Electric motors, with a fixed reduction ratio, have a large unused operating region when mimicking muscle movements owing to the difference between the force-velocity curves of electric motors and muscles. This unused region can be reduced by changing the reduction ratio according to the external force. However, the conventional continuously variable transmissions (CVTs) are large and heavy. Elastomeric CVT (ElaCVT), a new concept relating to CVT, is designed in this study. The primary purpose of ElaCVT is to expand the operating region of a twisted string actuator (TSA) and duplicate the force-velocity curve of the muscles by passively changing the reduction ratio according to the external load applied to the end of the TSA. A combination of ElaCVT and TSA (ElaCVT-TSA) is proposed as a linear actuator that mimics the characteristics of muscles. The deformation of elastomer changes the reduction ratio without the need for complicated mechanisms. This enables the CVT to be small and lightweight so that it can be applied to various robotic systems. The performance of the ElaCVT-TSA was evaluated by means of the experiments, and the results show that the reduction ratio was passively and continuously adjusted as the external load changed. The ElaCVT has a cylindrical shape with a length of 27 mm, a diameter of 24 mm, and weighs 12 g. The reduction ratio in the maximum velocity mode is approximately 2.31 times the reduction ratio in the maximum torque mode.

Multi-axis actuation robotics systems comprising many joints with floating-base require more stability and safety than fixed robots and thus require more considerations. In this paper, the implementation of a real-time EtherCAT control system for the TOCABI humanoid robot with 33 degrees of freedom (DOF) is described. The focus is on the development of a high-performing EtherCAT master, which enables control of the robot’s high DOF at fast communication cycles. It also explores the use of a dual-channel EtherCAT master as a redundancy mechanism to handle communication disruptions and shows that this configuration reduces the burden on the communication network and increases the communication cycle, leading to good real-time performance. To show the advantages of the system, it examines the performance of the EtherCAT communication and evaluates the impact of RTnet on real-time performance, demonstrating that a high-performing EtherCAT master with hard real-time capabilities can be established using open-source software. The results of this work demonstrate the potential of using dual channels in EtherCAT master configurations and utilizing open-source software to implement low-cost EtherCAT master systems. The paper’s contribution to the field is its indication of developing stable robot systems with high DOF, which require hard real-time capability, even with open-source software.

This paper presents the development of the JET humanoid robot, which is based on the existing THORMANG platform developed in 2015. Application in the industrial and service fields was targeted, and three design concepts were determined for the humanoid robot. First, low stiffness of the actuator modules was utilized for compliance with external environments. Second, to maximize the robot whole-body motion capability, the overall height was increased. However, the weight was reduced to satisfy power requirements. The workspace was also increased to enable various postures, by increasing the range of motion of each joint and extending the links. Compared to the original THORMANG platform, the lower limb length increased by approximately 20%, and the hip range of motion increased by 39.3%. Third, the maintenance process was simplified through modularization of the electronics and frame design for improved accessibility. Several experiments, including stair climbing and egress from a car, were performed to verify that the JET humanoid robot performance enhancements reflected the design concepts.

Avatar robots enable the teleoperation and telepresence of an operator with a rich and meaningful sense of existence in another location. Robotic avatar systems rely on intuitive interactions to afford operators comfortable and accurate robot control to perform various tasks. The ability of operators to feel immersed within a robot has drawn interest in multiple research fields to explore the future capabilities of such systems. This paper presents a robotic avatar system based on a custom humanoid robot, TOCABI, with a mobile base. Its teleoperation system was developed in response to the ANA Avatar XPRIZE. Combining the life-size humanoid robot and the mobile base allows for improved mobility and dexterous manipulation. The robotic avatar system comprises the robot/base and an operator station that incorporates haptic feedback devices, trackers, a head-mounted display, gloves, and pedals. These devices connect the robot-environment interaction and operator-avatar robot experience through visual, auditory, tactile, haptic, and kinesthetic feedback. Combining the untethered battery-operated and Wi-Fi-enabled robot with these sensory experiences enables intuitive control through the operator’s body movement. The performance of the robotic avatar system was evaluated through user studies and demonstrated in the ANA Avatar XPRIZE Finals, represented by Team SNU, where it completed 8 of the 10 missions, placing the team eighth among the 17 finalists.

Background: Recently, we developed a chest compression device that can move the chest compression position without interruption during CPR and be remotely controlled to minimize rescuer exposure to infectious diseases. The purpose of this study was to compare its performance with conventional mechanical CPR device in a mannequin and a swine model of cardiac arrest. Materials and methods: A prototype of a remote-controlled automatic chest compression device (ROSCER) that can change the chest compression position without interruption during CPR was developed, and its performance was compared with LUCAS 3 in a mannequin and a swine model of cardiac arrest. In a swine model of cardiac arrest, 16 male pigs were randomly assigned into the two groups, ROSCER CPR (n = 8) and LUCAS 3 CPR (n = 8), respectively. During 5 minutes of CPR, hemodynamic parameters including aortic pressure, right atrial pressure, coronary perfusion pressure, common carotid blood flow, and end-tidal carbon dioxide partial pressure were measured. Results: In the compression performance test using a mannequin, compression depth, compression time, decompression time, and plateau time were almost equal between ROSCER and LUCAS 3. In a swine model of cardiac arrest, coronary perfusion pressure showed no difference between the two groups (p = 0.409). Systolic aortic pressure and carotid blood flow were higher in the LUCAS 3 group than in the ROSCER group during 5 minutes of CPR (p < 0.001, p = 0.008, respectively). End-tidal CO₂ level of the ROSCER group was initially lower than that of the LUCAS 3 group, but was higher over time (p = 0.022). A Kaplan-Meier survival analysis for ROSC also showed no difference between the two groups (p = 0.46). Conclusion: The prototype of a remote-controlled automated chest compression device can move the chest compression position without interruption during CPR. In a mannequin and a swine model of cardiac arrest, the device showed no inferior performance to a conventional mechanical CPR device.