A new model has been proposed by PIAP for defining the Forward Kinematics of the flexible modules of our STIFF-FLOP robot arm. The model enables the estimation of the positions of the flexible modules, using as inputs: the pressures in the chambers and the external forces exerted onto the STIFF-FLOP arm. This new Forward Kinematics have been adjusted to be exploited to compute the generic Inverse Kinematics framework that deduces the appropriate system configuration needed for reaching a targeted tip position and orientation in space.
Since this approach is generic and since the arm’s Jacobian is estimated numerically, features can be added as long as a Forward Kinematics method is employed that links the input values (like pressures in chamber) to the desired output values (like module tip pose).
Now, given a desired STIFF-FLOP tip pose in space, the Inverse Kinematics is able to deduce in real-time the appropriate module chamber pressures, to achieve the appropriate overall arm pose. This computation is done taking into account the Single Point Insertion Constraint, to make sure the rigid shaft in between the external arm and our flexible STIFF-FLOP arm enters the body through the spatially-fixed point dictated by the location of the trocar port.
Note that the new tip control is in 6D: indeed, the Inverse Kinematics is now able to handle and generate rotations along the reference tip z-axis, through the combined control of the external arm and the STIFF-FLOP arm.