A.  Bicchi, Salisbury, J. K., and Brock, D. L., ?Contact Sensing from Force and Torque Measurements?, The Int. J. of Robotics Research, vol. 12, pp. 249-262, 1993. 

A.  Bicchi, Salisbury, J. K., and Brock, D. L., ?Experimental Evaluation of Friction Data with an Articulated Hand and Intrinsic Contact Sensors?, in Experimental Robotics-III, R.  Chatila and Hirzinger, G., Eds. Berlin Heidelberg, Germany: Springer Verlag, 1993.