Make a Paper Walking Robot Dog
30-60 min
Ages 8+
What Will You Make?
Create a gravity-powered quadruped from an index card. For this project, you’ll build a robot that moves without any computers or sensors to guide it. In fact, this version is so basic, it doesn’t even need a motor!
What Will You Learn?
You will learn folding, measuring (or eyeballing measurements), cutting along lines.
Making Your Dog
Introduction
To start, look at the example to get an idea of how your robot dog will look, and then draw your own fold and cut lines. First, measure the length of the card or heavy paper you are using. Divide the length into three, and mark each section on the card. In other words, if your card is 4 inches by 6 inches, make marks along the longer side at 2 inches and 4 inches.
Step 1
To make the front and back leg sections, fold up the ends of the card (Figure A ). Check that the sections are equal by flipping the card over and standing it up on its legs like a table. Unfold.
Step 2
To make the head and tail: mark a narrow strip down the middle of the front and back sections you just made, going from the fold to the edge of the paper (Figure B). (If there are lines on the index card, use them to guide you.)
Step 3
To make the front legs, draw a line on either side of the front end. Repeat on the other end of the card to make the back legs (Figure C ).
Step 4
To make a wide stomach (which helps the dog rock side to side as it walks), cut off the bit that is left between the legs and the edge of the card (Figure D ).
Step 5
Fold the legs up (Figure E ) and then flip the card over.
Step 6
Bend the head and tail up (Figure F ). To help the dog rock side to side and lift its feet to walk, round off the feet like a rocking chair. Draw a curve on each foot, starting at the inside corner and going up a little ways along the side of the card (Figure G ). Cut along the lines. Test that the legs are still even and trim them if they are not.
Step 7
Finish the head by folding down a little at the tip. Finish the tail by curling it around a pen (Figure H ).
Step 8
To get the dog to walk, place it at the top of the ramp. Tilt the ramp until the dog starts to move. You can get it going by tapping on one side of its belly (Figure I).
Troubleshooting Tips
If it doesn’t work, what could be the problem? Look at:
Balance: Are the front and back legs the same length?
Legs: Is the fold connecting them to the body sharp enough to allow them to move?
Feet: Are they curved evenly? • Rocking: Does the dog tilt from side to side as it moves? If not, try adding a little weight by taping a paperclip underneath each side.
Body: Is it stiff enough? If not, make it thicker with tape, or add another layer of paper.
Ramp: Is it tilted too little or too much? Is it too slippery?
What Is Happening Here?
Powered by Gravity
This mechanism is powered by the pull of gravity. This style of motion is known as passive dynamic walking.
Scientists used to think that people and animals relied on their brains to control the way they walked and keep their balance. But it turns out that a lot of that control is taken care of by the legs themselves — an example of a smart body in action! The legs swing back and forth and shift the weight of the body from side to side. Once they get started, the legs keep going forward until the brain tells them to stop. It’s an efficient and stable system, which is why robotics engineers have borrowed it to use in walking robots. Most passive dynamic walkers are bipeds and walk on two legs. When they move, they shift all their weight to one leg, and let the other leg swing forward. Then they shift their weight the other way to allow the other foot to take a step. (Check out the book BOTS! to see how to make a two-legged version.)
However, some robotics labs have tried making passive dynamic walkers with three, four, or even more legs! The extra legs help with balance, but they also make the pattern of walking much more complicated. When a dog walks along, it only picks up one foot at a time. A cheetah or a race horse can trot with two feet always on the ground at the same time, or gallop with just one foot touching down as it speeds by. Trying to get a four-legged robot to move in a realistic way is a big problem scientists are still trying to solve.
One robot dog called Spot, made by Boston Dynamics, has a gait (or pattern of walking) that’s so real, it’s spooky. Spot’s legs bend the same way real dog legs bend. And with its sensors and programming, Spot is good at getting itself back up if it tumbles over on its side. The Walking Robot Dog you will be making, on the other hand, doesn’t even have knees, so its legs don’t bend. But it does move one front foot and then the other in a slow, steady rhythm as it makes its way downhill. It also has a long skinny neck and a small head, like Spot. The head and tail help keep it balanced. Even though it isn’t as advanced as Spot, it’s still pretty good at not falling over.
What Is Next?
Go Beyond
Can you design a two-legged walker that doesn’t need back legs? How will it balance? How will its legs swing back and forth? (Think about different kinds of two-legged walkers from real life, such as birds, or their cousins the dinosaurs.)
Take a look at some early passive dynamic walkers from Cornell University: ruina.tam.cornell.edu/research/topics/robots.
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:
- For the Robot:
- Index card, cardstock, or construction paper (get two sheets if you’re using it for the ramp as well); 4 inches by 6 inches is a good size
- Pen, pencil, or marker
- Scissors
- Ruler
- Tape
- Optional: 2 paper clips
- For the Ramp:
- A board or other large flat object, about a foot long
- Something to prop up the ramp, such as a pile of books
- Optional: a covering such as construction paper, rough cardboard, or a rubbery mouse pad to give the ramp a little traction
