Development of 6-axis force/moment sensor for a humanoid robot's intelligent foot

In order to walk on uneven terrain safely, the foot should perceive the applied forces Fx, Fy, Fz, moments Mx, My, Mz to itself, and must control itself using the measured values. The applied forces and moments should be measured from the 6-axis force/moment sensor attached to the foot. Each sensor should get the different rated load, because the applied forces and moments to foot in walking are different. Therefore, one of the important things in the sensor is to design each sensor with the different rated load, and the same rated output.In this paper, a 6-axis force/moment sensor (rated load of Fx and Fy are 500 N and Fz sensor is 1000 N, and those of Mx and My are 18 N m, z sensor is 8 N m) for perceiving forces and moments in a humanoid robot's foot was developed by using many parallel plate-beams (PPBs). The structure of the sensor was newly modeled, and the sensing elements (plate-beams) of the sensor were designed by using finite element method (FEM). Then the 6-axis force/moment sensor was fabricated by attaching strain-gages on the sensing elements, finally the characteristic test of the developed sensor was carried out. And the rated outputs from FEM analysis are agreed well with those from the characteristic test.