Chifu Yang

Attitude synchronous tracking control of double shaking tables based on hybrid fuzzy logic cross-coupled controller and adaptive inverse controller

The purpose of shaking tables is to replicate the desired motion to specimen, which needs to ensure not only the synchronization precision of two tables, but the tracking precision for the desired signal. Due to the nonlinearity of system and eccentric of load masses, both tracking and synchronous accuracy are poor. To solve this problem, this article proposes a novel hybrid controller combined a hybrid fuzzy PD cross-coupled controller (CCC) with an adaptive inverse controller (AIC). Based on state variable error optimal control idea, a 2-stage parallel hybrid fuzzy logic controller (FLC) composed of fuzzy PD and accelerated fuzzy PD is proposed to CCC to reduce synchronization error. In order to improve the tracking accuracy, an AIC based on recursive extended least square (RELS) algorithm is used to estimate the close-loop inverse transfer functions of double shaking tables to adaptively tune the drive signals. The combination of hybrid fuzzy PD CCC and AIC has the advantage of integrating a superiority of the two control techniques for better control performance. The procedure of the proposed control scheme is programmed, and tests are carried out in various conditions. The test results demonstrated the viability of the proposed hybrid control scheme.

Passive training control for the lower limb rehabilitation robot

It is difficult to obtain an accurate and complete mathematical model for the lower limb rehabilitative robot, and we will do some reasonable approximate treatments when building the model, so the external disturbance, parameter error, unmodeled dynamics and friction are ignored. These reasons will cause poor control performance. The neural network robust control for the lower limb rehabilitation robot based on computed torque method is presented in this paper. The ideal controller according to the Lyapunov stability theories is designed. The ideal dynamic model is controlled by the computed torque method, and RBF neural network controller compensates the unknown uncertainties, then the adaptive robust controller will compensate the approximation error of neural network and the external interference. Therefore the proposed algorithm will improve the system dynamic performance and control accuracy. The controller can guarantee uniformly ultimately bounded. Analysis and the experimental results indict that the proposed algorithm is much more effective and stable than the other control methods when do the passive training.

Dynamic decoupling control strategy for 6-DOF motion simulator based on singular value decomposition

The strong dynamic coupling exists in each channel of 6-DOF motion simulator. Aiming at this problem, singular value decomposition is used to transform coupling physical space to decoupling space of motion simulator. PID controller of decoupling space for each channel of motion simulator is designed, which realizes dynamic decoupling of motion simulator and optimal regulation of control parameter of each channel. The experiment results verify the effectiveness of the proposed dynamic decoupling control strategy.

Space end effector cpaturing hybrid simulation system

The Space End Effector Capturing Hybrid Simulation System is proposed in the paper, the system can be used to simulate the Space End Effector Capturing a Target Spacecraft and test the Space End Effector on the ground. The force and torque of the Space End Effector and the Target Adapter are measured by two 6-DOF force sensors in the system, and the relative motion of the Space End Effector and the Target Adapter can be calculated by the built capturing dynamics model. Then the relative motion is implemented by a hydraulic driven Stewart platform. For the simulation system, the dynamics calculation method is presented to construct dynamics simulation external loop. The stability of the external loop is analyzed to obtain the stability condition. At last, the virtual prototype of Space End Effector Capturing Hybrid Simulation System is built in ADAMS/Simulink. On the basis of these analyses, the whole process of the Space End Effector capturing a Target Spacecraft is simulated successfully.