Daniela Maffiodo

Purpose: Balance control can be evaluated by studying the displacement of the center of pressure (CoP) during dynamic posturographic trials. However, differences in anthropometric characteristics may affect the measurement and increase intersubject variability, possibly leading to misinterpretation. This study evaluates how sex, age, and anthropometric characteristics (weight, height, and foot length) influence the CoP displacement to postural perturbations. Methods: Seventy-two healthy subjects, 31 women and 41 men, were subjected to five small impulsive perturbations applied to their back. Balance performance was quantified by three CoP parameters: the ratio between the maximum CoP displacement and the impulse of the perturbation (Δ CoP _n ), the latency ( Lat ), and the duration ( Dur ) of the CoP response. Results: A linear regression analysis evidenced that body weight and height exhibited a negative and positive relation with Δ CoP _n , respectively, which explained 48% of the Δ CoP _n variability. These relations were confirmed by simulations with a single-link biomechanical model. On the other hand, the latency and the duration of the CoP response were affected neither by the anthropometric characteristics nor by sex. Conclusion: Findings from the present study have an impact on test protocols, especially when comparing data collected from heterogeneous populations, in which case normalization with respect to the subjects’ height and weight may be necessary to use the Δ CoP _n as a postural performance index.

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.