Fast and exact motions of continuum robots are hardly seen so far. Partly this is caused by physical constraints, e.g. small available actuation forces. Another reason is the dynamic coupling between the actuators that cannot be neglected during fast motions. Therefore, a model-based MIMO controller in actuator space was developed, that is based on a spatial dynamic model with one mass point per section. Using feedback linearization, the actuators can be decoupled and feedforward control in combination with linear controllers can be applied. Measurements of an example manipulator show the good tracking result of pure feedforward action with feedback linearization. Adding a linear PD-controller increases the robustness against disturbances without reducing the possibility of fast motions.

In the previous decade, multiple useful approaches for kinematic models of continuum manipulators were successfully developed. However, dynamic modeling approaches needed for fast simulations and the development of model-based controller design are not powerful enough yet-especially for spatial manipulators with multiple sections. Therefore, a practicable lumped mass model similar to common dynamic models of rigid-link manipulators is needed, which can be used for simulations and model-based control design. The model incorporates mechanical interconnections of parallel and serially connected bellows and uses constant curvature kinematics and its analytical derivatives to balance forces and energies in a global reference frame. The parameters of the resulting model are identified with measurements before the simulation results are experimentally validated. The obtained dynamic model can be used to both simulate the manipulator dynamics and calculate the inverse dynamics needed for model-based controller design or path planning.

Dynamic models of continuum manipulators tend to become very complex, especially for spatial manipulators with multiple sections. Therefore a practicable model is needed that can be used for simulations and model-based control design. Neglecting rotational energies and assuming a continuum manipulator that consists of a single concentrated mass per section, dynamic equations for each actuator state are derived using the Euler-Lagrange formalism. Forces, positions and velocities are transformed to a global reference system using the homogeneous transformation based on constant curvature robot kinematics and its derivatives. Measurements of an example manipulator verify the resulting dynamic model that can be used to both simulate the dynamics and calculate the inverted robot dynamics needed for model-based controller design.

We present a new variable curvature continuum kinematics for multisection continuum robots with arbitrarily shaped backbone curves assembled from sections with three degrees of freedom (DoFs) (spatial bending and extension, no torsion). For these robots, the forward kinematics and the differential forward kinematics are derived. The proposed model approach is capable of reproducing both the constant and variable backbone curvature in a closed form. It describes the deformation of a single section with a finite number of serially connected circular arcs. This yields a section model with piecewise constant and, thus, a variable section curvature. Model accuracy and its suitability for kinematic real-time control applications are demonstrated with simulations and experimental data. To solve the redundant inverse kinematics problem, a local resolution of redundancy at the velocity level through the use of the robot's Jacobian matrix is presented. The Jacobian is derived analytically, including a concept for regularization in singular configurations. Experimental data are recorded with Festo's Bionic Handling Assistant. This continuum robot is chosen for experimental validation, as it consists of a variable backbone curvature because of its conically tapering shape.

This paper handles the control of flexible link robot systems. Since in the considered case a manipulator for grabbing containers is suspended on two ropes, torsional oscillation occurs changing the position of the manipulator. A control strategy, which consists of feedforward and disturbance observer based feedback control implemented on boom cranes to assure an accurate tracking of the manipulator along a reference path is shown. The system parameters like rope length, moment of inertia of the load and its mass are changed frequently during the crane operation. Therefore the controller is fully adaptive due to the varying system parameters. Measurement results show the efficiency of the presented control strategy implemented on a harbor mobile crane LIEBHERR LHM 400.

Because of their high power/weight ratio pneumatic actuators, especially the so called pneumatic muscles, are very interesting for the use as actuators in robotics. But, in fact the physical model is highly nonlinear, in the following a flatness based position controller for the pneumatic artificial muscles is presented. The considered pneumatic muscle is produced by the manufacturer Festo and possesses a high pulling force to 4000N and a very long lifetime at least to 10 million switching cycles. The control objective is to track the payload along a specified reference path including an active attenuation. Since a model based control approach is pursued, a physical model is presented for an experimental setup. The model is very nonlinear making nonlinear flatness based control desirable. Experimental results are included and demonstrate the efficiency of the control.