A Look-Up Table Based Fractional Order Composite Controller Synthesis Method for the PMSM Speed Servo System

Considering the performance requirements in actual applications, a look-up table based fractional order composite control scheme for the permanent magnet synchronous motor speed servo system is proposed. Firstly, an extended state observer based compensation scheme was adopted to suppress the motor parametric uncertainties and convert the speed servo plant into a double-integrator model. Then, a fractional order proportional-derivative (PDμ) controller was adopted as the speed controller to provide the optimal step response performance for the servo system. A universal look-up table was established to estimate the derivative order of the PDμ controller, according to the optimal samples collected by an improved differential evolution algorithm. With the look-up table, the optimal PDμ controller can be tuned analytically. Simulation and experimental results show that the servo system using the composite control scheme can achieve optimal tracking performance and has robustness to the motor parametric uncertainties and disturbance torques.

A Composite Robust Fault-Tolerant Control Scheme for Limited-Thrust Spacecraft Rendezvous in Near-Circular Orbits

External perturbations and actuator faults are two practical and significant issues that deserve designers' considerations when synthesizing the controllers for spacecraft rendezvous. A composite robust fault-tolerant control (FTC) scheme that does not require the fault information is proposed in this paper for limited-thrust rendezvous in near-circular orbits. Within the control scheme, a reliable integral sliding mode (ISM) auxiliary controller and a modified guaranteed cost FTC are, respectively, developed to attenuate the external disturbances and to stabilize the nominal rendezvous system with actuator faults. Comparisons with previous works as well as a more practical and challenging simulation example are presented to verify the advantages of this composite control scheme.

Research on the Composite Control Scheme for the Stabilized Loop of Inertial Stabilized Platform

A composite control scheme is proposed to solve the problems of friction toque and carrier disturbance lag in the stabilized loop of inertial stabilized platform. Based on analysis of composite control structure, the performance of single rate loop, double rate loop and composite control in the inhibition of carrier disturbance, friction torque and sensor noise are compared. In order to further verify the composite control method, an experimental setup is built. The experimental results show that: when the disturbance is 1deg-1Hz sinusoidal signal, the peak value of residual error of the single rate loop is 0.055 deg, the double rate loop is 0.031deg, and the composite control is the 0.0188deg, so the performance of isolation carrier disturbance of platform is effectively improved.

Trajectory Tracking for Two-Link Flexible Arm via Two-Time Scale and Boundary Control Methods

Main purpose of the study presented in this paper is to demonstrate the boundary controllers design by singular perturbation approach for trajectory tracking of two-link flexible arm. Applying the two-time scale control theory on the nonlinear PDE model, a control scheme is elaborated which makes hubs’ angles track a desired trajectory while damping out the links vibration. In the proposed controller, fast (flexible) subsystem controller will damp out the vibration of the flexible links by a Lyapunov-type design and the other slow (rigid) subsystem Inverse Dynamic controller dominates the trajectory tracking. These two controllers constitute the composite control scheme. The method does not require any information about the vibration of the links along the links for the proposed fast control law as well as discretizing the PDE of arm vibration to set of ODEs. Therefore, the method excludes the effect of both observation and control spillover instability. The simulation results confirm that the proposed boundary controllers are quite effective in performance.