This paper presents a study on developing a hybrid 3D position observer for a rover with acceleration and relative distance measurements. The observer design utilizes two different methodologies; a Trajectory Based Optimization Design (TBOD) and a Linear Matrix Inequality (LMI) method. We prove that, under the proposed solutions, the boundedness of the estimation error is guaranteed. The performance of the observer is evaluated and compared to a standard EKF using comprehensive Monte Carlo simulations.