With increasing attention to physical human-machine interaction (pHMI), new control methods involving contact force regulation in collaborative and coexistence scenarios have spread in recent years. Thanks to its internal robustness, high dynamic performance, and capabilities to avoid constraint violations, a Model Predictive Control (MPC) action can pose a viable solution to manage the uncertainties involved in those applications. This paper uses an MPC-driven control method that aims to apply a well-defined and tunable force impulse on a human subject. After describing a general control design suitable to achieve this goal, a practical implementation of such a logic, based on an MPC controller, is shown. In particular, the physical interaction considered is the one occurring between the body of a patient and an external perturbation device in a dynamic posturography trial. The device prototype is presented in both its hardware architecture and software design. The MPC-based main control parameters are thus tuned inside hardware-in-the-loop and human-in-the-loop environments to get optimal behaviors. Finally, the device performance is analyzed to assess the MPC algorithm’s accuracy, repeatability, flexibility, and robustness concerning the several uncertainties due to the specific pHMI environment considered.

Nowadays, increasing attention is being paid to techniques aimed at assessing a subject’s ability to maintain or regain control of balance, thus reducing the risk of falls. To this end, posturographic analyses are performed in different clinical settings, both in unperturbed and perturbed conditions. This article presents a new Hardware-In-the-Loop (HIL) equipment designed for the development of an automatic perturbator for postural control analysis, capable of providing controlled mechanical stimulation by means of an impulsive force exerted on a given point of the body. The experimental equipment presented here includes the perturbator and emulates its interaction with both the subject’s body and the operator performing the test. The development of the perturbator and of the entire HIL equipment is described, including component selection, modeling of the entire system, and experimentally verified simulations used to study and define the most appropriate control laws.

Objective clinical analyses are required to evaluate balance control performance. To this outcome, it is relevant to study experimental protocols and to develop devices that can provide reliable information about the ability of a subject to maintain balance. Whereas most of the applications available in the literature and on the market involve shifting and tilting of the base of support, the system presented in this paper is based on the direct application of an impulsive (short-lasting) force by means of an electromechanical device (named automatic perturbator). The control of such stimulation is rather complex since it requires high dynamics and accuracy. Moreover, the occurrence of several non-linearities, mainly related to the human–machine interaction, signals the necessity for robust control in order to achieve the essential repeatability and reliability. A linear electric motor, in combination with Model Predictive Control, was used to develop an automatic perturbator prototype. A test bench, supported by model simulations, was developed to test the architecture of the perturbation device. The performance of the control logic has been optimized by iterative tuning of the controller parameters, and the resulting behavior of the automatic perturbator is presented.

Bilateral teleoperation has witnessed significant development since the mid-20th century, a23ressing challenges related to human presence in environments with constraints or a lack of skilled professionals. This article presents the kinematic and self-collision analyses of the quasi-spherical parallel manipulator, a three-legged parallel robot used as a haptic master device. The device is designed for remote center of motion-constrained operation in the telesurgical field. Inverse and forward kinematics are thoroughly analyzed to study working modes, singular configurations, and implement a haptic control architecture. The research explores the operative and reachable workspaces of the possible working modes, comparing them to find the most suitable one. Results highlight how the addition of the self-collision phenomenon impacts the working mode choice, drastically reducing most of the modes’ operative workspaces. An anti-collision control algorithm is finally introduced to maintain the architecture within its reachable workspace.

This article explores the integration of a hapto-visual digital twin on a master device used for bilateral teleoperation. The device, known as a quasi-spherical parallel manipulator, is currently employed for the remote center of motion control in teleoperated mini-invasive surgery. After providing detailed insights into the device’s kinematics, including its geometric configuration, Jacobian, and reachable workspace, the paper illustrates the overall control system, encompassing both hardware and software components. The article describes how a digital twin, which implements a haptic assistive control and a visually enhanced representation of the device, was integrated into the system. The digital twin was then tested with the device: in the experiments, one “student” end-user must follow a predefined “teacher” trajectory. Preliminary results demonstrate how the overall system can pose a good starting point for didactic telesurgery operation. The control action, yet to be optimized and tested on different subjects, indeed seems to grant satisfying performance and accuracy.