Figure 2. Piezostack vibration - Robot locomotion principle

From

Friction Difference as Principle of Robot Locomotion

Alexander Gmiterko, Ľubica Miková, Ivan Virgala, Tomáš Lipták, Michal Kelemen

Journal of Automation and Control. 2017, 5(2), 50-53 doi:10.12691/automation-5-2-4