In this paper, we present the design of two serial spherical mechanisms to substitute for a single spherical joint that is usually used to connect the platform with the base in three degrees of freedom parallel mechanisms. According to the principle derived from the conceptual design, through using the two serial spherical mechanisms as the constraint limb, several redundantly actuated parallel mechanisms are proposed for ankle rehabilitation. The proposed parallel mechanisms all can perform the rotational movements of the ankle in three directions while at the same time the mechanism center of rotations can match the ankle axes of rotations compared with other multi-degree-of-freedom devices, due to the structural characteristics of the special constraint limb and platform. Two special parallel mechanisms are selected to analyze their kinematical performances, such as workspace, dexterity, singularity, and stiffness, based on the computed Jacobian. The results show that the proposed scheme of actuator redundancy can guarantee that the redundantly actuated parallel mechanisms have no singularity, better dexterity, and stiffness within the prescribed workspace in comparison with the corresponding non-redundant parallel mechanisms. In addition, the proposed mechanisms possess certain reconfigurable capacity based on control strategies or rehabilitation modes to obtain sound performance for completing ankle rehabilitation exercise.

For reproducing the manipulation of Traditional Chinese Medicine (TCM) remedial massage and meanwhile guaranteeing safety, a 4-degree-of-freedom anthropomorphic robotic arm with integrated elastic joints is developed, and a passivity-based impedance control is used. Due to the series elasticity, integrated joints may minimize large forces that occur during accidental impacts, and, further, may offer more accurate and stable force control and a capacity for energy storage. Human expert's fingertip force curve in the process of massage therapy is acquired in vivo by a dedicated measurement device. Then three massage techniques, pressing, kneading, and plucking, are implemented by the soft arm, respectively, on torso model in vitro and on human body in vivo. Experimental results show that the developed robotic arm can effectively replicate the TCM remedial massage techniques.

This study examined the effects of communication mode (i.e., face to face versus computer mediated communication) on the instances of negotiation of meaning (NofM) and its level of noticing by learners. Sixty-four participants (32 dyads) completed two jigsaw tasks in two different mediums (one in each) and four days after the tasks they were asked to identify the instances where they had communication breakdowns in a stimulated recall protocol. The findings of the study revealed that the average number of the NofM exchanges and durations of the tasks were higher in face to face mode (F2F) but the participants of the synchronous computer mediated communication (SCMC) group noticed a higher average of NofM instances (M=10.72) compared to the F2F group (M=9.13) and the difference was significant. Based on these results, we can argue that F2F promotes a better context for the production of NofM, but the SCMC environment leads to more instances of noticing.

We consider a team of autonomous kinematically controlled non-holonomic planar Dubins car-like vehicles. The team objective is to encircle a given target so that all vehicles achieve a common and pre-specified distance from it and are uniformly distributed over the respective circle, and the entire formation rotates around the target with a prescribed angular velocity. The robots do not communicate with each other and any central decision-maker. The sensing capacity of any vehicle is heavily restricted: It has access only to the distance to the target and to the distances to the companion vehicles that are in a given disc sector centered at the vehicle at hand; no robot can distinguish between its companions, and does not know their parameters. A distributed control law is proposed, and mathematically rigorous proofs of its non-local convergence as well as collision avoidance property are presented. The performance of the control law is illustrated by computer simulations and experiments with real robots.

This paper presents research findings of a longitudinal empirical case study that investigated an innovative Computer Assisted Language Learning (CALL) professional development program for pre-service English as Foreign Language (EFL) teachers. The conceptualization of the program was based on the assumption that pre-service language teachers learn better in situated contexts (Egbert, 2006). Therefore, a key component of the program was the development of school-based research projects, in which the student teachers needed to design, implement, and evaluate technology-enhanced EFL lessons in collaboration with in-service teachers. Data were collected via field notes, video recordings of lessons, academic research reports produced by the pre-service teachers, and in-depth interviews with the pre-service and in-service teachers. Our findings indicate that the field experiences provided professional learning opportunities that supported the student teachers’ development as CALL practitioners. The participating pre-service teachers especially emphasized the important role played by school-based experiences in allowing them to use technology in authentic language teaching scenarios and to evaluate the impact of technology on language teaching and learning. The paper concludes with a discussion of important principles and guidelines that should underlie and inform such collaborative efforts and a summary of the implications of the findings for the design of CALL pre-service teacher education programs.

We propose a wireless power distribution system (WPDS) operating at 2.45 GHz CW in buildings instead of wired power distribution in order to reduce the initial cost of the building. Required technologies for the WPDS are (a) low-cost and low-loss deck plate waveguide, (b) variable microwave power distributor for the waveguide, and (c) high-power (>100 W) rectifier at the outlet. We developed and tested the deck plate waveguide, power distributor, and high-power rectenna consisting of 256 Si Schottky barrier diodes and newly developed GaN diodes. Finally, a test WPDS was built and microwave power transmission experiments were conducted. The total efficiency of the test WPDS was estimated to be 52%.

The wireless efficiency of the strongly coupled magnetic resonance (SCMR) method greatly depends on the Q-factors of the TX and RX resonators, which in turn are strongly dependent on the geometrical parameters of the resonators. This paper analytically derives the equations that can be used to design optimal spiral resonators for SCMR systems. In addition, our analysis illustrates that under certain conditions globally maximum efficiency can be achieved.

This paper is dedicated to the extensive review of state-of-the-art contactless energy transfer (CET) systems that are gaining increasing interest in the automatic machinery industries. We first introduce the circuit equivalent networks considered in the literature, and discuss the main operating principles. Possible circuital resonant solutions are also discussed together with the required compensating networks. Then we focus on the problem of transferring, at the maximum efficiency, high-power levels (of the order of 1 kW or higher), showing that highly coupled inductive links are needed, requiring to refrain from the resonance condition. These systems are usually referred to as CET systems, since the link distances are negligible with respect to the coils dimensions. The operating frequencies are of the order of tens to hundreds of kilohertz. The fundamental figures of merit are analytically defined and used to measure the actual limitations involved in this class of systems, including aspects related to realization feasibility with respect to voltages and currents limitations. Finally, state-of-the-art CET works are surveyed, and realistic applications for different operating frequencies are considered and critically compared.

In this paper, a hybrid solar/electromagnetic (EM) energy harvester that operates at 2.45 GHz is presented. The proposed harvester integrates the solar cells in the same area as the rectenna element obtaining a compact implementation. The radiating element that forms part of the rectenna is a cavity-backed slot antenna based on substrate-integrated waveguide technology, which allows for a compact, single substrate implementation. The radiating element is connected to a circuit that provides both the rectification of the incoming EM signals and the collection of DC energy coming from solar cells. A single-substrate prototype has been implemented, demonstrating an overall power conversion efficiency up to 30%, depending on the incoming radio frequency signal level and the ambient light conditions.

To date, the technique of inductive power transfer has found applications in industry including two-dimensional battery charging. However, this restricts any load to planar movements. This paper proposes custom designed magnetic structures of a loosely magnetically coupled three-dimensional inductive power transfer system. This is done via computational software utilizing the finite-element-method. More specifically, single-phase and multi-phase primary magnetic structures are proposed to distribute a power transfer window along three orthogonal axes. Next, a secondary magnetic structure is custom designed to induce electromotive force in three-dimensions. The proposed system is simulated to demonstrate power transfer for charging an AA-battery cell. Finally, the thermal effects upon the secondary load are considered.

This paper addresses low-power, low-voltage electronic circuit requirements for wireless sensors with energy harvesting. The challenges of start-up for micro-controller unit (MCU)-based energy-harvesting platforms is discussed where a transient, low-voltage (20–1000 mV), low-power (<100 μW) source having a relatively high source impedance (possibly >500 Ω) is used. Efficient converter circuitry is required to transform the low-voltage output from the source to a level suitable for typical electronic devices, 1.8–5 V, and a prototype is demonstrated in the paper. Owing to the limited energy available to deliver to the storage element, the converter output voltage typically has a slow rising slew rate that can be a problem for MCUs. This necessitates a reset circuit to hold-off operation until a level high enough for reliable operation is achieved. Once operational, Maximum Power Point Tracking (MPPT) extracts peak power from the harvester while simultaneously tracking the transient nature of the source. In this low-power application, MCU programming needs to be efficient, while otherwise keeping the MCU in the lowest power standby mode possible to conserve energy. In a fully integrated design, a single MCU may be used for the sensor application, power management, power conversion, and MPPT functions.

Magnetic-resonant wireless power transfer (MRWPT) has been typically realized by using systems of coupled resonators. In this paper, we introduce a rigorous network modeling of the wireless channel and we introduce several viable alternatives for achieving efficient MRWPT. Ideally, the wireless channel should realize a 1:n transformer; we implement such transformer by using immittance inverters. Examples illustrate the proposed network modeling of the magnetic-resonant wireless power channel.

We propose a fuzzy weighted subtask controller for a redundant robot manipulator. To expand the feasibility of the inverse kinematic solution, we introduce a weighted pseudo-inverse that changes the null-space of the Jacobian. The weights of elements in the pseudo-inverse are obtained using fuzzy rules that are related to the null-space velocity tracking error. With the pseudo-inverse, we develop a task space controller to track a desired task space trajectory and subtask control input. We propose a weighted subtask controller for multiple subtasks. The results of a simulation and experiment using a seven-degree-of-freedom whole arm manipulator robot show the effectiveness of the proposed controller with multiple subtasks.