Vascular intervention involves inserting a catheter and guidewire into blood vessels to diagnose and treat a disease in an X-ray environment. In this conventional vascular intervention procedure, the doctor is exposed to considerable radiation. To reduce the exposure, we developed a master–slave robot system. A steerable catheter is employed to shorten the task-time and reduce the contact force applied to the vessel walls during catheter insertion. The steerable catheter helps to select a vascular branch; thus, the radiation exposure time for patients is reduced, and perforation in the patient’s vessel is prevented. Additionally, the robot system employs a haptic function to replicate the physician’s tactile sensing in vascular intervention. In this study, the effectiveness of the steering catheter and haptic function was demonstrated experimentally in comparison with a conventional catheter.

Stackable mechanism architecture has demonstrated effective gravity-balancing over entire workspaces. Adjustable balancing is required when balancing is broken due to changing the payload at the distal end of a mechanism. In this paper, adjustable balancing of the stackable mechanism for a variable payload is investigated. For this, balancing conditions for three adjustable balancing methods are suggested, and a new balancing method combining a spring and counterweight is considered as an effective means of adjustable balancing for variable payloads. The excellent performance of the system is proven through experiments. Electromyography (EMG) sensors are employed to measure the amount of energy expenditure during the drilling task. It was verified through several tests that an operator holding a drill mounted at the distal end of a stackable arm felt less energy compared to an operator holding the drill directly in free space. The developed balancing arm was successfully applied during a mastoidectomy. A 3-step warning algorithm along with a braking function was found to be effective for safe surgery.

Woo J, et al. Yonsei Med J. 2017 Jan;58(1):139-143. https://doi.org/10.3349/ymj.2017.58.1.139

Conventional vascular intervention (VI) procedures are typically performed manually under exposure to X-rays, whereby several problems are presented that need to be addressed owing to the patients and doctors being exposed to large amounts of radiation. In such cases, employing radiation protection units is not a long-term solution to avoid physical damage. Therefore, to overcome these issues, we propose a robotic VI system in this study. Moreover, we compare the extent of radiation exposure in the case of the conventional manual VI procedure with that in the case of the robotic procedure. The radiation exposure is then analyzed from the perspective of the doctor. Subsequently, the results of usability tests for two proposed master devices are presented in terms of the NASA task load index (NASA-TLX) and the system usability scale (SUS) score. To verify the effectiveness of the robotic VI system, animal experiments are conducted using a pig model. Among the two types of master devices tested with the proposed robotic VI system, the ergonomically designed 2-degree-of-freedom master device is found to be more effective than the joystick-type device in terms of the usability test scores. Hence, the proposed robotic VI procedure is shown to be advantageous in terms of reducing radiation exposure and improving usability.

Light machining tasks by robots are becoming an important issue to replace shortages of human resources. To improve the quality, safety and overall performance of manufacturing process, the modeling for estimation of forces and torques during the machining operations is on demand. In parallel, the digital model has also been developed which allow to detect the foul conditions, save energy & time and optimization of the real manufacturing process. Digital twins are one of them which use the offline and online data to simulate the physical manufacturing process. However, the empowerment of digital twins can be improved further by developing more accurate mathematical model which allow to simulate the physical machining process in real time. Accordingly, this paper presents a formulation for the mechanics of robotic light machining tasks to empower the digital twin. In this paper, a generalized impulse model is employed to analyze a light machining task that combines the linear and angular motions. For the implementation of an impulse model-based approach, the concept of both effective mass and effective inertia is newly introduced to reflect the dynamics of the environment, which depends on the hardness of the material and process parameters (feed rate and speed (rpm) etc.) of the machining task. Furthermore, optimal feed rates are calculated with consideration of effective mass/effective inertia and minimum task completion time. Moreover, simulations are carried out to choose the feasible direction of linear and angular velocities and optimal non-singular workspace for light machining tasks. Finally, the proposed methodology is validated through a quantitative comparison of simulation and experimental results by performing the drilling and milling tasks. A 6-DOF Universal robot (UR 5e) is used for simulations and experiments to corroborate the effectiveness of the proposed algorithms for light machining tasks. The developed methodology will certainly empower the digital twin for their physical analog during light machining operations.

This paper deals with workspace analysis for a 3-RRR spatial parallel manipulator through changes of robot parameters as well as rotation angles of a ball-joint. Also, based on the tendency, the kinematic parameters and the rotation angle of the ball joint are determined to get a desired workspace.