This paper presents a hybrid force position control strategy for position-controlled robotic manipulator. On-line force feedback data are employed to estimate the local shape of constraint. The estimated vectors are used to generate the virtual reference trajectory for the target impedance model, which is driven by the force error to produce a command position to the manipulator. By following the commanded position trajectory the robotic manipulator can follow unknown constraint surface while keeping an acceptable force error in a manner depicted by the target impedance model. Computer simulation is conducted to verify its force tracking capability.