This paper presents the solution to inverse kinematics of a mobile manipulator operating in both obstacle free environment and cluttered workspace. This work conceives an optimization problem using bidirectional particle swarm optimization method to obtain the inverse kinematics solution of the mobile manipulator. The bidirectional search algorithm helps to search for the solution faster than conventional unidirectional search. The novel manipulator decoupling technique proposed in this paper enables the system to carry out bidirectional search to find inverse kinematics. Collision detection and obstacle avoidance tasks are undertaken using the algorithm proposed in this work to avoid line type obstacles. A multi-objective optimization problem is formulated with minimum total joint movement as another objective function and collision avoidance as constraint. Numerical are experiments performed on a four degree of freedom manipulator mounted over a mobile base to illustrate the efficacy of the proposed method.