These results suggest that power mobility training within the first year of life may be appropriate for certain populations at risk of immobility.

Slip between the ground and wheel often cannot be avoided in most applications of mobile robots. However, a majority of controllers developed so far make a no-slip assumption with non-holonomic constraints. To achieve desired performance in the presence of slip, controllers that are robust to slip are required. In this paper, we discuss robust trajectory-tracking control for a differentially driven two-wheeled mobile robot. The structure of a differential flatness controller, which has shown distinctive advantages providing an integrated framework for planning and control, is extended to account for slip disturbances. It is shown that the differential flatness framework can be extended to develop a robust controller based on a dynamic as well as a kinematic model with slip. Simulation results for both kinematic and dynamic controllers are presented to demonstrate the effectiveness of the robust controllers. Experiments with the kinematic controller which is suited to typical laboratory and field mobile robots were conducted to validate the proposed robust controller. The simulation and experimental results show that the proposed robust controllers are effective in the presence of slip.

In this paper we present a study of the dynamics and control of a helicopter carrying a payload through a cable-suspended robot. The helicopter can perform gross motion, while the cable suspended robot underneath the helicopter can modulate a platform in position and orientation. Due to the underactuated nature of the helicopter, the operation of this dual system consisting of the helicopter and the cable robot is challenging. We propose here a two time scale control method, which makes it possible to control the helicopter and the cable robot independently. In addition, this method provides an effective estimation on the bound of the motion of the helicopter. Therefore, even in the case where the helicopter motion is unknown, the cable robot can be stabilized by implementing a robust controller. Simulation results of the dual system show that the proposed control approach is effective for such a helicopter-robot system.

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