Indoor positioning remains an open problem, because it is difficult to achieve satisfactory accuracy within an indoor environment using current radio-based localization technology. In this study, we investigate the use of Indoor Messaging System (IMES) radio for high-accuracy indoor positioning. A hybrid positioning method combining IMES radio strength information and pedestrian dead reckoning information is proposed in order to improve IMES localization accuracy. For understanding the carrier noise ratio versus distance relation for IMES radio, the signal propagation of IMES radio is modeled and identified. Then, trilateration and extended Kalman filtering methods using the radio propagation model are developed for position estimation. These methods are evaluated through robot localization and pedestrian localization experiments. The experimental results show that the proposed hybrid positioning method achieved average estimation errors of 217 and 1846 mm in robot localization and pedestrian localization, respectively. In addition, in order to examine the reason for the positioning accuracy of pedestrian localization being much lower than that of robot localization, the influence of the human body on the radio propagation is experimentally evaluated. The result suggests that the influence of the human body can be modeled.

A hyperbolic positioning method with antenna arrays consisting of proximately-located antennas and a multi-channel pseudolite is proposed in order to overcome the problems of indoor positioning with conventional pseudolites (ground-based GPS transmitters). A two-dimensional positioning experiment using actual devices is conducted. The experimental result shows that the positioning accuracy varies centimeter- to meter-level according to the geometric relation between the pseudolite antennas and the receiver. It also shows that the bias error of the carrier-phase difference observables is more serious than their random error. Based on the size of the bias error of carrier-phase difference that is inverse-calculated from the experimental result, three-dimensional positioning performance is evaluated by computer simulation. In addition, in the three-dimensional positioning scenario, an initial value convergence analysis of the non-linear least squares is conducted. Its result shows that initial values that can converge to a right position exist at least under the proposed antenna setup. The simulated values and evaluation methods introduced in this work can be applied to various antenna setups; therefore, by using them, positioning performance can be predicted in advance of installing an actual system.

A hyperbolic positioning method with antenna arrays consisting of proximately-located antennas and a multi-channel pseudolite is proposed in order to overcome the problems of indoor positioning with conventional pseudolites (ground-based GPS transmitters). A two-dimensional positioning experiment using actual devices is conducted. The experimental result shows that the positioning accuracy varies centimeter- to meter-level according to the geometric relation between the pseudolite antennas and the receiver. It also shows that the bias error of the carrier-phase difference observables is more serious than their random error. Based on the size of the bias error of carrier-phase difference that is inverse-calculated from the experimental result, three-dimensional positioning performance is evaluated by computer simulation. In addition, in the three-dimensional positioning scenario, an initial value convergence analysis of the non-linear least squares is conducted. Its result shows that initial values that can converge to a right position exist at least under the proposed antenna setup. The simulated values and evaluation methods introduced in this work can be applied to various antenna setups; therefore, by using them, positioning performance can be predicted in advance of installing an actual system.

In this paper, a novel technique for high-accuracy indoor positioning using a GPS-compatible positioning system called IMES (Indoor Messaging System) is proposed, especially aiming to apply it to robot navigation. The radio wave propagation is modeled in order to obtain the distances between IMES transmitters and a receiver. The position of the receiver is calculated based on the principle of triangulation with those distances. In addition, an Extended Kalman filter combined with the travel distance acquired from wheel encoders of a robot is used to smooth the positioning result. The result of a positioning experiment shows that the positioning accuracy more than 1 meter is achievable without giving an initial position and direction to the robot.

Passive compliance is useful for robotic arms to ensure their safety. Often springs are used, but they are problematic because they reduce the achievable accelerations and can lead to underdamped oscillations. Torque limiters enhance the safety, but usually the torque limit cannot be adjusted to a desired torque. Electronically adjustable torque limiters, also known as series clutch actuators, have several benefits, especially for robotic arms, but they also have severe limitations. This paper suggests incorporating series clutch actuators into a gravity compensated arm. Consequently, gravity should not limit the isotropically achievable force anymore and in the case of power outage the arm keeps its position. The benefits and limitations of a series clutch actuator in a gravity compensated arm are discussed, and a prototype of such an arm is presented. Commercially available magnetic friction clutches are used. Preliminary experiments demonstrate that the safety can be increased.

Indoor positioning still remains as an open problem, for the reason that it is difficult to achieve a satisfactory level of accuracy within indoor environment, using current radio based localization technology. Thus we try to investigate the utilization of IMES radio for high accuracy indoor positioning, because of its higher resolution radio map. Signal propagation model of IMES radio has been well investigated, based on which algorithms of trilateration and extended kalman filter are developed for both static and dynamic localization of a mobile robot using IMES radio. Experiments results show that a higher localization accuracy could be achieved.

IMES is an indoor messaging and positioning system. In the present work, three methods for improving the IMES transmitter are proposed based on the result of a radio acquisition analysis: transmission diversity, a variable beamwidth antenna, and a leaky coaxial cable (LCX). The transmission diversity method increases the possibility of signal acquisition in areas with weak signal. A small-sized variable beamwidth antenna is developed to mitigate the multipath interference in narrow spaces. A field experiment with a LCX in an actual train setup is conducted to verify the effect of the LCX for the positioning of moving vehicles. The evaluation results of the proposed methods suggest their potential to be applied to practical applications.

Series elastic actuation (SEA) has been widely used for output force/torque regulation, however, the non-linearity introduced by its torsion spring hysteresis will greatly affect the quality of feedback control. Thus an experimental procedure is conducted for the modeling and identification of spring hysteresis effect, based on which a compensated control scheme is given. Experiment results show that the compensated control can improve the control performance compared with ordinary linear controller.

A new interfacing device that enables intuitive operation of a wheelchair mounted robotic arm is proposed. Three kinds of physical signals: jaw movement, breathing strength and head movement are captured using this device, and then be used to drive motion primitives of robotic arm in an intuitive way. This device is designed to operate in a mouth-only manner, thus enables usage for the upper limb disabled. Experiments are also conducted making use of this device and wheelchair mounted robotic arm to complete tasks in activities of daily living. © 2012 IEEE.

In this research, we are currently developing a 6-Dof oral Interface in order to help quadriplegic patients operate a wheelchair mounted robotic arm independently. We are focusing on building a device capable of measuring the amount of jaw's movement and respiratory pressure and changing it into electronic signals by using joysticks and air-pressure sensors. We come up with a control method which is adapted to the robot arm's 6-Dof tool coordinate system and can be used to operate the wheelchair mounted robotic arm without using hands or legs. The device can be installed instantly by connecting it to the computers with a single USB cable. The device is in a small size of 220×200×90[mm] and weighs 680[g] for compact purpose.

A new technique was developed to solve inverse kinematics based on quadratic minimization. Firstly the inverse kinematic problem was formulated as a quadratic minimization problem through the constitution of a quadratic objective function derived from quaternion based kinematic description, then a new technique is developed to solve the quadratic minimization problem. The iteration procedures of the new technique are organized in two main phases: compute the search direction based on dynamic system synthesis; seek for acceptable step along the search direction. Numerical examples showed that inverse kinematic solutions can be delivered in a robust and time-efficient way, to meet the requirements coming across in the application field of every daily living support.

In this research, we are currently developing a robotic arm which is mounted on a wheel chair to help disabled people in daily life. But it is difficult for these people to manipulate it by using a joystick. So we aim to make an automatic manipulator, and this year, we developed a robot hand which can grasp objects automatically. This time we tried 3 tasks. They are to grasp a PET bottle, a straw and a handle. To realize these tasks, this robot hand has 30[N] grip force produced with four-bar linkage system, and carries a supersonic sensor, infrared proximity sensors and pressure sensors. Finally we succeeded to create a map of environment, and to carry out them.

This paper gives an overview of OpenVR, a software tool that is able to construct a virtual robot and its working environment from CAD source files. The virtual robot can be played with the same as a real robot by providing corresponding controller and sensor interfaces, thus contribute to the research of robotics in concept visualization, robot design, and algorithm and software development. General purposed algorithms are also given to simplify the effect for the execution of complex manipulation tasks. © 2011 IEEE.

Safety issue has become the primary concern in wheelchair mounted robotic arm applications. We introduced mechanical gravity canceller in the design to realize a light weight manipulator, which also yield the greatly simplify of manipulator dynamics. Based on the simplified dynamics, sensor based contact detection can be easily implemented to enable safety. Contact reaction schemes are also applied through a impedance control law to achieve desired backdrivability. Experiments are conducted to illustrate the proposed method. ©2010 IEEE.

In order to relieve the user cognitive burden as well as time consumption of task execution for the "wheelchair mounted robotic arm" application, we proposed a "Task knowledge representation" method that is able to model a large number of tasks coming across in activity of daily livings. Based on the mathematically represented task knowledge, a "Dynamical exploring method" was applied to explore the feasible and optimal robot action sequences that are executed automatically to accomplish the task execution. An integration framework to manage the system complexity is also introduced based on the RT middleware technology. Experiment was conducted to validate our method through the execution of a robotic scenario. © 2010 IEEE.

We have developed an wheelchair mounted robotic arm system that consist of a light weight robotic arm, powerwheelchar, external sensors, and interfacing devices. In order to manage the system complexity, and build an effective and reliable integrated human in loop system based on our hardware platform, a integration architecture is proposed, which employed an "system process/service provider" integrative framework, and a a hierarchical design of system modules. The "RT Middleware" technology is adopted as the software platform for implementation issues.

In this research, we are currently developing a robotic arm which is mounted on a wheel chair to help some disabled people in daily living. The robotic arm should be safe and compact, so we installed a weight-compensating mechanism into the robotic arm to reduce its actuators' weight. And we can put away the robotic arm in storage area on the wheelchair. In this paper, newly developed robotic arm is shown. It is 7 D.O.F. Robotic arm with the weight-compensating mechanism and a simple gripper hand. It is 1070 [mm] long, and it weighs 5.05 [kg]. We confirmed 2.0 [kg] maximum load and the same height as the armrest with storage position.

Wheelchair mounted robotic arm is an assistive device designed to help physical disabled people to recover some manipulation capabilities in activities of daily livings. During task execution of wheelchair mounted robotic arm applications, both the requirement of safety and task accomplishment has to be satisfied. We have developed a wheelchair mounted robotic arm with mechanical gravity compensation, two torque sensors are mounted on the base joints to realized a sensor based active compliance control, thus a control structure is proposed to unify task oriented control and compliance control, the propsed control structure enable task execution even during an external collision. © 2010 SICE.

To help those who are using electric-powered wheelchairs, we are developing a robotic arm which is used for picking up things on the floor, scraching at their body, drinking, and so on. These helthcare devices should be developed and customized to their uses' symptoms. In consideration of those requirements, we have introduced RT middleware into the wheelchair robot system. The RT middleware is the software platform in which all functional units are composed to an 'RT-Component'. In this paper, the developed RT-components are shown in detail, and their reusability and customizability are discussed. Finally, we show that three types of RT-components which are "hardware orientedly" designed are re-used in the other projects in our laboratory.