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An experimental telerobotics (TR) simulation is described suitable for studying human operator (H.0.) performance.Simple manipulator pick-and -place and tracking tasks allowed quantitative comparison of a number of calligraphic display viewing conditions. The Ames -Berkeley enhanced perspective display was utilized in conjunction with an experimental helmet mounted display system (HMD) that provided stereoscopic enhanced views. Two degree -of-freedom rotations of the head were measured with a Helmholtz coil instrument and these angles used to compute a directional conical window into a 3 -D simulation.The vector elements within the window were then transformed by projective geometry calculations to an intermediate stereoscopic display, received by two video cameras and imaged onto the HMD mini -display units (one -inch CRT video receivers) mounted on the helmet.An introduced communication delay was found to produce decrease in performance. in considerable part, this difficulty could be compensated for by preview control information. That neurological control of normal human movement contains a sampled data period of 0.2 seconds may relate to this robustness of H.O. control to delay.A number of control modes could be compared in this TR simulation, including displacement, rate an 3cceleratory control using position and force joysticks.A homeomorphic controller turned out to be no better than .joysticks; the adaptive properties of the H.O. can apparently permit quite good control over a variety of controller configurations and control modes. Training by optimal control example seemed helpful in preliminary experiments.

SYNOPSISUV-curable polyurethane acrylates for poly(viny1 chloride) (PVC) floor coating were prepared using nonyellowing polyisocyanates. The effects of the chemical structure of the polyisocyanates and hydroxyacrylates, and the compositions of the prepolymer/diluent on the properties of the UV-curable polyurethane acrylates were investigated. Several different urethane acrylate prepolymers from four different polyisocyanates, isophorone diisocyanate (IPDI) adduct, hexamethylene diisocyanate (HDI) adduct, HDI biuret, and HDI isocyanurate, and two different hydroxyacrylates, hydroxypropyl acrylate (HPA), polycaprolactone modified hydroxyethylhexylacryylate (PCMHEA). UV-curable coating materials were formulated from the prepolymers and 1-hydroxycyclohexylphenyl ketone as a photoinitiator with polyethylene glycol diacrylate (PEGDA) as a diluent. The polyurethane acrylates prepared with HDI isocyanurate and the equimolar mixture of HPA and PCMHEA showed balanced coating properties such as tensile properties, hardness, weatherability, and good adhesion. The dynamic mechanical studies showed the properties of those polyurethane acrylates were well correlated with their glass transition temperature behaviors. It was also found that the adhesion was best as a PVC floor coating with the appropriate viscosity (below 150 P a t 25OC) when 35% PEGDA as a diluent was used.

As data rates supported by the physical layer increase, PHY and especially MAC overheads increasingly dominate the throughput achievable by wireless networks. A promising approach for reducing these overheads is to aggregate a number of frames together into a single transmission. The 802.11n standard uses such an approach for unicast frames. We present the design of a system that can aggregate both unicast and broadcast frames. Further, the system can classify TCP ACK segments so that they can be aggregated with TCP data flowing in the opposite direction. A novel aspect of our work is that we implement and validate our design not through simulation, but rather using our wireless node prototype, Hydra, which supports a high performance PHY based on 802.11n. Our validation shows significant improvements in throughput for each kind of aggregation we support.