A novel surgical palpation probe installing a miniature 6-axis force/torque (F/T) sensor is presented for robot-assisted minimally invasive surgery. The 6-axis F/T sensor is developed by using the capacitive transduction principle and a novel capacitance sensing method. The sensor consists of only three parts, namely a sensing printed circuit board, a deformable part, and a base part. The simple configuration leads to simpler manufacturing and assembly processes in conjunction with high durability and low weight. In this study, a surgical instrument installed with a surgical palpation probe is implemented. The 6-axis F/T sensing capability of the probe has been experimentally validated by comparing it with a reference 6-axis F/T sensor. Finally, a vivo tissue palpation task is performed in a simulated surgical environment with an animal organ and a relatively hard simulated cancer buried under the surface of the organ.

This paper presents a novel six-axis force/torque (F/T) sensor for robotic applications that is self-contained, rugged, and inexpensive. Six capacitive sensor cells are adopted to detect three normal and three shear forces. Six sensor cell readings are converted to F/T information via calibrations and transformation. To simplify the manufacturing processes, a sensor design with parallel and orthogonal arrangements of sensing cells is proposed, which achieves the large improvement of the sensitivity. Also, the signal processing is realized with a single printed circuit board and a ground plate, and thus, we make it possible to build a lightweight six-axis F/T sensor with simple manufacturing processes at extremely low cost. The sensor is manufactured and its performances are validated by comparing them with a commercial six-axis F/T sensor.

This paper presents a variable admittance control method to achieve intuitive human–robot interactions that consider human intentions. Human intention is classified into two categories—direct and indirect. With respect to direct intention, the concept of standard force is introduced to adjust the interacting force. The proposed variable admittance control method improves intuitiveness when velocity is used as an estimate of direct intention. In the estimation of indirect intention, a force guidance method is suggested to make a robot follow and guide a human. The proposed control methodology is adapted to a six-DOF manipulator based on a one-dimensional analysis. The experiments are conducted with a manipulator (Universal Robots, UR10) and a force/torque sensor (Robotus, RFT60-HA) to evaluate the performance. The experiments validate that variable admittance control enhances the execution time, accuracy, and comfort of the operator.

A novel force-sensing mechanism for surgical robotic systems is required for further innovation of robotic-assisted minimally invasive surgery (RMIS). In this paper, novel sensorized surgical forceps are presented with five-degree-of-freedom (5-DOF) force/torque (F/T) sensing capability: a grasping force, a 3-DOF manipulating force, and a rotational torque acting at the forceps. Two compact 3-DOF force sensors are integrated into the proximal region on two jaws of the forceps to measure 5-DOF F/T. The forceps also present important advantages for actual use in RMIS, such as miniaturization, compatible configuration to various shapes of surgical forceps, and packaged sensor electronics. In this study, the forceps are designed and manufactured at a low cost and are even disposable. To evaluate the forceps in a surgical robotic environment, the instrument is installed in a surgical robot, named S-Surge. In the environment, the 5-DOF F/T sensing capability is evaluated through comparison with reference sensors.

This paper presents a mechanism for an in-pipe robot, called the Multifunctional Robotic crawler for In-pipe inspection VII (MRINSPECT VII), which is under development for the inspection of gas pipelines. Applicable pipeline diameters are from 150 to 200 mm. The robot is based on a multiaxial differential gear mechanism and designed to adapt to the varying inside geometries of pipelines, such as elbows, by mechanically modulating the velocities of active wheels without any control effort. In addition to the differential gear mechanism, the MRINSPECT VII is equipped with an active adhesion mechanism for improving traction ability and a rescue mechanism for easy retrieval of the robot in the case of trouble inside pipelines. In this paper, the multiaxial differential gear mechanism is mainly explained, and the construction of the robot mechanism is detailed. Finally, the effectiveness of the mechanism is experimentally demonstrated with the MRINSPECT VII.