. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 10 y, cm V (Forward speed) -y. (Descent angle). Figure 1. (a. b) Three-dimensional reconstruction of two typical landing trajectories, from video films. Vertical lines depict height above surface, (c) Illustration of some of the variables analyzed to investigate the control of landing, h (cm): height above surface; Vf(cm/s): horizontal (forward) flight speed; Vj (cm/s): vertical (descent) speed; Tan~'(Vd/Vf) (deg or radl: descent angle. Adapted from Srinivasan el al. (2000). al. (2000), who video-filmed trajectories, in thre
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 10 y, cm V (Forward speed) -y. (Descent angle). Figure 1. (a. b) Three-dimensional reconstruction of two typical landing trajectories, from video films. Vertical lines depict height above surface, (c) Illustration of some of the variables analyzed to investigate the control of landing, h (cm): height above surface; Vf(cm/s): horizontal (forward) flight speed; Vj (cm/s): vertical (descent) speed; Tan~'(Vd/Vf) (deg or radl: descent angle. Adapted from Srinivasan el al. (2000). al. (2000), who video-filmed trajectories, in three dimen- sions, of bees landing on a flat, horizontal surface. Two examples of landing trajectories, reconstructed from the data, are shown in Figure la, b. A number of such landing trajectories were analyzed to examine the variation of the instantaneous height above the surface (h). instanta- neous horizontal (forward) flight speed (Vf), instantaneous descent speed (Vt/) and descent angle (a). These variables are illustrated in Figure Ic. Analysis of the landing trajectories revealed that the descent angles were indeed quite shallow. The average value measured in 26 trajectories was about 28° (Srinivasan et al., 2000). Figure 2a, b shows the variation of flight speed with height above the surface, analyzed for two landing trajec- tories. These data reveal one of the most striking and consistent observations with regard to landing bees: Hori- zontal speed is roughly proportional to height, as indicated by the linear regression on the data. When a bee flies at a horizontal speed of Vf cm/s at a height of /; cm. the angular velocity w of the image of the surface directly beneath the eye is given by u> = Vflh rad/s. From this relationship it is clear that, if the bee's horizontal flight speed is proportional to her height above the surface (as shown by the data), then the angular velocity of the image of the surface, as seen by the eye, must be constant as the bee approaches i
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
