Caterpillar Robot with SMA muscle wires


The caterpillar robot is driven by two artificial muscles made of SMA (shape memory alloy). Make it together with your friends and try a caterpillar race!


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Preparation: 1 hour (for SMA)
Process time: 30 min


  • SMA (Instructions are here)
  • Rubber sheet
  • Straw
  • Batteries (1.3V 2pieces)
  • Battery case
  • Cables / wires
  • Button switches

Tools and Equipments

  • Scissors
  • Stapler
  • Ruler
  • Breadboard



Cut the rubber sheet in the size of 7cm x 2cm. Also cut 2cm of the straw and cut it vertically in half.


Cover the edge of the rubber sheet with the straw and staple it. This makes the edges slippery, which makes the caterpillar’s locomotion smoother. Cover the other edge of the rubber sheet with the straw and staple it in the same direction.

Make slits

Cut slits in 1/2~2/3 the width of the rubber sheet. Do this for both sides, making sure the slits don’t overlap. The rubber sheet’s stiffness can be tuned by changing the cutting depth and the slit’s pitch.

Attach the SMAs

Pass the SMA through the slits of the rubber sheet. The distance between the two slits should be 2 times longer than the length of the SMA. Repeat this for the opposite side.

Refer to the illustration below.

Connect the power

Briefly connect the power source to the SMA (0.5~1sec) by pressing each of the wires from one SMA to the positive red wire and the negative black wire of the battery case. The SMA will shrink when electric current is applied. Be careful not to connect it for too long or the SMA will burn out.


Connect the SMA, button switches and power on the breadboard. You can control the caterpillar robot with two button switches.

Image of the circuit diagram

Circuit Diagram, Powered by Fritzing

Caterpillar race

Make the robots together with your friends, and enjoy the race!


Other recipes

  • Instructions for making SMA : SMA

More Informations


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