In order to overcome the limitation of the force sensor to measure the actual contact force, when the end point of contact force is far from the force center, the relationship between the actual force and the measure force is analyzed and derived, force information or torque information is used respectively to estimate the force control and position control direction, and the estimated vectors are used to generate the virtual reference trajectory. The reference scaling factor is
developed to tune the reference trajectory, and the reference scaling factor is determined by fuzzy reasoning in accordance to the information feedback on forces in contact. Experimental result shows its force tracking capability.