Figure 6. Setups of the four conducted experiments: a) Left side shows the end-effector of the aerial robot. A mass pulls on a rope fixated on the end-effector, resulting in a force Fd in the direction of xW = xE . The force is applied offsetted by lE,R with respect to the tool-tip. b) Sliding with constant force application on a rigid, tilted surface. The black arrow indicates the direction of the trajectory. The green line represents the desired trajectory pE,d , which pierces the tilted surface (magnification shows the reference trajectory below the table). The yellow and violet lines represent the two reference trajectories, due to the contact forces, generated by two different values of the admittance parameter KE . c) Peg in hole task with the tool-tip into a funnel. Left side illustrates the moment of contact, the right side illustrates the adapted and fully inserted tool-tip. The funnel is tilted by 15◦ but the desired trajectory orientation RE,d assumes a vertical funnel. Due to the contact forces (indicated by the red arrows) the admittance filter reconfigures the reference orientation RE,r and allows for the pegging. d) Sliding with multiple contacts: The end-effector slides along the surface from the initial contact point (numbered with 1) to the final point (indicated with 3) along the red line. The numbers correspond to the numbers in Figure 13 and indicate where the phases change. 1 indicates a single contact, 2 indicates two contacts, 3 indicates three contacts, with no lateral motion possible and 4 indicates free-flight.
...read more