Motion-Activated Kinetic Art With Popsicle Sticks

You probably have seen the extendable arm toy like the one in the second image. It utilizes an engineering design called a “scissor structure”. I found an even more fascinating version of this structure at https://smia-experimental.com/2013/04/23/deployable-membrane-structure-design-proposal-for-the-scissors-type-system/. Basically, the traditional structure will push onward in a straight line. However, once you start to shift the intersection point of each X shape, you can get a curved moving track. When this property is applied to 3D space, you can get many interesting structural designs that can be used in architecture, furniture, etc. However, with cross point shifted along the straight arm, you can only get a curve but not enough to form a circle. One way to form a ”scissor” circle is to replace the straight stick with a bent stick, creating a star shape that expands into a circle.

In this Instructables, you will learn how to make your very own piece of kinetic art in this form, and also make it move whenever you walk near it!

Materials

For the structure:

·        Craft sticks

·        M2/M3 nuts & bolts

·        Thin metal wire

For the motion sensor:

·        Arduino Uno Chip

·        HC-SR501 PIR Infrared Sensor for Arduino with an metal strip as extended arm

·        MG996R Servo Motor

·        Wires

·        Breadboard as needed

Optional

·        Foamboard to hang the structure

·        Fishing wire or strong thin wire

·        Straws

·        Small paper box to secure the Servo

·        Paper clips

·        Various small boxes

·        Decorative paper/ideas

 Tools:

·        Hand Drill

·        Office clips

·        Wood glue

·        Arduino Power adapter/Battery pack

·        Hot glue gun

Measure the length of the craft stick. Mark two connecting points with equal distance to the ends and sides.

Each diamond needs 4 sticks, so you need 4 times the number of diamonds in the final product. For example, if we were to make an 11-diamond circle, we need 44 sticks. I 

Tip: prepare a few extra for backup, as some sticks may get damaged.

Drill the holes. The drill-head should fit your M2/M3 nuts & bolts.

As I said in the introduction, for the structure to curve enough to form a circle, the sticks need to be slightly "bent". So, we are going to glue every two sticks together with a specific angle. For an 11-diamond circle, the angle needed is about 150 degrees. In general, the bigger the angle, the more parallelograms you will need to form a circle. You have to be pretty precise: to make a 12-diamond structure, the angle is slightly below 151 degrees, and for 13-diamond structure, the angle is around 153 degrees.

Once the angle size is determined, to make sure all the angles are of the same size, draw a template and glue the sticks in pairs with drilled hole matching and sides align to the angle in template as shown. Put on a binder clip to help bonding.  

After the glue is fully cured, remove the clips. Screw every two stick structures together as shown.

Assemble pairs as shown. This way, we have alternate higher and lower connections. That is, when you look at the inner circle when done, you have alternative pairs of 1&2 (higher), 3&4 (lower). Well, if you have an odd number of diamonds, one of the connections will not follow this pattern but that is okay in our case. When the structure is contracted into the middle, it can contract most of the way!

Drill a hole on the top of the board and screw the top of one diamond in the structure onto the board. Wrap a length of fishing wire around the screw at the opposite side of this diamond. 

Contract the structure to find its center, drill a hole on the corresponding position in the board. Thread the end of the fishing wire through this hole to the back of the board (Optional: attach a circle metal/washer to the board around this hole if you have one for protection).

Thread the fishing wire through straws to the bottom at the back of the board. Tape the straw into position as shown.

Leave the tip of the fishing wire to be connected to the extended arm of the Servo motor or for manual control.

Note: Now, you can stop and enjoy the structure as is, or continue with motion sensor!

Move the fishing wire to test the movement of the structure. Mark the range of the fishing wire tip with a color pencil.

Now, knowing the length of the servo arm and the range of movement, we can calculate the angle of movement for the servo motor.

Wire the circuit as shown. Upload the attached Arduino file to your chip. The only thing you need to do is find the angle of the movement to optimally contract/expand the art piece. This is calculated in Step 6 (or you can go with trial-and-error) based on the length of servo arm, the distance of movement needed.

Secure the servo motor in a small box and hot glue it to the back of the board to the position specified earlier.

Package the circuit in a box with only PIR sensor and power cord out.  Hot glue this box to the bottom of the back of the board. If you decide to put the PIR sensor on one side of the board (rather than the middle of the board), you will need to balance it with another box to hold weights to balance out.

Hang it up on the wall. You're finished!

We first used dark grey wallpaper to cover up the board because the foam board we reused has some places teared.

For the structure itself, we used the glow-in-dark stickers. We later tried different alternatives, such as using simple expandable origami (see image).