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We report on the methodology of developing a hybrid model and utilizing it as a template to initiate running behavior in a legged robot. The hybrid model is comprised of a physics-based, rolling, spring-loaded, inverted pendulum (R-SLIP) model, and a data-driven model that compensates for unmodeled dynamics using Gaussian process (GP) regression. The hybrid R-SLIP-GP model retains the R-SLIP's intrinsic running dynamics, as well as improves the template's accuracy without intensive data training and iteration efforts. The proposed hybrid model was evaluated via simulation and in empirical robot running experiments. The results confirm that the added GP-based model greatly improved the model's accuracy, especially discrepancies resulting from the originally difficult-to-model complex leg-ground interactions. In addition, the R-SLIP-GP model was utilized as a complete motion template to design and control the robot's running motion. The experimental results demonstrate that the hybrid template can initiate more stable and power-efficient running motion in the robot than using the R-SLIP template. [ABSTRACT FROM AUTHOR]

Robot manipulators enable large-scale factory automation of simple and repeated tasks. Each manipulation is the result of the robot design and the command inputs provided by the operator. In this study, we focus on the accuracy improvement of practical robot manipulation under uncertainty, resulting in path-specific error values. Existing techniques for reducing the errors use high-precision sensors and measurements to obtain the values of a manipulator to provide feedback control. Instead of compensating errors in operation, this study designs a calibration table to obtain the error value for a designated path. This error is then used to adjust important parameters in the kinematic closed chain models of a manipulators via optimization. The proposed method reduces the cost and the dependence on the calibration process. Experimental results show that the overall accuracy of the manipulator is improved. The proposed method can also be extended to develop the optimal robotic manipulation planning and reliability assessment in the future. [ABSTRACT FROM AUTHOR]

Abstract: We designed and implemented a novel omnidirectional spherical robot. Instead of using wheels or flywheels, a driven ball is installed inside the spherical shell and driven by two orthogonally-mounted rollers; thus, the omnidirectional mobility of the robot with no singularity can be achieved by simple forward kinematic mapping. The dynamic model of the robot is derived, and effect of the model's parameters is evaluated in simulation and discussed. The simulation results also serve as the design guideline for building the empirical system. Several design issues are addressed to ensure the robot's proper development. Finally, the spherical robot is built, and its performance is quantitatively and experimentally evaluated, thus proving its omnidirectional and trajectory-controllable mobility. [Copyright &y& Elsevier]