Research in the Mechatronics and Haptic Interfaces (MAHI) Lab involves studies of how haptic interface machine design affects haptic fidelity and perceived simulation quality, developing control systems for virtual and remote environment systems that assure stability and transparency, and the application of haptic devices for training and rehabilitation. Recently the lab has focused on the design of perceptual overlays in virtual environments that are active rather than passive. Passive virtual fixtures have been the primary perceptual overlay in haptics, and have been used extensively as "virtual rulers" in teleoperation environments to improve operator performance of pick-and-place tasks. Active assistance in the form of shared control between the haptic device and the human operator has the potential to elicit even better performance in virtual and remote environment interactions, especially for dynamic tasks, and also has implications for improving training and rehabilitation effectiveness. The lab is also exploring new modes of human-robot interaction, and robot-mediated human-human interaction for skill transfer and rehabilitation.