MUAVs coordinated standoff target tracking by improved RPG method

The guidance law of multiple unmanned aerial vehicles (MUAVs) for coordinated standoff target tracking consists of two parts, the lateral guidance law which is used for keeping distance with target and longitudinal guidance law which is used for keeping relative phase angle among MUAVs. Reference point guidance (RPG) method could be used for standoff target tracking, but there are some imperfections by this method, e.g., the included angle between UAV's reference line and relative velocity should be acute angle, the turning rate is too small when UAV flies away from target. The improved RPG method is proposed based on the imperfections of the RPG method. The lateral and longitudinal guidance laws of MUAVs for coordinated standoff target tracking are designed, the stability and convergence are analyzed, and the feasibility of this method is demonstrated. Some situations of UAV encircling static target and encircling moving target are simulated separately by the improved RPG method and the original RPG method. By the improved RPG method, UAV could fly to the desired path as fast as it can when it is at arbitrary initial position and in flight direction, and the improved RPG method has higher efficiency than the original RPG method when UAV flies clockwise or counter-clockwise encircling target.