We propose a novel aerial manipulation platform, an omnidirectional aerial robot, that is capable of omnidirectional wrench generation with opportunistically distributed/aligned Sectional rotors. To circumvent the tight thrust margin and weight budget of currently available rotor and battery technologies, we propose a novel design optimization framework, which maximizes the minimumguaranteed control force/torque for any attitude while incorporating such important and useful aspects as interrotor aerointerference, anisotropic task requirement, gravity compensation, etc. We also provide a closed-form solution of infinity-norm optimal control allocation to avoid rotor saturation with the tight thrust margin. Further, we elaborate the notion of electronic speed controller induced singularity and devise a novel selective mapping algorithm to substantially subdue its destabilizing effect. Experiments are performed to validate the theory, which demonstrate such capabilities not possible with typical aerial manipulation systems, namely, separate translation and attitude control on SE(3), hybrid pose/wrench control with downward force of 60 N much larger than its own weight (2.6 kg), and peg-inhole teleoperation with a radial tolerance of 0.5 mm.
Thermal cues provide information about the thermal properties of an object held in the hand. These cues can be simulated in a thermal display and used to assist in identifying the object. Two experiments were conducted using a thermal display that simulated the cues associated with contact with different materials. The thermal contact model was based on a semi-infinite body model that included thermal contact resistance and blood perfusion. Its performance was evaluated in two experiments, the first of which involved discriminating between simulated materials, and in the second, subjects were required to identify simulated materials based on the thermal cues presented to one, three, or five fingers. The results from the first experiment indicated that when the temperature profile associated with contact with a real material is presented to the finger, subjects can use this cue to discriminate between simulated materials. Their performance on this task is comparable to that achieved with real materials with similar thermal properties. In the second experiment, the accuracy with which subjects identified a simulated material based on thermal cues improved as the number of fingers stimulated increased, suggesting that spatial summation of cold occurs when the area stimulated is noncontiguous. However, most of the improvement in identifying materials occurred when the display presented thermal cues to three as compared to one finger, with little further enhancement in performance when five fingers were stimulated. These results indicate that thermal displays can be used effectively to present information about the material composition of objects in virtual environments.
This paper presents a multi-agent robotic fish system used for mariculture monitoring. Autonomous robotic fish is designed to swim underwater to collect marine information such as water temperature and pollution level. Each robotic fish has 5 degrees of freedom for controlling its depth and speed by mimicking a sea carp. Its bionic body design enables it to have high swimming efficiency and less disturbance to the surrounding sea lives. Several onboard sensors are equipped for autonomous 3D navigation tasks such as path planning, obstacle avoidance and depth maintenance. A robotic buoy floating on the water surface is deployed as a control hub to communicate with individual robots, which in turn form a multi-agent system to monitor and cover a large scale sea coast cooperatively. Both laboratory experiments and field testing have been conducted to verify the feasibility and performance of the proposed multi-agent system.
The spatial characteristics of thermal perception were studied in two experiments that examined how thermal stimuli are processed within the hands. A thermal display that simulates cues associated with making contact with different materials was used in these studies. In the first experiment, participants indicated which of two simulated materials that were presented to the index fingertip was cooler. The results indicated that participants were unable to resolve the two areas of thermal stimulation. In the second experiment, the effects of concurrent thermal stimulation on the ability to discriminate between simulated materials were evaluated. Thermal cues were presented to the middle fingers of both hands and to two adjacent fingers on one hand. Thermal spatial summation was evident across the fingers, which enhanced the ability to discriminate between materials when the cooler stimulus was presented to three fingers. When the same stimulus was presented to the two hands, the stimulation of adjacent fingers altered the perceived thermal response.
This paper proposes a wing root control mechanism inspired by the drag-based system of a dragonfly. The previous mechanisms for generating wing rotations have high controllability of the angle of attack, but the structures are either too complex or too simple, and the control of the angle of attack is insufficient. In order to overcome these disadvantages, a wing root control mechanism was designed to improve the control of the angle of attack by controlling the mean angle of attack in a passive rotation mechanism implemented in a simple structure. Links between the proposed mechanism and a spatial four-bar link-based flapping mechanism were optimized for the design, and a prototype was produced by a 3D printer. The kinematics and aerodynamics were measured using the prototype, a high-speed camera, and an F/T sensor. In the measured kinematics, the flapping amplitude was found to be similar to the design value, and the mean angle of attack increased by approximately 30° at a wing root angle of 0°. In the aerodynamic analysis, the drag-based system implemented using the wing root control mechanism reduced the amplitude of the force in the horizontal direction to approximately 0.15 N and 0.1 N in the downstroke and upstroke, respectively, compared with the lift-based system. In addition, at an inclined stroke angle, the force in the horizontal direction increased greatly when the wing root angle was 0° at the inclined stroke angle, while the force in the vertical direction increased greatly at a wing root angle of 30°. This means that the flight mode can be controlled by controlling the wing root angle. As a result, it is shown that the wing root control mechanism can be applied to the MAV (micro air vehicle) to stabilize hovering better than the MAV using a lift-based system and can control the flight mode without changing the posture.
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