Research On Stabilized Pan-tilt Attitude Control System Based On ARM

With the development of technology and people’s living standards improved, more and more occasions require a stable platform environment, thereby reducing the vibration interference on the related device or instrument. It’s difficult to achieve ideal stable platform under natural conditions, thus, it’s of significant value to develop a high precision and low cost stabilized pan-tilt device. In this paper, aiming at creating an active stabilized platform, an ARM based attitude control system of stabilized pan-tilt device has been studied.In this paper, firstly discussed the structure and stability of a physical model of pan-tilt, then analyzed the principle of active vibration elimination. A Cortex-M3 micro controller has been developed with MEMS motion sensors for pan-tilt attitude detection and permanent magnet synchronous motors for action execution. Magnetic encoding sensors are responsible for rotor position feedback. Pan-tilt attitude solution algorithms and field-oriented motor control algorithm have been studied regarding above hardware platform. In the solution of pan-tilt attitude, studied strap-down inertial navigation system in this paper has the advantage of little calculation and high detection precision by extract the Euler angles from attitude quaternions from a tri-axial accelerometer output and three axis gyroscopes’ outputs. At the same time, this paper also studied how to adopt the ellipse fitting algorithm to guarantee the pan-tilt attitude detection accuracy, by correcting the yaw angle using magnetometers.This paper takes strategy of magnetic field vector orientation control for permanent magnet synchronous motor, to guarantee the rotor position. The application of non-contact magnetic encoder in measuring rotor position has also been studied, to provide a guarantee for realizing the motor position, speed and current closed-loop control. At the same time, in order to simplify circuit design, reduce the board size, and decrease the cost of the pan-tilt, this paper studies the single resistor sampling of three-phase current reconstruction technology.In the overall design process, this paper has adopted a modular design concept. Attitude detection and motor control units were controlled by separate micro controllers, by the IIC communication to coordinate actions between each other. Recommended configuration not only simplifies the difficulty of design but also improves the control precision and stability.Finally, through actual experiments, studied pan-tilt attitude detection model with MEMS sensors in the initial reading and attitude of Euler angles, has successfully implemented the yaw angle correction. Besides, a prototype of the permanent magnet synchronous motor controller has been developed, to verify the feasibility of the system design.