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CONTEMPORARY ROBOTICS - Challenges and Solutions Part 7

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Tham khảo tài liệu 'contemporary robotics - challenges and solutions part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Generic Real-Time Motion Controller for Differential Mobile Robots 171 -rr rad referred to the motor. Referring to the wheel this results in rad. By this the g 2048X3.71 y robot wheel velocity vector in rpm rotations per minute is E . . .60. 2048X3.71 25 _ .1_ pulse-Count where v-1 v- - samp-1000 2re 3.1.6 Displacement Reader Due to the fact that the implemented Kalman filter needs a specific input vector of Ad and Ah linear and angular displacements respectively it is necessary to determine such values for every control loop as . _ di d-2 di d2 26 Ad - - ầh ------ 2 b wherein b is the distance between wheels and dv d2 the distance walked by the left and right wheels respectively. This is done simply using odometry data and counting pulses between sample instants to determine d1 and d2. Then knowing how many pulses it takes for a complete revolution of the wheel i.e. 2TW we can easily determine the linear displacement of each wheel. 3.1.7 Kalman Filter for Sensory Fusion A differential robot possessing an odometer system is equipped with an encoder in each motor. An angular displacement of a radians on the rotor corresponds to a moved distance d on the periphery of the wheel and subsequently to an encoder count. The distance is given by d ka with k - being r the radius of the robot. If the robot s movement is assumed to be linear the distances d1 and d2 walked by the left and right wheels respectively can be transformed into linear and angular displacements through 26 . For a particular sample instant k the following is given . _ d-Lk d2k dlk d2k 27 K 2 K b The robot s coordinates referenced on the world s coordinate frame can be determined by these simple relations . . Ah 28 fc i xk AdfcCos hk -y Yk 1 Yk àdk sin hfc hk 1 hk Ml These coordinates constitute the state vector and are observed by the vision s coordinate state vector z. Note to the reader It is important at this time to refer that we use a global vision system capable of detecting the .