Lai Xuzhi

Control of acrobot based on Lyapunov function

Fuzzy control based on Lyapunov function was employed to control the posture and the energy of an acrobot to make the transition from upswing control to balance control smoothly and stably. First, a control law based on Lyapunov function was used to control the angle and the angular velocity of the second link towards zero when the energy of the acrobot reaches the potential energy at the unstable straight-up equilibrium position in the upswing process. The controller based on Lyapunov function makes the second link straighten nature relatively to the first link. At the same time, a fuzzy controller was designed to regulate the parameters of the upper control law to keep the change of the energy of the acrobot to a minimum, so that the switching from upswing to balance can be properly carried out and the acrobot can enter the balance quickly. The results of simulation show that the switching from upswing to balance can be completed smoothly, and the control effect of the acrobot is improved greatly.

Design of embedded Telerobotics system

To overcome the disadvantages observed in the prevalent telerobotics systems, such as bulky, high power consumption and closed architectures, this paper introduces a novel design of embedded Telerobotics system using the technique integrating embedded Linux and computer network technology, which make the system be more compact and lower power consumption. As an open architecture, the hardware consists of microcontroller, sensor, communication, motion control and power, while the software is developed as a hierarchical structure, including four layers of data acquisition, operating system, device driver and application. Based on this architecture, the robot control center is in charge of object recognition, multi-sensor information fusion, path planning and decision-making. As the result, the whole system has many advantages, such as compact hardware, low power consumption, customization and open architecture. The result of experiment demonstrates the feasibility and stability of the Telerobotics system in the end.

Hybrid control strategy for an underactuated three-link manipulator

This paper presents a hybrid control strategy for an underactuated three-link manipulator with its second joint being passive. The motion space of the manipulator is divided into three stages: order-reduced stage, swing-up stage and balancing stage. Firstly, in the order-reduced stage, a Lyapunov function is constructed for the third joint, and a control law is designed to force the third link to stretch out toward the second one in a natural way. Meanwhile, another control law is designed for the first joint based on the idea of increasing the system energy continuously. Consequently, the manipulator is reduced to a Pendubot-like system. Then, in the swing-up stage, by retaining the designed control law for the third joint, two different control law design methods are proposed for the first joint to force the manipulator to enter into the balancing stage. One method is only based on the system energy, while another one is based on both the energy and the angular velocity of the first joint. Finally, a linear control is employed for the reduced Pendubot-like system, which stabilizes the manipulator at the straight-up unstable equilibrium position. Numerical simulations show that the proposed strategy has the advantages of short settling time and small control torques.

State fuzzy estimation based on online time-delay detection for industrial wireless networked control systems

This paper presents a novel design method for Kalman filter based on fuzzy state estimation with online time-delay detector for industrial wireless networked control systems. Firstly, the description of T-S fuzzy model of industrial wireless networked control systems is given. Secondly, the distribution of network induced time-delay is detected by online detector, and the distribution probabilities of induced time-delay within different distribution are fingered out using probability method. Meanwhile, the T-S fuzzy model takes the distribution probabilities as membership functions. Then, the local filters with respect to all distribution are designed by applying method of Kalman filter, and a global agonic filter is developed by employing fuzzy fusing technique to all of local filters. Finally, the simulation on this design is carried out to verify its feasibility.

Process optimization based on multi-objective optimization model for coking plant production

In coking plant production process of an iron and steel enterprise, the target flue temperature, gas collector pressure and coking time are set by human experience. Itpsilas difficult to adjust them timely according to different conditions, so the anticipant integrated production target canpsilat be reached. In order to solve this problem, a basic optimization idea is proposed, which is with the maximum of coke yield and minimum of energy consumption as the optimization objective and with coke quality and technological requirements as the constraint conditions. Firstly, the multiple linear regression and improved BP neural network methods are used to build a multi-objective optimization model with nonlinear inequality constraints for coking plant production process. Then, the linear weighted sum method and GRG combinatorial algorithm are applied to resolve the multi-objective optimization problem, so as to obtain the optimized target values of flue temperature, gas collector pressure and coking time. Actual application results show that the optimized result by method proposed in this paper can better meet the enterprise needs, and the industrial application effect is good.

Solution of Singularity Problem in Motion Control of Acrobots

This paper gives an integrated fuzzy-control solution of singularity problem in the motion control of an acrobot. First, the singularity that arises in motion control based on Lyapunov function is explained. Then, a fuzzy controller is employed to regulate one of parameters of the control law to solve the singularity problem in the motion control occurred in the motion control law. Finally, two additional fuzzy controllers for different situations are designed to regulate another parameter of the control law in order to improve the control performance. Simulation results show the effectiveness of the proposed control strategy.