These mechanisms were designed for Jessica Lee’s effort to produced a spine engaging gripper.
J. Lee, M. Plecnik, J. Yang, and R. S. Fearing, 2018. “Self-Engaging Spined Gripper with Dynamic Penetration and Release for Steep Jumps,” IEEE 2018 International Conference on Robotics and Automation (ICRA), May 21-25, 2018, Brisbane, Australia. (link)