This paper presents a method to estimate external forces exerted on a manipulator, avoiding the use of a sensor. The method is based on task-oriented dynamics model learning and a robust disturbance state observer. The combination of both leads to an efficient torque observer that can be incorporated to any control scheme. The use of a learned based approach avoids the need of analytical models of friction or Coriolis dynamics effects.
Colomé, A. [et al.]. External force estimation during compliant robot manipulation. A: IEEE International Conference on Robotics and Automation. "The proceedings of the 2013 IEEE International Conference on Robotics and Automation". Karlsruhe: 2013, p. 3535-3540.