This paper has designed a special robot working in a narrow space. Planning an appropriate path is one of the significant problems. In this paper, a mathematical expression of the G  value considering obstacles in the environment based on A* algorithm in low-dimensionality is proposed. The algorithm is a approaching path planning algorithm in static, known environments. We plan the path of the end-effector after it moves near the obstacles. As only the end-effector changes drastically, it is safe for other joints working in the collision environment if the other joints are obtained using inverse kinematics. The simulation result validates the effectiveness of our algorithm.