Physical Human-Machine Interaction plays a pivotal role in facilitating collaboration across various domains. When designing appropriate model-based controllers to assist a human in the interaction, the accuracy of the human model is crucial for the resulting overall behavior of the coupled system. When looking at state-of-the-art control approaches, most methods rely on a deterministic model or no model at all of the human behavior. This poses a gap to the current neuroscientific standard regarding human movement modeling, which uses stochastic optimal control models that include signal-dependent noise processes and therefore describe the human behavior much more accurate than the deterministic counterparts. To close this gap by including these stochastic human models in the control design, we introduce a novel design methodology resulting in a Human-Variability-Respecting Optimal Control that explicitly incorporates the human noise processes and their influence on the mean and variability behavior of a physically coupled human-machine system. Our approach results in an improved overall system performance, i.e. higher accuracy and lower variability in target point reaching, while allowing to shape the joint variability, for example to preserve human natural variability patterns.

While robotic arms have been used in a vast range of application areas, so far no extensive reports on the utilization as human-machine interface exist. Compared to HMI devices from literature, the robotic arm used in this work (KUKA LBR iiwa 14 R820) features a relatively large workspace and is able to generate force and torque feedback that surpasses the capabilities of literature devices. We describe the setup allowing to use the robotic arm as HMI and analytically determine the optimal initial pose of it based on the manipulability measure of Yoshikawa. To demonstrate that the robotic arm is able to serve as HMI, we report on a comparative study with a state of the art haptic HMI featuring 20 participants. Additionally, two applications from the context of planetary exploration are presented: The first considers the teleoperation of the pan-tilt unit of a lightweight rover unit and illustrates how the large workspace of the HMI benefits the precision of the teleoperation compared to a setup with a smaller workspace. The second experiment showcases the use of the force feedback of the HMI to enable a cooperation between the operator and a supporting path-following automation in a shared control of a simulated ground robot. Both the study and the applications highlight the performance, precision and reliability of our proposed system.

With human-machine interaction continuously developing, the consideration of human experience in the design of a machine becomes increasingly relevant. An experience measure that rates how well a work or interaction state is perceived by a user is psychological flow. In this paper we introduce a novel approach to assess flow in human-machine interaction by game-theoretically modeling the interaction. To validate our approach, we perform a user study with 30 participant with a study design that allows for the manipulation of the user's experience through three experience modes. The results both validate our study design and provide indications that our approach to assess flow is promising to be developed further.