We propose a novel aerial manipulation platform, ODAR (omni-directional aerial robot), which is capable of omni-directional wrench generation with opportunistically-distributed/aligned bi-directional rotors. To circumvent tight thrust margin and weight budget of currently available rotor and battery technologies, we propose a novel design optimization framework, which maximizes the minimum-guaranteed control force/torque for any attitude while incorporating such important and useful aspects as inter-rotor aero-interference, anisotropic task requirement, gravity compensation, etc. We also provide a closed-form solution of infinite-norm optimal control allocation to avoid rotor saturation with the tight thrust margin. Further, we elaborate the notion of ESC-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: 1) separate translation and attitude control in SE(3); 2) hybrid pose/wrench control with downward force of 60N much larger than its own weight (2.6kg); and 3) peg-in-hole teleoperation with radial tolerance of 0.5mm.

This paper presents a small and lightweight tactile display system and describes its capabilities with respect to spatial and temporal tactile feedback. Each tactile display module is comprised of a 4times4 piezoelectric ultrasonic actuator array with a spatial resolution of 1.5 mm and a temporal resolution of 20 Hz. The objective of this research is to build a small and lightweight tactile display system such that the system, including the display modules and complete controller parts, will be wearable by a user. It was found that the developed tactile display module can display both spatial and temporal information with less power consumption.

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.