Robotic ultrasound (US) systems represent an emerging frontier in medical imaging. A fundamental component of these systems is the rigid body transformation between the robot flange and the attached US probe, which enables mapping of visual data from image space to the robot's reference frame. Traditionally, calibrating this transformation has been a tedious process, complicated by equipment demands and operational constraints arising from the probe's narrow field of view. This work presents a novel calibration strategy based on conic sections geometry, which offers several key simplifications over existing approaches: 1). It requires no external equipment beyond a single cone phantom; 2). It operates with a small input size and imposes no strict alignment or motion constraints on the US scan plane during calibration; and 3). It employs a straightforward pattern analysis pipeline to process images acquired from phantom scans. Experimental validation results show that the proposed method achieves accuracy comparable to existing state-of-the-art approaches while delivering superior precision, thereby demonstrating enhanced calibration reproducibility enabled by its streamlined workflow. These advantages make this method particularly suitable for application in clinical scenarios that require frequent and efficient calibration.

The remote center of motion (RCM) constraint is a vital requirement in the design of robotic systems for transrectal ultrasound (TRUS) probe-scanning. This paper presents the design and development of a novel RCM-constrained manipulator specifically tailored for TRUS probe-scanning applications. The proposed system features a six-degree-of-freedom (6-DoF) parallel-serial hybrid mechanism that enables the TRUS probe to perform pivot and spin rotations while maintaining the RCM constraint. Subsequently, the kinematic model incorporating the RCM constraint is derived. Additionally, a geometry-aware path planning method is then introduced, considering variations in the desired rotation targets. This method parameterizes distance metrics on SO(3) (a Lie group) using coordinate-free Riemannian geometry, enabling the dynamic optimization of rotation orders to minimize the calculated Riemannian metrics. Furthermore, a smooth rotational trajectory generation method is proposed, constructing rotation curves between the ordered matrices on SO(3) while minimizing angular acceleration. Both simulations and experimental results validate the effectiveness and practicality of the proposed manipulator and its path planning method.

In robotic teleoperation systems, the effectiveness of teleoperation relies heavily on the operator performing control actions, underscoring the importance of master device design. Breaking away from the mechanical framework that relies on complex structures and restricts workspace, this paper adopts a new magnetic method and introduces a wireless magnetic master device (MMD) with an expandable, singularity-free workspace, designed to enhance maneuverability and operational reach. Specifically, the concept and development of the MMD for robotic teleoperation are presented, followed by an exploration of key technical aspects, including a six-degree-of-freedom (DoF) tracking approach using dual magnetic localization and controller design for the robotic arm using the MMD. Finally, the proposed method’s feasibility and accuracy are validated through magnetic localization and teleoperation control tests. Results indicate that the MMD achieves six-DoF localization with an average Euclidean localization error ofet= 0.0018 m and an average Geodesic distance error ofeR= 0.0604 rad within the central region of the workspace, and six-DoF manipulation (velocityet= 0.0062 m andeR=0.2091 rad in tests. Furthermore, the overall teleoperation control framework achieves tracking accuracy withet= 0.0085 m andeR= 0.1475 rad in robotic calligraphy task; achieves a broad scanning range of 0.2746 m along they-axis in robotic ultrasound scanning task; achieves a large-angle rotation of 9.15 rad in robotic clamp rotating task. Overall, this research advances master device design, aiming to inspire further innovation in master-follower teleoperation control for human-machine systems.

Capturing stationary aerial objects on unmanned surface vehicles (USVs) is challenging due to quasiperiodic and fast floating-base motions caused by wave-induced disturbances. It is hard to maintain high motion prediction accuracy due to the stochastic nature of these disturbances, and perform object capture through real-time tracking due to the limited active torque. We introduce confidence analysis in predictive capture. To address the inaccuracy predictions, we calculate a real-time confidence tube to evaluate the prediction quality. To overcome tracking difficulties, we plan a trajectory to capture the object at a future moment while maximizing the confidence of the capture position on the predicted trajectory. All calculations are completed within 0.2 s to ensure a timely response. We validate our approach through experiments, where we simulate disturbances by executing real USV motions using a servo platform. The results demonstrate that our method achieves an 80% success rate.

In this paper, a new capture system for UAV precision landing in a disturbed environment is proposed. Compared with the traditional visual guided landing methods, perching mechanism based methods, and tethered landing methods, the proposed system takes into account the stability during landing process and retains the high accessibility of the UAV. The proposed system consists of a winch subsystem and a magnetic catcher device. They establish an automatic tethered-UAV system for landing before the UAV touchdown. We analyzed the design principle as well as the feasibility of the magnetic catcher. An optimization problem is formulated to obtain a better layout of magnets on the catcher. The problem is relaxed based on interpolation simulation of attraction force. Experiments are conducted both in indoor and outdoor environments based on different UAV platforms respectively. The results validate that the catcher design and the capture system can achieve a successful landing in both cases.