Tham khảo tài liệu 'mobile robots current trends part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Mobile Platform with Leg-Wheel Mechanism for Practical Use 139 Fig. 12. Calculation model. a For the trajectory of a leg tip when raising and lowering a wheel. b For Vw and Vw4. c For swing phase. d For wheel mode. Vpp t Vppx t Vppy t Pw2x t AA Pw2x t 0 5 -1 Pw2y t 1 Pw2y t At A9o t tan 1 tan 1 -. 6 oy Pw2x t Pw2x t At w A90 t is the sum of the changes in the projected front steering angle 9ieg t and the body yaw angle 9b t A9o t A9ieg t A9b t . 7 From these variables the angular velocity of the projected front steering shaft 9ieg t and the angular velocity of the front steering 9sf t are determined by calculating ÕB t and using the relationship between 9ieg t and 9 sf t which is determined topologically from the relations below. 9sf t 9leg t 9sf t cos 9Pb t 9rf t sin 9PB t 8 9leg t frf t sin 9Pb t 9 Pb t 9sf t sin 9Pb t 9rf t cos 9Pb t cos fpB t 9 where 9pB is obtained from attitude sensor information on the platform and the pitch adjustment angle. 140 Mobile Robots - Current Trends The angular velocity of the body rotation Sb is Sb t VPQx ạtBơ VPpx t 10 Bự where B is the length of the projection body and VpQx is the x element of the velocity of Pq Fig. 12 b . B t is the length between 0Pp and 0Pq where 0Pp and 0Pq are the positions of Pp and Pq in the body-centered coordinate system. The velocity of Pq VpQ is given by VpQ t 0Pq t - 0Pq t - At - AOo At 11 where AOo is the movement of the origin of the body-centered coordinate system relative to the absolute coordinate system AOo OPW1 t - 0Pwi t - At . 12 The angular velocity of the front steering shaft d sf which is one of the three control parameters is determined by eqs. 6 7 9 and 10 . How to derive velocities of rear-left and rear-right wheel Here we derive the velocities of the rear-left and rear-right wheels Vw3 t and Vw4 t . The velocity generated at point Pp when stopping the right-back wheel Vw4 0 and moving left-back wheel at Vw3 is VpPw3 shown in Fig. 12 b . If we define VpPw4 similarly then the .