Make a Robotic Balloon Muscle
30-60 min
Ages 8+
What Will You Make?
If you’ve seen the Disney hit Big Hero 6 and its star Baymax, you know that soft, inflatable robots are all the rage. Inflatable robots and robotic parts are cheap, lightweight, strong, and collapsible, making them easy to store or carry. And inflatable air muscles allow robots to move in a more natural way than gears and motors.
This project is based on a twisty balloon air muscle created by a Brigham Young University mechanical engineering student named Wyatt Felt, and adds a few twists of its own. It opens and closes a Sarrus linkage, a pair of hinges set at right angles to one another, and includes a built-in release valve mechanism. It’s easy to put together and great for showing kids (or adults) how air pressure can be used to actuate robot parts.
The Robotic Balloon Muscle project is adapted from Kathy Ceceri’s new book Making Simple Robots: 2nd Edition published by Maker Media.
What Will You Learn?
This build doesn’t require anything fancy. Just make sure you have extra balloons on hand — they tend to pop!
You will learn to blow up, twist and tie balloons as you explore pneumatics — a branch of engineering that makes use of gas or pressurized air.
Blow Up Two Balloons
Step 1
Use the hand pump to inflate two balloons, leaving about 4 to 5 inches (10 to 12 cm) uniflated at the end. This is known as the tip of the balloon.
Helpful hint: Before inflating a balloon, stretch it lengthwise a few times.
Step 2
Remove the pump and let out a little air (known in the business as burping the balloon). This bit of slack makes it easier to twist the balloon without popping it. Tie the neck of the balloon in a knot to seal it.
Make a Hinge in Each Balloon
Step 1
To make a hinge in the first balloon, bend it in half. At the bend, pinch a golf-ball-sized segment in your fingers.
Step 2
Twist it around three times, spinning it like a dial. Then circle it around the balloon itself until it reaches its starting point.
Step 3
The hinge should look like a knee sticking out in front. Do the same with the other balloon.
Tie the Tips of the Balloons Together and Insert the Tubing
Step 1
Tie the tips of the balloons together using the uninflated extra rubber. Tie another knot about half an inch (1 cm) above the first. The balloons will form a diamond shape with the hinges in the middle.
Step 2
Now take the 10-inch (25 cm) piece of plastic tubing and the scissors or an art knife. Make a release valve in the tubing by cutting a small slit about halfway down. Don’t let it go more than partway through the tubing. You should be able to bend the tubing back to open the slit without tearing the tubing.
Take a piece of electrical tape about 2 inches (5 cm) long, and fold over a tiny bit at one end. Take the other end and wrap it around the tubing so it covers the slit. Use the folded-over end as a tab that you can pull back to reveal the slit.
Step 3
Take a piece of electrical tape about 2 inches (5 cm) long, and fold over a tiny bit at one end. Take the other end and wrap it around the tubing so it covers the slit. Use the folded-over end as a tab that you can pull back to reveal the slit.
Step 4
Try bending the tubing back so the slit opens up. Then reseal it with the tape. You can test it by inserting the air pump to make sure it is airtight when sealed.
Step 5
Poke one end of the tubing through the gap between the two knots in you tied with the balloon tips.
Add the Balloon Muscle to the Linkage
Step 1
Take a third balloon, inflate it, then let the air out. This is your air muscle. Pull the opening of the air muscle balloon over the end of the tubing that pokes out between the knots. The balloon should cover about 1 inch (2 cm) of the tubing. Secure the balloon to the tubing with a piece of electrical tape.
Step 2
Take the top and the bottom of the balloon diamond and press them towards each other. This is the movement your inflatable hinge will make. Decide how close you would like them to get, and tie the tip of the air muscle balloon to the tips of the other two balloons to hold them in this position.
Step 3
Insert the end of the air pump into the other end of the clear tubing, as far as it will go. Secure it with more electrical tape if needed.
Step 4
Use the pump to slowly and carefully inflate the muscle balloon. As it fills with air, it should lengthen and push the balloon hinge open. To let the hinge close up again, open the release valve by unwinding the tape enough to expose the slit, and bending the tubing back to widen the opening. The air should escape and the balloon return to roughly the same length as when it started.
Troubleshooting: If you’re having trouble inflating the balloon, test out your pump on another balloon fresh out of the package. Cheap pumps break easily. Also check your balloon for leaks.
What Is Happening Here?
About Inflatable Robots
Considering they started as blow-up beach toys, inflatable robots are a lot more useful than you might think! Inflatable robots (and robotic parts) are cheap, lightweight, and collapsible. They’re easy to store and carry around. Plus, inflatable muscles let robots move in a more natural way than gears and motors. No wonder Disney’s animated hit Big Hero 6 featured a friendly inflatable robot named Baymax, a giant blow-up home health aide that fit inside a suitcase when not busy working.
Real inflatable robots come with different types of “skin.” Small and squishy robot grippers and crawlers are made of rubber-y, stretchy material. Larger inflatable robots are often made of stiff material, like a bounce house-style trampoline. Inside, all inflatable robots have one or more chambers that can be filled with air or fluid. To make the robot bend or change shape, pumps move the air around to fill or empty different chambers.
Inflatable robots can be surprisingly strong. The huge walking inflatable Pneubotics created by Saul Griffith’s research and design center Otherlab in California in 2011 looked like very odd horses or elephants and were big enough for several adults to ride on at the same time.
The inflatable robot “elbow” you will be building here was inspired by a type of exoskeleton device called an air muscle. An exoskeleton is like a robot that you wear. It helps you move more easily and can even give you super strength. In the 1950s, a nuclear physicist named Joseph Laws McKibben invented air muscles to help people like his daughter, who lost some of her ability to move when she caught a virus called polio.
Most air muscles use rubber tubing. The version you’ll build is based on a project created by an engineering student named Wyatt Felt. He built a prototype using ordinary twisty balloons — the kind used to make balloon animals. (Felt went on to earn a Ph.D., partner with Pneubotics on another inflatable project, and win several soft robotics awards.) While Felt’s model used a programmable air pump to fill and empty the balloons, you’ll use a regular hand pump and create a valve to let the air out.
The Twisty Balloon Pneumatic Actuator
Explore Wyatt Felt’s original Twisty Balloon Pneumatic Actuator on Instructables. His version uses an Arduino to control an acrylic robot with balloon “muscles.”
What Is Next?
More to Explore
- You can expand on your Robotic Balloon Muscle by making a complete balloon robot body and create your own version of Baymax. Or go abstract and use your muscle to make a mathematical balloon model.
- Balloon twisting can be used for art and engineering! Learn some balloon design tips with these online lessons from Airigami: airigami.com/online-lessons.
- Invent your own inflatable robots using designs from math instead of nature. For example, in 2020 Stanford University researchers demonstrated inflatable tubes that could be bent using motorized corners that slid along their surface. Connecting several tubes into a pyramid created shapes that rolled along under their own power as the lengths of their sides were changed. Find out more at news.stanford. edu/2020/03/18/squishy-shape-changing-bot-roams-untethered.
- Custom-design an edible inflatable robot — see the instructions in my book BOTS! nomadpress.net/nomadpressbooks/ bots-robotics-engineering/.
About the Book
Making Simple Robots, 2nd Edition by Kathy Ceceri is based on the idea that anybody can build a robot! That includes kids, educators, parents, and anyone who didn’t make it to engineering school. If you can cut, fold, and tape a piece of paper to make a tube or a box, you can build a no-tech robotic part.
In fact, many of the models in this book are based upon real-life prototypes — working models created in research labs and companies. What’s more, if you can use the apps on your smartphone, you can quickly learn to tell robots what to do using free, online, beginner-level software like MIT’s Scratch and Microsoft MakeCode.
The projects in this book which teach you about electric circuits by making jumping origami frogs with eyes that light up when you get them ready to hop. You’ll practice designing all-terrain robot wheel-legs with free, online Tinkercad software, and you’ll create files ready for 3D printing. You’ll also learn to sew — and code — a cyborg rag doll with a blinking electronic “eye.”
Each project includes step-by-step directions and clear illustrations and photographs. Along the way, you’ll learn about the real research behind the DIY version, find shortcuts for making projects easier when needed, and get suggestions for adding to the challenge as your skill set grows.
Suggested Add-On: Making Simple Robots Starter Pack
This companion starter pack has all the electronics you’ll need and then some for the projects in Making Simple Robots, 2nd Edition, by Kathy Ceceri (book required for projects).
Materials:
- Twisting Balloons (3). Available in party goods stores.
- Balloon hand pump. An inexpensive one is fine, since you will be building this into the project.
- Clear plastic tubing, 1/4 inch (15 cm) diameter, 10 inches (25 cm) long Available in hardware stores or aquarium shops.
- Tape. Preferably electrical tape.
- Scissors
See More Projects in these topics:
Engineering Magic Physics Robotics Science STEM or STEAMSee More Projects from these themes:
Art/Craft Studio Carnival/Theme Park The Shop (Makerspace)Kathy Ceceri
Maker Camp Project Standards
Based on NGSS (Next Generation Science Standards)
CCSS (Common Core State Standards)
The Common Core is a set of high-quality academic standards in mathematics and English language arts/literacy (ELA).Measurement & Data
- Grades K-2
- CCSS.MATH.CONTENT.K.MD.A.1 Describe measurable attributes of objects, such as length or weight. Describe several measurable attributes of a single object.
- CCSS.MATH.CONTENT.1.MD.A.1 Order three objects by length; compare the lengths of two objects indirectly by using a third object.
- CCSS.MATH.CONTENT.1.MD.A.2 Express the length of an object as a whole number of length units, by laying multiple copies of a shorter object (the length unit) end to end; understand that the length measurement of an object is the number of same-size length units that span it with no gaps or overlaps.
- CCSS.MATH.CONTENT.2.MD.A.1 Measure the length of an object by selecting and using appropriate tools such as rulers, yardsticks, meter sticks, and measuring tapes.
- CCSS.MATH.CONTENT.2.MD.A.2 Measure the length of an object twice, using length units of different lengths for the two measurements; describe how the two measurements relate to the size of the unit chosen.
- CCSS.MATH.CONTENT.2.MD.A.3 Estimate lengths using units of inches, feet, centimeters, and meters.
- CCSS.MATH.CONTENT.2.MD.A.4 Measure to determine how much longer one object is than another, expressing the length difference in terms of a standard length unit.
- Grades 3-5
- CCSS.MATH.CONTENT.3.MD.B.3 Draw a scaled picture graph and a scaled bar graph to represent a data set with several categories. Solve one- and two-step "how many more" and "how many less" problems using information presented in scaled bar graphs.
- CCSS.MATH.CONTENT.4.MD.A.1 Know relative sizes of measurement units within one system of units including km, m, cm; kg, g; lb, oz.; l, ml; hr, min, sec. Within a single system of measurement, express measurements in a larger unit in terms of a smaller unit.
- CCSS.MATH.CONTENT.4.MD.C.5 Recognize angles as geometric shapes that are formed wherever two rays share a common endpoint, and understand concepts of angle measurement.
- CCSS.MATH.CONTENT.5.MD.A.1 Convert among different-sized standard measurement units within a given measurement system (e.g., convert 5 cm to 0.05 m), and use these conversions in solving multi-step, real world problems.
- CCSS.MATH.CONTENT.5.MD.C.3 Recognize volume as an attribute of solid figures and understand concepts of volume measurement.
Ratios & Proportional Relationships
- Middle School
- CCSS.MATH.CONTENT.6.RP.A.1 Understand the concept of a ratio and use ratio language to describe a ratio relationship between two quantities.
- CCSS.MATH.CONTENT.6.RP.A.3 Use ratio and rate reasoning to solve real-world and mathematical problems, e.g., by reasoning about tables of equivalent ratios, tape diagrams, double number line diagrams, or equations.
- CCSS.MATH.CONTENT.7.RP.A.1 Compute unit rates associated with ratios of fractions, including ratios of lengths, areas and other quantities measured in like or different units.
- CCSS.MATH.CONTENT.7.RP.A.2 Recognize and represent proportional relationships between quantities.
NGSS (Next Generation Science Standards)
The Next Generation Science Standards (NGSS) are K–12 science content standards.Forces and Interactions
- Grades K-2
- K-PS2-1. Plan and conduct an investigation to compare the effects of different strengths or different directions of pushes and pulls on the motion of an object.
- K-PS2-2.Analyze data to determine if a design solution works as intended to change the speed or direction of an object with a push or a pull.
- Grades 3-5
- 3-PS2-1. Plan and conduct an investigation to provide evidence of the effects of balanced and unbalanced forces on the motion of an object.
- 3-PS2-2. Make observations and/or measurements of an object’s motion to provide evidence that a pattern can be used to predict future motion.
- 3-PS2-3. Ask questions to determine cause and effect relationships of electric or magnetic interactions between two objects not in contact with each other.
- 3-PS2-4. Define a simple design problem that can be solved by applying scientific ideas about magnets.
- Middle School
- MS-PS2-1. Apply Newton’s Third Law to design a solution to a problem involving the motion of two colliding objects.
- MS-PS2-2. Plan an investigation to provide evidence that the change in an object’s motion depends on the sum of the forces on the object and the mass of the object.
- MS-PS2-3. Ask questions about data to determine the factors that affect the strength of electric and magnetic forces.
- MS-PS2-4. Construct and present arguments using evidence to support the claim that gravitational interactions are attractive and depend on the masses of interacting objects.
- MS-PS2-5. Conduct an investigation and evaluate the experimental design to provide evidence that fields exist between objects exerting forces on each other even though the objects are not in contact.
- High School
- HS-PS2-1. Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration.
- HS-PS2-2. Use mathematical representations to support the claim that the total momentum of a system of objects is conserved when there is no net force on the system.
- HS-PS2-3. Apply science and engineering ideas to design, evaluate, and refine a device that minimizes the force on a macroscopic object during a collision.
- HS-PS2-4. Use mathematical representations of Newton’s Law of Gravitation and Coulomb’s Law to describe and predict the gravitational and electrostatic forces between objects.
- HS-PS2-5. Plan and conduct an investigation to provide evidence that an electric current can produce a magnetic field and that a changing magnetic field can produce an electric current.
CCSS (Common Core State Standards)
The Common Core is a set of high-quality academic standards in mathematics and English language arts/literacy (ELA).English Language Arts Standards » Science & Technical Subjects
- Middle School
-
-
- CCSS.ELA-LITERACY.RST.6-8.1 Cite specific textual evidence to support analysis of science and technical texts.
- CCSS.ELA-LITERACY.RST.6-8.3 Follow precisely a multistep procedure when carrying out experiments, taking measurements, or performing technical tasks.
- CCSS.ELA-LITERACY.RST.6-8.4 Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 6-8 texts and topics.
- CCSS.ELA-LITERACY.RST.6-8.5 Analyze the structure an author uses to organize a text, including how the major sections contribute to the whole and to an understanding of the topic.
- CCSS.ELA-LITERACY.RST.6-8.6 Analyze the author's purpose in providing an explanation, describing a procedure, or discussing an experiment in a text.
-
- High School
-
- CCSS.ELA-LITERACY.RST.9-10.1 Cite specific textual evidence to support analysis of science and technical texts, attending to the precise details of explanations or descriptions.
- CCSS.ELA-LITERACY.RST.9-10.3 Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined in the text.
- CCSS.ELA-LITERACY.RST.9-10.4 Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 9-10 texts and topics.
- CCSS.ELA-LITERACY.RST.9-10.5 Analyze the structure of the relationships among concepts in a text, including relationships among key terms (e.g., force, friction, reaction force, energy).
- CCSS.ELA-LITERACY.RST.9-10.6 Analyze the author's purpose in providing an explanation, describing a procedure, or discussing an experiment in a text, defining the question the author seeks to address.
- CCSS.ELA-LITERACY.RST.11-12.1 Cite specific textual evidence to support analysis of science and technical texts, attending to important distinctions the author makes and to any gaps or inconsistencies in the account.
- CCSS.ELA-LITERACY.RST.11-12.3 Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks; analyze the specific results based on explanations in the text.
- CCSS.ELA-LITERACY.RST.11-12.4 Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 11-12 texts and topics.
- CCSS.ELA-LITERACY.RST.11-12.5 Analyze how the text structures information or ideas into categories or hierarchies, demonstrating understanding of the information or ideas.
- CCSS.ELA-LITERACY.RST.11-12.6 Analyze the author's purpose in providing an explanation, describing a procedure, or discussing an experiment in a text, identifying important issues that remain unresolved.
ISTE Standards (International Society for Technology in Education)
The ISTE Standards provide the competencies for learning, teaching and leading in the digital age, providing a comprehensive roadmap for the effective use of technology in schools worldwide.1.1 Empowered Learner
- Summary: Students leverage technology to take an active role in choosing, achieving, and demonstrating competency in their learning goals, informed by the learning sciences.
- 1.1.a Students articulate and set personal learning goals, develop strategies leveraging technology to achieve them and reflect on the learning process itself to improve learning outcomes.
- 1.1.b Students build networks and customize their learning environments in ways that support the learning process.
- 1.1.c Students use technology to seek feedback that informs and improves their practice and to demonstrate their learning in a variety of ways.
- 1.1.d Students understand the fundamental concepts of technology operations, demonstrate the ability to choose, use and troubleshoot current technologies and are able to transfer their knowledge to explore emerging technologies.
1.2 Digital Citizen
- Summary: Students recognize the rights, responsibilities and opportunities of living, learning and working in an interconnected digital world, and they act and model in ways that are safe, legal and ethical.
- 1.2.a Students cultivate and manage their digital identity and reputation and are aware of the permanence of their actions in the digital world.
- 1.2.b Students engage in positive, safe, legal and ethical behavior when using technology, including social interactions online or when using networked devices.
- 1.2.c Students demonstrate an understanding of and respect for the rights and obligations of using and sharing intellectual property.
- 1.2.d Students manage their personal data to maintain digital privacy and security and are aware of data-collection technology used to track their navigation online.
1.3 Knowledge Constructor
- Summary: Students critically curate a variety of resources using digital tools to construct knowledge, produce creative artifacts and make meaningful learning experiences for themselves and others.
- 1.3.a Students plan and employ effective research strategies to locate information and other resources for their intellectual or creative pursuits.
- 1.3.b Students evaluate the accuracy, perspective, credibility and relevance of information, media, data or other resources.
- 1.3.c Students curate information from digital resources using a variety of tools and methods to create collections of artifacts that demonstrate meaningful connections or conclusions.
- 1.3.d Students build knowledge by actively exploring real-world issues and problems, developing ideas and theories and pursuing answers and solutions.
1.4 Innovative Designer
- Summary: Students use a variety of technologies within a design process to identify and solve problems by creating new, useful or imaginative solutions.
- 1.4.a Students know and use a deliberate design process for generating ideas, testing theories, creating innovative artifacts or solving authentic problems.
- 1.4.b Students select and use digital tools to plan and manage a design process that considers design constraints and calculated risks.
- 1.4.c Students develop, test and refine prototypes as part of a cyclical design process.
- 1.4.d Students exhibit a tolerance for ambiguity, perseverance and the capacity to work with open-ended problems.
1.5 Computational Thinker
- Summary: Students develop and employ strategies for understanding and solving problems in ways that leverage the power of technological methods to develop and test solutions.
- 1.5.a Students formulate problem definitions suited for technology-assisted methods such as data analysis, abstract models and algorithmic thinking in exploring and finding solutions.
- 1.5.b Students collect data or identify relevant data sets, use digital tools to analyze them, and represent data in various ways to facilitate problem-solving and decision-making.
- 1.5.c Students break problems into component parts, extract key information, and develop descriptive models to understand complex systems or facilitate problem-solving.
- 1.5.d Students understand how automation works and use algorithmic thinking to develop a sequence of steps to create and test automated solutions.
NGSS MS.Engineering Design
The Next Generation Science Standards (NGSS) are K–12 science content standards.- MS-ETS1-1. Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.
- MS-ETS1-2. Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.
- MS-ETS1-3. Analyze data from tests to determine similarities and differences among several design solutions to identify the best characteristics of each that can be combined into a new solution to better meet the criteria for success.
- MS-ETS1-4. Develop a model to generate data for iterative testing and modification of a proposed object, tool, or process such that an optimal design can be achieved.
NGSS HS.Engineering Design
The Next Generation Science Standards (NGSS) are K–12 science content standards.- HS-ETS1-1. Analyze a major global challenge to specify qualitative and quantitative criteria and constraints for solutions that account for societal needs and wants.
- HS-ETS1-2. Design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems that can be solved through engineering.
- HS-ETS1-3. Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs that account for a range of constraints, including cost, safety, reliability, and aesthetics as well as possible social, cultural, and environmental impacts.
- HS-ETS1-4. Use a computer simulation to model the impact of proposed solutions to a complex real-world problem with numerous criteria and constraints on interactions within and between systems relevant to the problem.
NGSS 3-5.Engineering Design
The Next Generation Science Standards (NGSS) are K–12 science content standards.- 3-5-ETS1-1. Define a simple design problem reflecting a need or a want that includes specified criteria for success and constraints on materials, time, or cost.
- 3-5-ETS1-2. Generate and compare multiple possible solutions to a problem based on how well each is likely to meet the criteria and constraints of the problem.
- 3-5-ETS1-3. Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved.