This paper proposes a neural approximation based model predictive control approach for tracking control of a nonholonomic wheel-legged robot in complex environments, which features mechanical model uncertainty and unknown disturbances. In order to guarantee the tracking performance of wheel-legged robots in an uncertain environment, effective approaches for reliable tracking control should be investigated with the consideration of the disturbances, including internal-robot friction and external physical interactions in the robot’s dynamical system. In this paper, a radial basis function neural network (RBFNN) approximation based model predictive controller (NMPC) is designed and employed to improve the tracking performance for nonholonomic wheel-legged robots. Some demonstrations using a BIT-NAZA robot are performed to illustrate the performance of the proposed hybrid control strategy. The results indicate that the proposed methodology can achieve promising tracking performance in terms of accuracy and stability.
The cavern characteristics of xanthan gum solution stirred with the impeller of perturbed six-bend-blade turbine (6PBT impeller) were studied based on CFD laminar flow model. The heart-shaped cavern model was presented for predicting the cavern development accurately, and the predicted results were made a contrastive analysis with that of other existing cavern models. Results showed that the calculated values agreed well with the data measured by PIV, which validated the laminar flow model. The correction coefficient k = 0.64 is more suitable to revise the characteristic parameter a in the equation of the heart-shaped cavern model. As a result, the heart-shaped model always keeps high prediction accuracy at the cavern boundary. The cavern boundary curves predicted by the heart-shaped model are in good agreement with the results of CFD simulation, and the cavern development along the axial height can be also realistically exhibited. The heart-shaped cavern model will contribute to increase the prediction accuracy of cavern development. 相似文献