Sousuke Nakamura

Wheeled robot with movable center of mass for traversing over rough terrain

Planetary exploration requires rovers to perform a variety of challenging tasks autonomously. In order to complete relevant scientific mission, these rovers need to overcome difficulty for rough terrain traversing by online methods. This paper discusses an idea that utilizes a rover mobile center of mass in order to aid in traversing rough terrain. According to vehicle pitch angle and contact angles, the rover recalculates the optimal position for the center of mass to minimize the indicator defined by two factors : the wheel driving force over the wheel normal force (adhesion coefficient) and tip-over stability angle (stability coefficient). Two innovative approaches are developed in this paper. The first one is that the authors defines easily comprehensible two factors, adhesion and stability coefficients for traversability indicator and proposes a method to calculate optimal center of mass position. The second one is that in the case of four-wheels drive, the relation between the front wheel and the rear wheel adhesion coefficient is easily solved and the best case for giving the driving forces can be solved as force making the front and the rear wheel adhesion coefficient equal. The authors call this optimal force distribution method. Finally, this paper shows some simulation results for traversing rough terrain that compute the optimal center of mass while traversing the terrain.

Error Characteristics of Passive Position Sensing via Coupled Magnetic Resonances Assuming Simultaneous Realization With Wireless Charging

Recently, wireless charging via coupled magnetic resonances has gained attention because it offers the possibility of efficient midrange wireless charging. However, recent studies have shown that the use of a position sensor is helpful in realizing efficient power transmission. In response, we have proposed a passive position sensing method that shares a common structure with a wireless charging system, enabling cost reduction, and space reduction because of integration of multiple functions into a single system and batteryless and cost-effective transponders because of passive sensing. The sensing method is useful for efficient wireless charging or even long-range navigation for mobile robots such as automated guided vehicles. However, the error characteristics of the sensor have not been previously studied. Therefore, the error characteristics of the position sensing were derived through error analysis in this paper. Moreover, the first actual experiment of 3-D position estimation was conducted to demonstrate the appropriateness of the position sensing method and to analyze the error characteristics.

Research on Updating of Body Schema Using AR Limb and Measurement of the Updated Value

The body schema, an internal model in the brain used to recall the body position, is known to be updated by adapting to the changes in the body figure due to the body growth. Furthermore, the recent research has reported the active updating of the body schema by misunderstanding ones body position using the illusion phenomenon. However, the current method of actively updating the body schema has limited effects and does not handle selective updating of each body part. Therefore, in this paper, a new method using an augmented reality (AR) limb is proposed for the selective updating of unitary parts of the body image in a short period of time. The AR limb is the virtual limb composed by actively extendable and retractable parts, projected by head-mounted display. The basic concept is that the body schema is updated to match the extended and retracted part of the AR limb based on the body schema learning mechanism in the sensory integration of visual and somatic information. The potential effectiveness of the method was verified by actual experiment applying the body schema update to the right forearm.

Basic study of magnetic resonance coupling-based distance sensor with adjustable sensing range using active quality factor control

Recently, various types of mobile robots have clearly gained attention and some are readily available. In response to this, the authors have been studying on the system which provides both power and self-position : the essential quantities for the mobile robot, by single non-restraint device. The proposed system realized the wireless power transmission and position sensing simultaneously using magnetic resonance coupling. However, due to the fact that sensing range depends on the fixed quality factor of antenna, the narrow sensing range of the current system was a problem in the practical use. Therefore, the authors are considering a new approach which enables the control of the sensing range by active quality factor control. In this paper, the system configuration, basic theories and circuit analysis results of the active quality factor control approach are introduced.

Q Controllable Antenna as a Potential Means for Wide-Area Sensing and Communication in Wireless Charging via Coupled Magnetic Resonances

Recently, wireless charging via coupled magnetic resonances gains attention because it has a potential of efficient mid-range wireless charging. Here, functions such as sensing at the transmitter and wireless communication from the target are the essential elements to realize the standard wireless charging system. Currently, the sensing and communication protocol of hardware (i.e., high-frequency power source and antenna configuration) compatible with wireless charging is gaining attention in terms of cost and space reduction due to the use of common components in multiple functions. However, these protocols have the problem of narrow effective areas. Therefore, this paper presents a method for wide-area sensing and communication with slight modification of the configuration. The basic concept is to expand the effective area related to antenna Q factor by using the Q controllable antenna acting as though the Q factor increased. The underlying theory was described with electric circuit theory. The experimental results showed that the Q factor can be increased until the resonance collapses, and the increase of Q factor has the potential to widen the effective area of sensing and communication.

Preliminary development of an Energy Logistics as a new wireless power transmission method

In recent years, various types of wireless power transmission method have been proposed. However, assuming the mobile devices in the living space as a target, the traditional methods seem to be ineffective. The only wide range transmission method based on electro-magnetic wave has the problem of the safety to humans, while the effective range of the other transmission methods are too short. Therefore, a new wireless power transmission method called Energy Logistics is proposed in this paper. The method realizes safe and wide range power transmission by the combination of mid-range energy coupling technique and energy delivery robot. The energy delivery works as a substitute for power cable between the power source and the mobile devices, while the energy coupling is used for connecting power source and energy delivery robot or energy delivery robot and mobile device. Basic characteristics of mid-range wireless charging for lithium-ion battery via magnetic resonance coupling is derived since it is the challenging task in the Energy Logistics. Furthermore, some approach for increasing the transmission efficiency together with realizing the suitable charging power and voltage is discussed.

The concept, configuration and operation procedure of the energy management system for mobile devices via Wireless Charging Robot

In recent years, energy management of the mobile device is researched in two approaches; energy saving and energy charging. In terms of energy charging, though the wireless charging and the energy harvesting technologies have been proposed, these technologies could not satisfy all of the criteria; location-free, connection-free, reliable and human-safe. In response, the authors are proposing a new energy management method for mobile device based on the Wireless Charging Robot (i.e., mobile robot with wireless charging function via magnetic coupled resonances). It operates in the combination of two charging tasks; charging the mobile device from robots (i.e., mobile device charging task), and charging the robot from charging stations connected to power system (i.e., self charging task). In this manner, robots mediate the energy delivery from the power system to the mobile devices, and consequently, the system satisfies all of these criteria. This paper introduces the concept, configuration, operation procedure and developmental results of some functions.

Prototype design of energy management system for mobile device via Wireless Charging Robot

In recent years, energy management of the mobile device is researched in two approaches; energy saving and energy charging. In terms of energy charging, though the wireless charging and the energy harvesting technologies have been proposed, these technologies could not satisfy all of the criteria; location-free, connection-free, reliable and human-safe. In response, the authors are proposing a new energy management method for mobile device based on the Wireless Charging Robot (i.e., mobile robot with wireless charging function via magnetic coupled resonances). It operates in the combination of two charging tasks; charging the mobile device from robots (i.e., mobile device charging task), and charging the robot from charging stations connected to power system (i.e., self charging task). In this manner, robots mediate the energy delivery from the power system to the mobile devices, and consequently, the system satisfies all of these criteria. This paper introduces the abstract architecture and procedure of the overall system with the basic method for designing the wireless charging function in the energy management system.

Physiological estimation of body balance for Affinitive Personal Vehicle

Recently, personal vehicles have received a lot of attention to expand our mobility for low carbon society and diversification of individual mobility. So far several small vehicles have been developed. However a new thesis of designing and controlling personal vehicles is required, because there are some difference between general vehicle-used environment and personal vehicle-used environment like mixed traffic. In such new kinds of environment, vehicles should have close relationship with drivers. To have closer relationship, personal vehicles must be smaller and lighter. In addition, designing personal vehicles motion by considering drivers psychological evaluation, we can provide more comfortable vehicles interface. The author defined these kinds of personal vehicle as Affinitive Personal Vehicle and focused on drivers sense of balance to estimate drivers psychological evaluation. In this paper, author shows that change of vehicles motion effects on drivers sense of balance, and there is relation between drivers sense of balance and Kaisei evaluation.

Reduction of phase shifting for range expansion in magnetic resonance coupling-based distance sensor with adjustable sensing range

The realization of wireless charging and self-localization as an integrated compact system using magnetic resonance coupling is useful as an application for mobile robots. However, the narrow sensing range, due to the fact that the sensing method is categorized as passive sensing, was a problem in the practical use. Thus, the method which enables control of the sensing range by virtually adjusting the quality factor of the antenna is proposed as a solution. However, the phase shifting error made it difficult to maintain the resonance status in case of high-Q. Thus, this paper introduced the redesigned configuration of the quality factor control circuit. The configuration enabled the dramatical increase of Q up to 30 times the original value, which is expected to extend the sensing range to two times and reduce the number of arrayed transmitter antenna to one fourth.