  In this paper, we propose an algorithm that estimates contact point and force
simultaneously. We consider a collaborative robot equipped with proprioceptive
sensors, in particular, joint torque sensors (JTSs) and a base force/torque
(F/T) sensor. The proposed method has the following advantages. First, fast
computation is achieved by proper preprocessing of robot meshes. Second,
multi-contact can be identified with the aid of the base F/T sensor, while this
is challenging when the robot is equipped with only JTSs. The proposed method
is a modification of the standard particle filter to cope with mesh
preprocessing and with available sensor data. In simulation validation, for a 7
degree-of-freedom robot, the algorithm runs at 2200Hz with 99.96% success rate
for the single-contact case. In terms of the run-time, the proposed method was
>=3.5X faster compared to the existing methods. Dual and triple contacts are
also reported in the manuscript.
