One of the recent developments in physical reservoir computing, which uses the complex dynamics of a physical system as a computational resource, is the use of a pneumatic pipeline system as a computational resource. This uses the dynamics of air for computation, and because it is lightweight and power-saving, it is used for gait-assist control using a soft exoskeleton with pneumatic rubber artificial muscles. In this study, we verified that by feeding back the estimated information to a pneumatic pipeline system, the pneumatic physical reservoir computing can generate periodic pressure changes as a stable limit cycle, such as those seen in walking. A pneumatic reservoir with feedback loops was modeled to generate limit cycles in the simulation, and it was confirmed that the system could generate limit cycles with high accuracy even from initial positions far from the target limit cycle. This system is expected to be applied to assist walking movements with a soft exoskeleton with a lightweight computational device.

In this study, we developed a selective driving joint forceps (SDJF) for laparoscopic surgery. The SDJF has a mechanism that the driving joints can be selected arbitrarily, therefore each joint doesn't require an individual actuator for operating. The developed SDJF has six joints that can be operated using only four actuators. Each joint has 2-degrees-of-freedom (DOF) of flexion. Therefore, the SDJF has the same working area as the forceps having six driving joints (each joints can bend ±30° around the X and Y axes). The mechanism of the SDJF is realized by fixing each joint with a collar made of shape memory polymer. The proposed mechanism not only reduces the number of actuators required for joint operation, but also has the rigidity of the forceps, which is important in surgery. In addition, a driving section of the forceps is driven by pneumatic cylinders, therefore, the forceps joint has high-back-drivability, lightweight and high-output. We measured the heating and cooling time required to change the driving joint, dynamic response and rigidity of the prototype SDJF.

In this study, a robotic forceps with a wrist joint using visual SLAM for joint angle sensing was developed. The forceps has a flexible joint connected to the wrist joint at its rear end and the motion of the rear joint is driven by a parallel linkage. A monocular camera attached on the rear of the parallel linkage is in charge of position sensing, and the joint angles are estimated from the pose of the camera. The pose of the camera is obtained by a visual SLAM. The visual servo system realizes a simple attaching mechanism. The static and dynamic positioning experiments are conducted. We confirmed that the visual servoing system controls the forceps tip within the error of 3 deg in the motion range of 50 deg.

A method to improve quality of life of elderly people is to increase muscle strength. The purpose of this study is to develop a machine to improve muscle strength effectively. In this paper, we proposed a muscle strength training machine that exerts variable resistance using pneumatic artificial rubber muscle. In addition, we observed the effect on muscle activity by using the proposed machine with predictable and unpredictable load change patterns. Experimental results showed that there was a difference between the rising time of muscle activity and the maximum amplitude of electromyogram depending on predictability of the load change and showed the possibility of effective muscle strength improvement against unpredictable load using the arm curl machine.

Motor skill learning is fundamental in many physical activities of human. In the processes of learning of motor skills, learners often receive visual or physical information about postures from teachers. However, the information about postures usually cannot be transmitted precisely. In this paper, we propose a motion teaching system to transmit teachers' motion to learners directly by using a motion capture and an assist suit. The assist suit, which has a pneumatic artificial rubber muscle (PARM) as an actuator, was designed to move a learner's hip joint with less loss of assistive force and less constraint of motion. Hip joint motion of a teacher can be transmitted to the assist suit by master-slave control. In addition, to compensate the delay of the PARM, posture of the teacher is predicted before the occurence by a recurrent neural network by using electromyogram signals and the past joint angle. We confirmed the system can transmit a teacher's motion to a learner in real time, and with the neural network, the delay of the learner's motion could be suppressed to approximately 0.1s, which is enough to feel visual and physical information synchronous. Therefore, the proposed motion teaching system would have the ability to transmit teachers' motion to learners visually and physically with precision sufficient to facilitate skill transmission.

Surgical robot systems increase the operability and efficiency of laparoscopic surgery. Forceps manipulators with the diameter less than 3mm can drastically reduces the invasion to the patient, compared to those used in current robot systems with the diameter of 5mm or more. In this paper, we propose a novel surgical manipulation system with Φ3mm forceps. Instead of introducing costly grasping mechanisms, the proposed system consists of a pair of rods driven by two robotic forceps holders, so that they can synchronously grasp, move, and rotate objects, in manner of a chopstick. Five-DOF kinematic model is constructed, which includes three-DOF translational motion, a sliding motion, and a grasping motion. A master-slave system is constructed and the tracking performance of the controller is validated. We also experimentally confirmed that the proposed system can perform the block-transfer task, which is common in training of surgeons, and the block-rotation task.

Surgical robot systems for minimally invasive surgery (MIS), such as laparoscopic surgery, typically employ remote center of motion (RCM) mechanisms consisting of rigid links. Although the rigid body mechanisms have high reliability based on their stiffness, their large volume interferes the workspace of surgeons and the rigidity of pivot point requires precise positioning during the setup of robots. In this paper, a space-saving and light-weight manipulator to hold a forceps is developed, which has a compliant RCM mechanism by using a flexible joint. The manipulator consists of elastic metal springs and a wire to inflect the joint. Since the proposed flexible link has 2-DOF motion of protrusion and bending, the location of the pivot point can be variable, allowing easier adjustment of pivot point before or during the operation. We proposed the method to vary the radius of curvature of the flexible joint and pitch angle of forceps by controlling the position of the joint and the tension of the wire with two pneumatic cylinders. For more accurate manipulation, we modeled the holder in terms of material mechanics and experimentally identified static characteristics of the flexible joints. Experimental results show that the proposed model and control law achieve the rotational motion of the forceps with a remote and variable pivot point.

Development of intuitive user interface of a dexterous forceps with wrist joint for minimally-invasive surgery (MIS) is important for reducing the surgeon's confusion and fatigue. In this paper, a wearable robotic forceps manipulator is proposed. By measuring the wrist attitude of the surgeon by a motion sensor and driving the forceps tip by actuators, intuitive operation is realized, compared with fully mechanical forceps. A compact and lightweight system is achieved since we adopt pneumatic actuators to drive the manipulator. In order to help the force sensing of the surgeon, the external force is measured from the air pressure and displayed in a visual way. Experimental comparison with a conventional handheld forceps and a teleoperation system is conducted and its results show the effectiveness of the proposed handheld forceps.

In this paper, a lightweight master interface for a surgical robot system is proposed. The position of the human hand is measured by a non-contact motion tracker, but the force feedback is realized by a handheld haptic device. A gripping force is displayed by a pneumatic bellows, which is smaller and more lightweight than electric motors. As for the slave manipulator, the gripper of a surgical forceps is actuated using a pneumatic cylinder. Force estimation is possible due to the back-drivability of the pneumatic actuator. Experimental results show the control performance of the haptic device and a constructed master-slave system.

In this paper, control methods to avoid the conflict of operators' commands in multi-user teleoperation system is considered. The proposed methods insert virtual nonlinear springs between the master arms and the end of wave transmission line of the multilateral controller. The nonlinear springs becomes softer when the input force from the operators are above a certain threshold and limit the input force. Experiments are conducted in order to compare the effectiveness of the methods. The experimental results show that the proposed two-step gain improves the operation performance.

This paper discusses variable-scale bilateral control for micro teleoperation. A method is proposed to synthesize robust variable-scale controllers that guarantee system stability and realize robust performance in contact with any arbitrary, but passive, operator and environment. The proposed method is based on the formulation as a robust output feedback constant scaled H∞problem. A variable scaled teleoperation system appears as a polytopic linear parameter-varying (LPV) plant, with an affine relation on the scale factors. Gain-scheduling is used to derive robust stable time-variant H∞controllers for online variable scaling. Improved controller performance is obtained through the introduction of an affine and scheduled-parameter-dependent weighting. The controller synthesis problem is formulated as a set of linear matrix inequalities (LMI’s) augmented with a nonconvex rank condition. An efficient algorithm is constructed to synthesize a set of sub-optimal controllers over the parameter space. The validity of the proposed methods are confirmed experimentally.