Research On Image Scanning Control System With Non-equlibrium Load

The reconnaissance instrument on the altitude-flight platform has strong viability and high security. Compared with secondary planet, the reconnaissance instrument with same focus could gain much higher resolution image, and it is also much more flexible. The image scanning system of one high altitude visible-light camera was chosen to be researching object, and the assembly method, the non-equilibrium load feature and relative control methods are discussed in detail.The actuality of the domestic or overseas high altitude aerocraft and reconnaissance camera was given first, and also the strongpoint and shortcoming of the mechanical assembly and optical assembly were pointed out. Then one dynamic scanning assembly actuated by cam was introduced. Some factors, such as the special structure of the cam, platform attitudes angles and camera azimuth cause the non-equilibrium feature of the system load torque, and it was analyzed in theory. In order to predigest depiction, the sums of platform roll angle and camera azimuth is marked to be angleε. The analysis result shows that load torque on the electromotor axis is directly proportional toεand cam speed. Whenεis zero, the load torque equals zero in the uniform section of the follower and it changes in the speed section of the follower. But whenεis not zero, the situation is different. The load torque doesn’t equal zero in the whole circle rotating track of the cam. The academic analysis of the load torque feature provides foundation for choosing control method.Whenεis zero, the methods, PD control, traditional lead and log correction, lead and log multi-model control and neural network multi-model control were used to ensure cam rotation speed transiting smoothly in the speed section of the follower. Some experiments were made to verify the methods stated above. Experimental result shows that the methods, PD control, lead and log multi-model control and neural network multi-model control could restrain the cam rotate fluctuating caused by the load torque in the speed section of the follower. At the same time, in the uniform section of the follower, the rotate speed precision of the cam is less than 0.5 %( r.m.s.).Whenεisn’t zero, the load torque has different feature in the lift section and return section of the cam. Those different features cause that the cam rotate speed isn’t same in the lift section and return section. In order to solve this problem, three control methods were induced, which are current-speed double loop control, changing the DC gain of the adjuster or the input signal in the cam lift section or return section. Considering the project realization, the third method was used in the project at last. The experimental result shows that whenεisn’t zero, the rotate speed precision of the cam is less than 0.7 %( r.m.s.) in the uniform section of the follower.Whetherεis or isn’t zero, the control system performance could satisfy the whole system. The imaging experiment was made to the camera and the gained image exposure evenly and has distinct gradations. At the same time, the image is clear and has no image motion. The image scanning system complies with expectative requirement.