Mobile robot positioning in an indoor environment via fingerprinting technique is made by matching the unknown WiFi data to a spatial WiFi power map database. In past years, this technique has gained reasonable accuracies in the cost of high labor yielded for the database. Thus, automatic database construction by means of interpolating missing data is desired. This paper described a variation of Inverse Distance Weight (IDW) interpolation which is the Modified Shepard's Method (MSM) for our medical-oriented mobile robot - Terapio. By properly selecting the reference locations, we found that this method is better than the conventional IDW method and comparable to the recently popular Kriging interpolation algorithm in an indoor environment by employing the state-of-the-art WKNN positioning algorithm.

Holonomic omnidirectional mobile robots are useful because of their high level of mobility in narrow or crowded areas, and omnidirectional robots equipped with normal tires are desired for their ability to surmount difference in level as well as their vibration suppression and ride comfort. A caster-drive mechanism using normal tires has been developed to realize a holonomic omnidiredctional robot, but some problems has remain. Here we describe effective systems to control the caster-drive wheels of an omnidirectional mobile robot. We propose a Differential-Drive Steering System (DDSS) using differential gearing to improve the operation ratio of motors. The DDSS generates driving and steering torque effectively from two motors. Simulation and experimental results show that the proposed system is effective for holonomic omnidirectional mobile robots.

Transfer of container filled with liquid may generate sloshing, considered an undesirable effect in many systems. This research explores the use of input shaping technique to suppress sloshing on transfer of liquid container using multi-joint robot arm. By input shaping principle, acceleration command is shaped using two impulses in such a way to cancel each other's response. Position trajectory is then translated as joint angles trajectory, which is then fed to Mitsubishi PA10-7C robot arm. Simple pendulum model with damping element is applied to analyze sloshing phenomena. Experimental results show that the employed input shaping technique reduces sloshing during and after container transfer.

This paper proposes an intelligent massage control system by using multi-fingered robot hand with hybrid impedance control, which is able to create the movement and the force of robot such as the human's massage. Therefore, the various massage points, such as the change of the stiffness of human skin muscle, can be controlled by using impedance control method. The hybrid impedance control is comprised of the two methods of the position-based and the force-based impedance control were applied. The position-based impedance control is used to control the lateral position of massage on the human skin muscle. On the other hand, the force-based impedance control is used to control the force of the vertical direction on human skin muscle. This paper also gives the identification of human skin muscle through robot perception of impedance to decide the parameter of impedance controller. The control strategy using impedance control to implement an adaptive control system is presented, when human condition is changed with soft and hard skin muscle. Effectiveness of massage control system by using multi- fingered robot hand with hybrid impedance control is demonstrator through actual massage experiments of pushing and rubbing motion.

This paper proposes an intelligent massage control system by using multi-fingered robot hand with hybrid impedance and force control, which is able to create the movement and force of robot to behave as similar as the human’s massage. Therefore, the various massage points, such as the changing of hardness and softness of human skin muscle condition, can be appropriately controlled by using hybrid impedance and force control method. The impedance control is used to control the lateral position of massage on the human skin muscle. The perpendicular direction one, while force control is carried out for the vertical direction on human skin muscle. This paper also gives a modeling of human skin muscle through robot perception of impedance to decide the parameter of impedance controller. The control strategy using a hybrid impedance and force control to implement an adaptive control system is presented, when human condition is changed with soft and hard skin muscle. For the robot fingertip force, PI servo compensation is used together with impedance control. Based on using both impedance and PI servo compensation, the effectiveness of the massage position and force control is shown through actual massage motion experiments.

In this paper, riding comfort of an omnidirectional wheelchair (OMW) driven by joystick is studied for the case when OMW moves in X direction, Y direction, or in a slanting direction. In order to achieve the comfort driving specific spectrum elements such as natural frequency of OMW and discomfort frequency of human organs are suppressed. In order to evaluate the comfort, a human model which considers human upper body composed of two parts: torso and head, has been developed and used in order to test the effectiveness of the proposed approach. Experimental results of velocity control are shown.

An omni-directional wheelchair is highly maneuverable in narrow or crowded areas such as residences, offices and hospitals. However, with the increase in the degrees of freedom accompanying omni-directional wheelchairs, it has become more important than in the past to develop a smooth and vibrationless motion control system. This paper presents a novel motion control method for an omni-directional wheelchair considering the suppression of vibration of both the wheelchair and the user. In the proposed control system, the vibration of the wheelchair is suppressed by notching the frequency characteristics at the natural frequency of both the wheelchair and human's organs. The designed controller satisfies various control specifications such as settling time and stability by using feedback from only the wheelchair's position data. The effectiveness of the proposed system is evaluated by the output signal of a sensor attached to the wheelchair and by a descriptive inspection of several users.

The present paper gives a haptic feedback control of a holonomic omni-directional mobile wheelchair (OMW) with a haptic joystick for the operation of disable people or elderly people considering not only the navigation task but also user's comfort and safety. In the present research a haptic joystick was designed and applied with being maneuverable for users and free of joystick's vibrations. If an obstacle is detected in the direction of movement, the impedance of the joystick in this direction is changed. Namely, the closer the obstacle is the bigger the impedance value becomes. By this function, users spontaneously understand that they are in risk of obstacle collision and then users can change the direction of movement, by their decision, in order to avoid it. Furthermore, for the command input by human joystick operation, velocity control of OMW is executed by means of frequency shaped control to achieve the comfort drive for users. The proposed approach is thought to be reasonable as a man-machine existing control system.

In this paper, a novel power assist system for the attendant of an omni-directional transport wheelchair is proposed. The input force of the attendant is measured using a force sensor attached to the handle of the wheelchair. The desired motion of the wheelchair is estimated from the output signal of the force sensor using fuzzy reasoning. Then, it is transmitted to four motors of the wheelchair to make it move toward the desired direction. The effectiveness of the proposed method is examined by simulations and experiments.

This paper presents a massage motion control system comprised of position control and force control in a multi-fingered robot hand. By making use of an algorithm which converted the desired fingertip trajectory into the desired angle of links in each finger by means of inverse kinematics, the finger position control from the initial position of the multi-fingered robot hand to a target position of the objects for massage was achieved. Its controller was used until the robot hand contacted the objects for massage. After contact was made, the fingertip position control was switched to a force control position needed to apply pressure for the massage. The fingertip forces exerted by an expert human therapist was measured using sheet distribution pressure sensors, and the data obtained was recorded in a computer. After the measurements were taken, the human expert's fingertip force was reproduced by the robot hand. The fingertip force of the robot hand was controlled using feedback obtained with a 6-axis force sensor. To make the force of each fingertip of the four-fingered robot hand track to the fingertip force exerted by the expert human massage therapist, PI servo compensation and a Jacobian matrix were really applied for the human's shoulder. Through simulation and experiments, the usefulness of the proposed control systems was demonstrated.

An omnidirectional wheelchair is highly maneuverable in narrow or crowded areas such as residences, offices and hospitals. A semi-autonomous control method for omnidirectional wheelchairs is proposed. In addition to allowing the normal joystick commands of the wheelchair operator, this method provides a collision avoidance function using external sensors. The proposed method does not employ unexpected autonomous movements conflicting with the operator's joystick commands, because this tends to create discomfort for users and can be dangerous for infirm patients. Instead, the proposed method merely alerts the operator to the presence of an obstacle; this is accomplished by changing the impedance of the joystick essentially creating resistance against moving the joystick in the dangerous. direction. The wheelchair's motion remains controlled only by the operator's joystick commands, while a collision is avoided successfully. The effectiveness of the proposed method is shown by experiments with an onmidirectional wheelchair.