Energy Harvesting from Motions of a Robotic Worm

We present a piezoelectric energy harvester that is assembled on a soft robot and converts its mechanical locomotion to electricity. The piezoelectric transducers are used in various applications because of their durability, flexibility, and self-powering characteristics. In this study, we demonstrate a piezoelectric transducer that converts the soft robot's motion to electricity to provide power for the soft robot sensors such as strain sensors. The system consists of a piezoelectric strip that is placed on the soft robot. External stimuli provided by pneumatic pressurization actuates the soft robot and moves it forward. The inflation and deflation of the soft robot cause mechanical deformation which results in a voltage generated at the piezoelectric layer. We consider the piezoelectric harvester elongator type mechanism that works by mechanical extension and compression. An AC-DC conversion circuit is used to obtain 1.5-2 V DC output voltage from the piezoelectric harvester to charge a capacitor for use of sensors. AC-DC conversion circuit consists of a resistance in series with the piezoelectric, a full-bridge rectification circuit, and an LM317T voltage regulator. The energy harvesting mechanism offers an alternative power source that reduces the external electrical power requirements of the robot and extends the lifetime of onboard batteries.