Through the efforts of robotic engineers and inspired by the flapping flight of smaller creatures (e.g., insects and hummingbirds), the untethered stable hovering of flapping micro-aerial vehicles (FMAVs) has been achieved. Now, engineers are evaluating how to improve the mobility of these vehicles. The maneuverability of insects and birds in flight, such as their sharp turns and their takeoffs and landings from vertical walls, is what researchers originally expected from FMAVs. However, in previous studies, just one active (or one active plus one passive) degree of freedom (DoF) was given to the main actuation of the wing, and the range of movement of the wings was small. In addition, the magnitude of the attitude control torque that could be generated was relatively small when compared with multi-rotors. However, with the recent developments of small motors and drive-circuit technology, the realization of untethered flight by FMAVs equipped with four or more motors seems possible. This study utilized numerical calculation to investigate the advantage of a flapping-flight robot equipped with two pairs of left and right wings capable of stroke and twisting movements with two independent DoFs ($2\times 2$-DoF FMAV). The results of the numerical studies confirmed that, compared with the split-factor method widely used in past studies, the$2\times 2$-DoF FMAV can generate higher yaw torque without the need for additional large driving torque. This shows that various agile flight functions are possible.

A unidirectional ultrasonic motor (USM) is applied to the thorax unit of a flapping micro aerial vehicle (MAV) with the aim to develop an MAV in the 10-gram-range, for which appropriate DC motors with high power-weight ratios are unavailable. As a trial, a unidirectional USM having an ultrasonic transducer with mass of 336 mg and rotor of 3 mm diameter is implemented to a belt drive mechanism in place of a DC motor and spar gear unit. At no load and without wings, the USM works well and achieves a flapping frequency exceeding 32 Hz, while the output power is around 36 mW owing to the mismatch of the two vibration modes that dominate the efficiency of the USM. Although the observed lift force remains low because of the lack of USM power and heaviness of the wings, the appropriateness of the mechanical design is confirmed and improvements toward the 10-gram-range flapping MAV with USM are discussed on the basis of these results. Another actuation mechanism of the flapping MAV is proposed.

A parallel-processing method, named “critical data-aware operation” (CDO), for higher energy efficiency (i.e., lower energy consumption in computer systems) is proposed. The proposed method achieves energy-efficient computation by aggressive voltage scaling with critical data-protection techniques. As a case study to evaluate the method, K-means clustering simulation was performed, and the simulation results show that the method achieves 23% better energy efficiency (with negligible accuracy degradation) than the conventional method.

This paper investigates the hovering efficiency of the wing-actuation parameters of a flapping microaerial vehicle with a two-degree-of-freedom (2-DOF) driving mechanism, using finite-element analysis based on the arbitrary Lagrangian-Eulerian method (ALE-FEA). A 75-mm-long wing and multilinkage mechanism that consisted of thin plates and films was employed. It generated a flapping motion that consisted of horizontal stroke of the wing and twist around its leading edge, which were activated by the rotations of two motors. The application of the ALE-FEA was successfully extended to the structural behavior of the driving mechanism. The behaviors of the linkage mechanism, the wing, and its surrounding airflow were reproduced numerically. Various parameters were obtained, some of which were difficult to measure in real experiments, such as the pressure distribution on the wing. For cases of 25 combinations of wings' twist angles and flapping periods, lift forces and energy requirements for the motors were determined. Based on these results, the most efficient flapping combination that generated 1 gf lift force was calculated. In contrast with the combination that created the strongest lift force, the combination of a larger twist angle and a faster flapping cycle was found to provide the most efficient flight.

This paper describes a sub 100-mW H.264/AVC [email protected] integer-pel motion estimation processor core for a low power video encoder. It supports macro block adaptive frame field (MBAFF) encoding and bi-directional prediction for a resolution of 1920times1080 pixels at 30 fps which haven't been realized by conventional methods. The proposed processor core features a novel hierarchical algorithm, a reconfigurable ring-connected systolic array architecture, and a segmentation- free rectangle-access search window buffer. The processor core has been designed in a 90 nm CMOS technology, and its core size is 2.5times2.5 mm2. With one core, one reference frame can be handled, and 48 mW is consumed at 1 V. Two-core configuration dissipates 96 mW for two reference frames.

An actuator for a middle-sized flapping flight robot is quantitatively investigated. Flapping flight like that of insects is a potentially useful method of travel for micro robots. Some insect-mimicking robots have been developed, which have actuators with two or more degrees of freedom per wing. For the detailed design of such an actuator, it is necessary to deal with the interaction between the behavior of the actuator and the aerodynamic forces generated by the actuation. In particular, the torque and power requirements of each degree of freedom are essential in the choice of a suitable motor, but it is impossible to determine these without considering the interaction between the driving force of the actuator and the reaction force of the wing from the surrounding airflow. Here, we achieved an analysis of the mechanical aspects of flapping flight, actuator and wing, using finite element analysis based on the arbitrary Lagrangian-Eulerian method, which can treat the fluid-structure interaction problem properly. We worked out the spec of motors for the 2DOF actuator, and investigated the structural tolerance. We developed a useful tool for the design of flapping flight robots

For super-parallel video processing, we proposed a power- and area-efficient SRAM core architecture with a segmentation-free access, which means accessibility to arbitrary consecutive pixels, and horizontal/vertical access. To achieve these flexible accesses, a spirally-connected local-wordline select signal and multi-selection scheme in wordlines are proposed, so that extra X-decoders in the conventional multi-division SRAM can be eliminated. Consequently, the proposed SRAM reduces an area and power by 69% and 59%, respectively, when it is applied to a 128 parallel architecture. The proposed 160-kbit SRAM with 16-read ports (eight-division and 2-read port SRAM) is implemented to a search window buffer for an H.264 motion estimation processor core which dissipates 800 muW for QCIF 15-fps in a 130-nm technology

We investigated some configurations of middle-size and high-aspect ratio wings for flapping flight by fluid-structure interaction simulation. Mimicking the flapping flight of insects is a useful method of microrobot motion. Its comprehensive unsteady aerodynamics has gradually been unraveled and several types of flapping-flight robots have been proposed. We examined the motion of a dragonfly, and try to apply it to microrobots. In designing such nimble flapping flight, adequate evaluation of the deformation of the wing is unavoidable. Wings of such species have high aspect ratio because a small momentum of inertia around the longitudinal axis is a great advantage in controlling. Such a slender wing is easy to twist around the longitudinal direction. Thus, in order to design such a wing, the wing behavior caused by interaction with the airflow must be analyzed, and the adequate stiffness must be determined. We designed two types of wings based on the architecture of the dragonfly’s wing, and examined the performance of the wings by fluid-structure interaction analysis. Here we show some examples of the designs and the performance of the wings for hovering, as the results of the first trial.

An insect's flapping flight is an attractive method of transportation. It shows many useful flight modes such as maneuverable turning and stable hovering. In recent studies, experimental methods and numerical simulations have been successfully applied to solve the mechanism quantitatively. However, it is extremely difficult to accurately estimate the deformation of the wing caused by interaction with airflow. In prior studies, we analyzed this problem using a novel numerical simulation, fluid-structure interaction analysis, in order to represent this interactive behavior accurately, and achieved the quantitative evaluation of dragonfly hovering with flexible wings. As an advanced analysis, we added a solution of the interaction between the body and wings to the method, and realized free-flight simulation. Here, we demonstrate a sharp turn of 10 rad/s in a numerical simulation using a model based on an actual dragonfly.