# Environment Perception with Chameleon-Inspired Active Vision Based on Shifty Behavior for WMRs
## 2 Visual Perception Modelling in Chameleon-Inspired Shifty-Behavior Mode for WMRs
In the above figure, \(W,R\) denotes the world coordinate system and the robot body coordinate system, both located at the geometric midpoint of the body differential mechanism; \(G_{b}\) denotes the neck coordinate system, located at the center of the PTZ beam; \(G_{l},G_{r}\) denote the left and right PTZ coordinate system, located at the rotation centers of the left and right sides of the PTZ; \(C_{l},C_{r}\) denote the left and right camera coordinate system, located at the optical centers of the left and right cameras; \(X_{l}\), \(X_{r}\) denote the left and right camera imaging coordinate system; and \(I_{l},I_{r}\) denote the left and right camera image coordinate system; \(P_{cl}(x_{cl},y_{cl},z_{cl})\) denotes the coordinates of the target point in the left camera coordinate system; \(P_{xl}(x_{xl},y_{xl})\) denotes the coordinates of the target point under the left camera imaging coordinate system; \(P_{ll}(u,v)\) denotes the coordinates of the target point under the left camera image coordinate system. During the process of environmental perception using their eyes, chameleons adopt a shifty-behavior mode according to the functional requirements at different stages. In the target search stage, the binocular negative-correlation motion mechanism with the wide-angle camera mode is used to perform a rapid wide-range scanning of the environment. In the target tracking stage, once the target is detected, the two eyes are coordinated and synchronized to achieve stereo vision, which precisely measures the depth information of the target and makes the outstretched tongue catch the prey just right, and the focal length is appropriately increased to improve the measurement accuracy. Based on the visual behavioral mechanism of chameleons, a visual perception model in the chameleon-inspired shifty-behavior mode for WMRs was established, as shown in Equation (1). \[\left.\begin{array}{l}P_{v}\left\{ \begin{array}{l}S_{ngg}\left[\left(\phi_{ ngg},\varphi_{ngl},\varphi_{ngr},\theta_{ngl},\theta_{ngr},f_{ng}\right)\rightarrow \left(F_{ngg},C_{ng}\right)\right],\\ B_{co}\left[\left(\phi_{cob},\varphi_{clc},\varphi_{cor},\phi_{cor},\phi_{cor},f_{co}\right)\rightarrow\left(F_{cov},D_{co}\right)\right]\end{array} \right\} \\ \text{s.t. }\left\{ \begin{array}{l}(\phi_{b})_{\min}\leq\phi_{b}\leq(\phi_{ b})_{\max}\\ (\phi_{l})_{\min}\leq\phi_{l}\leq(\phi_{l})_{\max}\\ (\phi_{r})_{\min}\leq\phi_{r}\leq(\phi_{r})_{\max}\\ (\theta_{l})_{\min}\leq\theta_{l}\leq(\theta_{l})_{\max}\\ (\theta_{r})_{\min}\leq\theta_{r}\leq(\theta_{r})_{\max}\\ f_{\min}\leq f\leq f_{\max}\end{array} \right. \tag{1}\]  
where \(P_{v}(\cdot)\) denotes the visual perception model in the chameleon-inspired binocular shifty-behavior mode for WMRs, \(S_{ng}(\cdot)\) denotes the target search model with the chameleon-inspired binocular negative-correlation motion, \(\left(\phi_{ngb},\varphi_{ngl},\varphi_{ngr},\theta_{ngl},\theta_{ngr},f_{ng}\right)\) denotes the action set of the dual PTZ vision system in the target search stage, and \(\left(F_{ngg},C_{ng}\right)\) denotes the output set of the vision system in the target search stage, and the action set determines the output set. \(F_{ngg}\) denotes the field of view (FOV) acquired by the chameleon-inspired binocular negative-correlation motion, \(C_{ng}\) denotes the target features detected by the selective attention algorithm, \(B_{co}(\cdot)\) denotes the target tracking model with the binocular synchronous motion, \(\left(\phi_{cob},\varphi_{col},\varphi_{cor},\theta_{col},\theta_{cor},f_{co}\right)\) denotes the action set of the dual PTZ vision system in the target tracking stage, and \(\left(F_{cov},D_{co}\right)\) denotes the output set of the vision system in the target tracking stage, and the action set determines the output set. \(F_{cov}\) denotes the FOV acquired by the binocular synchronous motion, and \(D_{co}\) denotes the depth information of the target acquired by the binocular stereo vision.