Set a plane x-y coordinate system (coincident with absolute acceleration as far as possible), and project (1) to two coordinate axes-> respectively; Two algebraic equations are obtained. The absolute acceleration is on the left of the equal sign, and the projection is positive in the same direction as the coordinate, otherwise it is negative; Each component is projected on the right of the equal sign of this coordinate, and the projection direction is positive if it is the same as the absolute acceleration projection direction, otherwise it is negative.

(Projection of vector equation on X axis: 0=ar.cosφ-ae.cosφ-ac.sinφ, (2)

The vector equation is projected on the y axis: aa=-ar.sinφ+ae.sinφ-ac.cosφ, (3)

* As shown in Formula (2), when the absolute acceleration projection is zero, the component projection is positive when the coordinates are in the same direction, otherwise it is negative: if the unknown acceleration is negative, the actual direction of the acceleration is opposite to the set.