’s reviewer’s guide)

Is the research original, clearly explained, and supported?

Based on the citations and description of the work done, the research seems original. The paper builds upon previous methods to theoretically describe the motion of rigid-body snake robots and iterative models of soft-body snake robots.

Is the data complete, accurate, and easily accessible?

• The data seems generally complete, and the paper mentions the parameter sets that were not validated through the prototype due to design restrictions.

• The data is accurate as far as I can tell and proper general statistical practices are used when making conclusions from data.

• The data presented in the paper is described clearly and presented accessibly.

Are the figures and tables, clear, readable, and support the conclusions of the manuscript?

The figures and tables are presented clearly and support the conclusion that the theoretical dynamic model is accurate against experimental results.

Are the methods and protocols clearly defined?

• The derivation of the equations of motion are very clearly defined.

• The manufacturing methods of the soft body components are well defined, but the paper lacks

• detailed description of the other components of the prototype.

• The paper does not mention possible inaccuracies due to the experimental set up (pressure lines friction, tension, head loss).

• Protocols for the experimental tests and methods for their comparison against the computational model are well defined.

Is supporting data included in manuscript, as supplementary material, or via a link to a repository?

Supplementary data is not provided, although this may be due to limitations of the publishing site.

Ethics: Are there any obvious ethics issues? Are appropriate approvals and ethics protocols stated in the manuscript? Are there any concerns about plagiarism, or data or image manipulation?

• The research itself does not present any clear ethics issues.

• plagiarism, data, or image manipulation does not appear to be present in the paper.

Are the citations complete and relevant?

The paper contains relevant citations for its descriptions of previous work on the subjects it covers.

Referee Form

Do you have any conflict of interest in reviewing this paper?

No.

Expertise. Provide your expertise in the topic area of this paper.

2 – Passing Knowledge

Summary. Please summarize what you believe are the paper’s main contributions to the field of soft robotics.

The paper addresses the present difficulty of dynamic modeling in the field of soft robotics. Since compliant bodies have theoretically infinite degrees of freedom, analytical models for soft-bodies robots are considerably more complex than that of rigid-bodied robots. The paper presents a complete dynamic model for a soft-jointed snake-like robot with rigid links, assuming constant curvature of the joints computed by the angles of the links. The system of equations for the motion of the snake is derived and a link curvature based control scheme is presented. The dynamic model is then validated against a prototype soft-body snake robot.

Strengths and Weaknesses. What are the main strengths and weaknesses of this work? Does the paper have strengths in originality and novelty?

The main strength of the paper is its completeness in the derivation of the dynamic model, and high level accuracy when compared to the prototype. The paper also builds off a previous paper by the same authors, where the fundamental constant curvature approach was used to give “general intuition” about the soft snake robot’s movement. The dynamic model is also compatible with existing rigid snake-like robots.

One weakness of the paper is that is does not fully describe the manufacturing process of the prototype, and does not describe the design limitations that may cause disagreement with the model, especially in the lower level parameters such as the position of the center of mass. The paper also does not provide supplemental resources such as supporting data or a repository.

Soundness. Are the ideas, algorithms, results or studies technologically/methodologically sound?

The primary purpose of the research is to present a complete dynamic model for a soft-bodied snake-like robot, and validate it against an experimental prototype. This purpose is completed via a thorough derivation of the model. The results are also clearly presented and shortcomings and relevant assumptions are noted.

Related Work. Does the paper adequately describe related and prior work?

The introduction of the paper adequately describes related and prior work.

Presentation. Is the paper well organized, well written and clearly presented?

The paper is well organized and written with the exception of a few seemingly missing equations in the derivation of the dynamic model.

Suggestions. Do you have suggestions for improving this paper?

One suggestion is to normalize figure sizes. For a paper published online this is not as much of an issue. Another suggestion would be to compare other researcher’s models for soft or hybrid snake robots to the one presented, or to acknowledge the achievements and shortcomings of other models.

Comments to Committee (Hidden from authors). Does the paper have enough originality and importance to merit publication? Is the paper relevant to the field? These comments will NOT be sent to the authors:

This paper seems to present a solution to a relevant problem in the field of soft robotics. Based on the previous work and citations, the work seems original.

Overall Rating. Provide your overall rating of the paper (5 is best)

4 – Probably accept: I would argue for accepting this paper.

M. Luo, M. Agheli, and C. D. Onal, “Theoretical Modeling and Experimental Analysis of a Pressure-Operated Soft Robotic Snake,” Soft Robotics, vol. 1, no. 2, pp. 136–146, Jun. 2014, doi: 10.1089/soro.2013.0011.

This paper was found in the Survey Paper references. It describes a novel method to model the dynamics of a soft robotic snake.

Root Paper: A Modular Approach to Soft Robots

C. D. Onal and D. Rus, “A modular approach to soft robots,” in 2012 4th IEEE RAS EMBS International Conference on Biomedical Robotics and Biomechatronics (BioRob), Jun. 2012, pp. 1038–1045. doi: 10.1109/BioRob.2012.6290290.

From the source paper, I was looking for a paper that described some of the general design principles for a snake-like soft robot. This paper presents a method to link segments of elastomeric actuation elements. The segments are actuated via pressurized fluid. A snake-like soft robot is presented, representing a series configuration of the elastomeric elements, and a rolling soft robot is shown as an example of a parallel configuration. Hybrid configurations are also discussed with general equations to determine the overall motion

Lateral Paper 1: Design, Kinematics, and Application of Axially and Radially Expandable Modular Soft Pneumatic Actuators

N. Wang, B. Chen, X. Ge, X. Zhang, and W. Chen, “Design, Kinematics, and Application of Axially and Radially Expandable Modular Soft Pneumatic Actuators,” Journal of Mechanisms and Robotics, vol. 13, no. 2, Mar. 2021, doi: 10.1115/1.4049973.

This paper expands on the root paper by presenting an application of the elastomeric actuation elements. By constraining the expansion of the elements either radially or axially, different motions can be generated. The paper shows prototypes for biped and quadruped soft robots which can crawl along the insides of tubes with uneven surfaces and curvature. Kinematic models for the actuators are also defined and compared to experimental results.

Lateral Paper 2: Gait and Locomotion Analysis of a Soft-hybrid Multi-legged Modular Miniature Robot

N. Mahkam and O. Özcan, “Gait and locomotion analysis of a soft-hybrid multi-legged modular miniature robot,” Bioinspir. Biomim., vol. 16, no. 6, p. 066009, Sep. 2021, doi: 10.1088/1748-3190/ac245e.

This paper discusses the current problem in the soft robotics field that the performance of miniature soft robots is often far below that of similarly sized creatures in nature (ie insects). The paper describes the design and analysis of a multi-legged modular miniature robot with soft backbone connectors and rigid legs with compliant joints. Based on the compliance of the legs, backbone connectors, and number of modules, the optimum gait cycle for the robot is determined.

This paper is related to the root paper as it describes an application of modular soft robotic actuators.