# Environment Perception with Chameleon-Inspired Active Vision Based on Shifty Behavior for WMRs
## 4 Modelling of FOV in Chameleon-Inspired Active Vision Based on Shifty-Behavior Mode for WMRs
### Simulation Analysis of FOV Model
Figure 7: Relationship between the binocular horizontal merging FOV and parameters in binocular negative-correlation-motion mode: (**a**) relationship surface of \(r_{0}\) with \(a,f;\) (**b**) relationship surface of \(r_{0}\) with \(\alpha,l;\) (**c**) main effect diagram of \(a,f,\alpha,l\) on \(r_{0};\) (**d**) Pareto diagram of \(a,f,\alpha,l\) on \(r_{0}.\)  
Based on the above analysis, in the target search stage, the goal to be achieved by the mobile robot is the rapid perception of a large region of interest, and there is no need to achieve stereo vision for the accurate observation of the target, so the chameleon-inspired binocular negative-correlation-motion mode (with a large binocular merging FOV) and wide-angle camera mode (with a large FOV) are used for environment perception. However, to ensure the continuity of the search area, the rotation angles of the two cameras with the negative-correlation motion should not be too large. In addition, the focal length of the camera should not be too small, otherwise it will affect the initial detection effect of the target. For the functional requirements of the mobile robot in the target tracking stage, on the one hand, to realize stereo vision, the effective binocular FOV (i.e., the binocular overlapping FOV) must be increased; on the other hand, in order to improve the measurement accuracy of the vision system to accurately locate the target, the resolution of the vision system must be improved, so in this stage, the binocular synchronous-motion mode (with a large binocular overlapping FOV) and the long-focus mode of the camera (with a high measurement accuracy) are adopted. However, the focal length of the camera should not be too large, otherwise it will lead to a too-small effective FOV, affecting the detection effect of the target. Figure 8: Relationship between the \(X\) resolution of the vision system and parameters in binocular negative-correlation-motion mode: (**a**) relationship surface of \(\Delta X\) with \(a,f,l\); (**b**) relationship surface of \(\Delta X\) with \(x\), \(z\), \(\Delta w\); (**c**) main effect diagram of \(a,f,l\), \(x\), \(z\), \(\Delta w\) on \(\Delta X\); (**d**) Pareto diagram of \(a,f,l\), \(x\), \(z\), \(\Delta w\) on \(\Delta X\). Environment Perception Strategy in Chameleon-Inspired Active Vision Based on Shifty-Behavior Mode for WMRs  
Chameleons are called \"lions that crawl on the ground\" because their vision systems play an important role in defending and hunting. Chameleons have peculiar eyes, which can move independently without interlocking to achieve panoramic observation, and they can move simultaneously to achieve binocular stereo vision. Inspired by this visual behavior of chameleons, this paper proposes an active-vision environment-perception strategy for WMRs based on a shifty-behavior mode, as shown in Figure 10. This method can reproduce the predation process of chameleons by executing a series of rhythmic movements to achieve the rapid searching, accurate positioning, and tracking of targets, and it can realize the coordinated motion of the robot's body, neck, and eye in that process, i.e., vision-motor coordination [8]. Figure 9: Relationship between the \(Z\) resolution of the vision system and parameters in binocular negative-correlation-motion mode: (**a**) relationship surface of \(\Delta Z\) with \(a,f,l\); (**b**) relationship surface of \(\Delta Z\) with \(x,z\), \(\Delta w\); (**c**) main effect diagram of \(a,f,l,x,z\), \(\Delta w\) on \(\Delta Z\); (**d**) Pareto diagram of \(a,f,l,x,z\), \(\Delta w\) on \(\Delta Z\). (1) Target search stage with chameleon-inspired binocular negative-correlation motion. The functional goal of this stage is to achieve a panoramic perception of the environment; therefore, to speed up the target search and reduce the burden of panoramic information processing, the search mode of the chameleon-inspired binocular negative-correlation motion is combined with the low-resolution mode of short focus.