This paper deals with robust-adaptive control of Parallel Kinematic Manipulators (PKMs), where a novel supertwisting L1 adaptive controller is proposed. The objective is to increase the robustness towards uncertainties as well as external disturbances of the standard L1 adaptive controller, by incorporating a robust super-twisting term. The proposed controller as well as the original L1 adaptive controller, are detailed for robot manipulators. Next, the experimental testbed is described, along with some implementation issues on FOEHN parallel robot. The proposed control scheme is compared with some existing literature controllers in two experimental scenarios, highlighting notable improvements in tracking performance reaching up to 75% with respect to the standard L1 adaptive controller.