Stable Haptic Interaction: Time Domain Passivity Approach
Stable interaction with high stiffness virtual environments (VEs) still remains a challenging issue for kinesthetic haptic devices with impedance causality. In particular, it has been recognized that the maximum achievable impedance with the traditional digital control loop is limited by the lack of information to the controller caused by time discretization, position quantization, related to the use of encoder as a position sensor, and zeroth-order hold (ZOH) of force command during each servo cycle. These lead to energy leak and eventually instability if not dissipated through the intrinsic friction of the device, controller, or damping from the user’s grasp.
Our lab has performed several studies to guarantee stable haptic interaction with high stiffness VEs. As an initial effort, we have proposed an energy-based approach, the so-called time-domain passivity approach (TDPA), which injects an adaptive virtual damping to satisfy the time-domain passivity constraint.
Stable Haptic Interaction: Memory-based Passivity Approach
Stable Haptic Interaction: Less Conservative Approach Is Coming
Passivity has been a major criterion on designing a stable haptic interface due to many advantages. However, passivity has been suffering from its intrinsic conservatism since it only represents a small set of the whole stable region. Therefore, there was always limitation to increase the performance due to the small design margin from the passivity criterion.
We at IRiS lab are currently working on less conservative approach for stable haptic interaction.
Master Device for Intuitive Teleoperation
In teleoperation, a master device should not only allow human operator to easily give command to a slave robot with an intuitive manner, but also improve the operators’ perception of the target slave and its environment by enabling richer interaction feel.
Our lab is interested in developing non-conventional master devices for different teleoperation areas. one of the early works from our lab is developing a novel tele-driving interface for wheeled and tracked vehicles. Currently, we are developing a novel master device for underwater vehicles and manipulators.
Mobile robot teleoperation
Our lab proposed several methodologies to improve the performance in mobile robot teleoperation such as position-velocity switching command strategy and velocity dependent adaptive feedback gain scheduling method.
Improving Teleoperation Performance: Surgical Robot Teleoperation
As MIS (Minimal Invasive Surgery) growing rapidly, new and more complicated surgical instruments are developed to make the tool reliable and decrease the incision area as small as possible. However, this increase the surgeon’s mental burden for properly tele-operating the complex surgical robot systems.
Our lab is developing a teleoperation method to reduce the surgeon’s mental workload considering ergonomics.
*Courtesy of da Vinci Surgery.