Global localization using a monocular camera is one of the most challenging problems in computer vision and intelligent robotics. In this article, a new deep neural network named Mixture Density (MD)-PoseNet is proposed to address this problem. Unlike existing learning-based global localization methods that return a single guess for the camera pose, MD-PoseNet returns multiple guesses represented in the form of a Gaussian mixture (GM). The key idea of MD-PoseNet is that the network returns the distribution of all probable camera poses instead of the most probable camera pose, and the distribution represents the multiple guesses for the camera pose. The multiple guesses returned by MD-PoseNet are, consequently, exploited in the probabilistic framework of particle filters. Finally, the proposed method is applied to four different environments, and its validity is demonstrated via experiments.

In this study, a vibrotactile pedestal with multiple actuators is developed and applied to smartphones to create a sense of information according to location and direction. As the main goal is to create a detailed sensation with a limited number of actuators, well-known sensory illusion effects are utilized to modulate vibrotactile stimuli to create an appropriate sensation. The monolithic design concept is utilized to the touch surface of the pedestal for a smooth grip so that there is no interference with screen interaction of the smartphone. Two experiments were conducted to validate whether the developed device could successfully reproduce directional and locational information according to given visual data. The results show that vibrotactile stimulation from the pedestal was useful in intuitively displaying information such as position and direction for smartphone applications. The implications of the work presented in this paper can serve as a stepping stone toward the development of smartphone applications with affluent sensory information through vibrotactile stimulation.

Anthropomorphic arm manipulators usually consist of as a series of revolute joints and links. In this paper, serial-chain manipulators are described by a novel kinematic representation using a series of type R or T joints, which are classified according to relation between a rotational axis and two adjacent links. It provides an easy intuition to describe general types among existing manipulators and also to get intuitive ideas before designing of joint and link modules of modular manipulators. From these intuitive idea about joint configurations using two types of joints, a new concept of joint module with two input and one output connections is presented. This joint module enables to couple directly between two joint modules. In addition, practical solutions of mechanical and electrical connections between joint or link modules is introduced. The connection can be established between two modules via eight types of relative positions of 45 degree intervals. Using joint and link modules, 3-DoF(Degrees-of-Freedom) modular manipulators of three kinds of joint configurations are shown representatively. After assembly, the standard D-H(Denavit-Hartenberg) parameters of three examples are obtained utilizing information of joint and link modules.

Design optimization and fabrication of concentric tube robots are time consuming because of the complexity of their workspaces and the characteristics of the superelastic materials used to make them. This paper presents a procedure for the expeditious design and fabrication of a concentric tube robot for applications that require rapid tube preparation but have less complex design constraints. This procedure reduces a 3D workspace optimization problem to a 2D problem. The continuum robot includes a heat-shrink tube to reduce fabrication time and to give it a small radius of curvature. Experimental results illustrate the feasibility of the proposed procedure.

Shape tracking using a fiber Bragg grating sensor is a promising tool due to its thin, flexible, and weightless nature. Conventional investigations attached optical fibers with a metal rod which limited the curvature due to its stiffness and increased distance between the center of the fiber and that of the sensor. We fabricated ultrathin flexible shape sensor with 110 mm length and 560 μm diameter. Its low Young's modulus and small diameter makes it suitable for application in minimally invasive surgical robot such as active cannula. The sensor causes only miniscule resistance when the cannula rotates or moves, and allows extra spaces for other surgical tools thanks to its small diameter. After the calibration, the sensor was integrated to the active cannula and overall position of the sensor was tracked. It showed an average error of 3.17 ± 1.21 % of the lengths of the measured nodes from the fixed starting point. The error was comparable to the outer diameter of the cannula, 2.8mm.

Multi-DoFs (Degrees of Freedom) manipulators with more than 6-DoF can perform complex and diverse tasks. To make these serial-chain manipulators safer, a variety of safety components were researched. If there is a crash at the end-effector of the serial-chain manipulators, components mounted on joints of the upper and lower arm can absorb the impact. Unfortunately, physical human-robot interaction does not occur only at the end-effector, a collision can happen anywhere from the base to the end-effector. If a collision occurs in the upper arm of relatively low DoFs, safety components attached to each joint may not work properly. Therefore, a study for joint configurations of serial manipulators is necessary with respect to the placement of safety components at the shoulder joint. Through various case studies, this paper verifies the appropriate joint configurations that place safety components at each revolute joint for physical human-robot safety.

A variable release torque-based compliant Spring-clutch (VCSC) and torque estimation by using distance sensor is presented. VCSC is composed of an output plate, compliance plate, compensate plate, and fixed plate. Due to these four plates, it has some functions in compliant movement, release mechanism, and gravity compensation during its work. Through these abilities, VCSC plays a role as a safe joint, reducing the impact of collisions between humans and robots. Also, it estimates the torque applied to a joint from a compressed length of a spring, using a distance sensor.

Interaction with humans is inevitable for service robots, which results in safety being one of the most important factors in designing the robots. Compliant component is an answer to the safety issue at the cost of performance degradation. In order to reduce the performance degradation, manipulators equipped with variable stiffness have been studied by many researchers. This paper presents a variable stiffness joint (VSJ) designed for a robot manipulator, as well as a control scheme to control the stiffness and position of the VSJ. Compliance is generated by leaf springs and two actuators are used to control the position and stiffness of the joint using four-bar linkages. Two actuators in parallel configuration are connected to the spring. Changing the effective length of the spring results in a change in stiffness. The position of the joint is controlled via two actuators rotating at the same speed in the same direction. A nonlinear controller is used to control the VSJ, and a singular perturbation model is adopted to prove the stability of the closed-loop system. Experiments are conducted to show that the position and stiffness are controlled independent of each other, and having less stiffness at the joint helps in making an unexpected collision with an object safer.

Safety of a manipulator designed to be used at home requires different approach than industrial robots, where safety is achieved mainly by decreasing the interaction with humans. Robots for applications at home, however, require frequent interaction with humans. Introducing compliant component gives the answer to the safety issue at the cost of performance degradation. In order to reduce the performance degradation, manipulators equipped with variable stiffness have been studied by many researchers. This paper presents a variable stiffness joint(VSJ) designed for a robot manipulator. The stiffness is generated by leaf springs and two actuators are used to control the position and stiffness of the joint. Changing the effective length of the spring results in change in stiffness. The position of the joint is controlled via rotating two actuators at the same speed in the same direction. The stiffness is controlled when the two actuators rotate in the different speed. Experiments are conducted to show that the position and stiffness are controlled independent with each other and having less stiffness at the joint helps in making unexpected collision with object safer.

Service robots are anticipated to be used in unstructured areas such as homes, hospitals, and public areas in the near future. However, safety issues need to be addressed before this can occur. In particular, robot manipulators that handle objects by physical contact run the risk of colliding with people or objects. Thus, it is important to prevent collisions that could injure people and damage robot manipulators. In this study, a safe joint mechanism is developed to ensure the safe use of a manipulator. This mechanism, termed `Spring-Clutch,' is a simple passive mechanism that consists of a coil spring and a CAM mechanism. When a torque is applied that is less than a threshold value, Spring-Clutch functions as a rigid joint between the input and the output. However, when an applied torque exceeds the threshold, angular displacement occurs between the input and output to reduce the collision force. If the applied torque is removed, Spring-Clutch immediately returns to its nominal position without the need for additional operations. This paper describes the design principles and performance of Spring-Clutch, and discusses the possibility of its practical use as a joint mechanism for safe manipulation.

A robot joint with a variable stiffness unit is presented. The variable stiffness unit (VSU) is composed of a motor, two rings that consist of arc-shaped magnets separated by spacers, and a linear guide to change the cross-sectional area of the two rings. Angular displacement between two rings causes the magnets to generate torque, which acts as a nonlinear spring. The stiffness of the joint is varied via changing the overlapping area of the magnets. The VS J exhibits nearly zero stiffness, which enables robot manipulator to be harmless to humans at a wide range of operating speed. Connected to a joint motor in series, the stiffness by the VSU and the position of the joint are controlled independently by two motors. The torque generated by the magnets is analyzed. Using dynamics of the joint, feedback linearization method is adopted to control the VSJ. In addition to feedback linearization, an integral controller is augmented in order to reduce the effect of model uncertainty and disturbances.

This paper presents design and integration of the ROBHAZ-DT3, which is a newly developed mobile robot system with chained double-track mechanisms. A passive adaptation mechanism equipped between the front and rear body enables the ROBHAZ-DT3 to have good adaptability to uneven terrains including stairs. The passive adaptation mechanism reduces energy consumption when moving on uneven terrain as well as its simplicity in design and remote control, since no actuator is necessary for adaptation. Starting from this novel design, dynamic analysis and simulation were conducted to verify the mobility of the double-track mechanism and to obtain significant design parameters such as a suitable track size and an allowable attack angle. Based on this novel mobile platform, a rescue version of the ROBHAZ-DT3 with appropriate sensors and a semi-autonomous mapping and localization algorithm is developed to participate in the RoboCup2004 US-Open: Urban Search and Rescue Competition. From the various experiments in the realistic rescue arena, we can verify that the ROBHAZ-DT3 is reliable in travelling rugged terrain and the proposed mapping and localization algorithm are effective in the unstructured environment with uneven ground.

In this paper, design and integration of the ROBHAZ-DT3 are introduced which is a newly developed mobile robot system with double tracks. It is designed to curry out military and civilian missions in various hazardous environments. The rotational passive adaptation mechanism equipped between the front and rear body enables the ROBHAZ-DT3 to have good adaptability to uneven terrain including stairways. The passive adaptation mechanism reduces energy consumption in moving on uneven terrain as well as it offers simplicity in design and teleoperation. Based on this new design concept, dynamic simulation was conducted to determine the significant parameters such as optimal track size and allowable attack angle. Also dynamic effects in vehicle turning are investigated to assess proper load torque. The ROBHAZ-DT3 system developed was successfully experimented in stair climbing case.

This paper presents a novel design of indoor airship having a passive wheeled mechanism and its stationary position control. This wheeled blimp can work both on the ground using wheeled vehicle part and in the air using the floating capability of the blimp part. The wheeled blimp stands on the floor keeping its balance using a caster-like passive wheel mechanism. In tele-guidance application, stationary position control is required to make the wheeled blimp naturally communicate with people in standing phase since the stationary blimp system responds sensitively to air flow even in indoor environments. To control the desired stationary position, a computed torque control method is adopted. By performing a controller design through dynamic analysis, the control characteristics of the wheeled blimp system have been found and finally the stable control system has been successfully developed. The effectiveness of the controller is verified by experiment for the real wheeled blimp system.