There are plenty of low-level controllers for the robots to perform manipulation tasks. Most of them require specifying of either reference motion or force as the input. However, motion or force planning to interact with unstructured environment is very difficult. This letter proposes the use of wave variables which facilitate the computation of suitable reference motion or force through the wave planner framework. The notion is to specify the supplied power, via input wave, instead of desired motion or force. Input wave will be resolved into motion and force according to the port impedance. The method ensures safe manipulation when applying to passive control systems. Experimental results show advantages of using this wave planner with the impedance and force controllers.