Power Balance of Starting Process for Pipe Belt Conveyor Based on Master-Slave Control
An output power imbalance usually occurs in the driving motor of pipe belt conveyor due to the load disturbance and a variety of environmental interferences. This paper focuses on the operating condition of pipe belt conveyor where the head and tail with inclined angle are equipped with a motor separately. The discrete element method is used to propose a discrete model of the pipe belt conveyor, and its simulation model is established in the AMESim. According to the direct torque control method for the three-phase asynchronous motor, the principles for controlling the balance of dual-motor power are analyzed. A master-slave control strategy is proposed, where the master motor is controlled using a speed-given strategy and the slave motor is controlled using a torque-given strategy. A simulation model is built for the dual-motor driven system in the MATLAB-Simulink. After establishing a correlation between parameters through VS2010, a joint simulation model was established for the control system of the pipe belt conveyor. Simulation analysis and field test of the starting process are performed. Results of comparison with the traditional master-slave control strategy demonstrate the ability of the proposed method to balance the master-slave motor power of the pipe belt conveyor more effectively.
High-Precision Coordinated Position Control of Integrated Permanent Magnet Synchronous Linear Motor Stations
In multi-station linear reciprocating processing systems, the positioning accuracy and the cooperative precision of the motion stations directly affect the production quality of products. This paper aims to enhance both the positioning and the coordination accuracy of the motion stations from the integrated permanent magnet synchronous linear motor (IPMSLM) stations during the reciprocating motions, especially in the presence of load disturbance. Firstly, the adaptive control strategy based on pole placement principle with online parameter identification is proposed for single IPMSLM station. The least squares identification algorithm with forgetting factor is employed to calculate the mathematic model online, so as to solve the problem that the IPMSLM stations cannot be accurately modeled with the existence of parameter perturbation and load disturbance. Secondly, in order to improve the coordination performance of the IPMSLM stations, the cooperative error equation is proposed, and a ring coupling cooperative (RCC) control strategy based on Lyapunov stability theorem is designed. The accuracy and effectiveness of this proposed collaborative control strategy is verified by experiments under no-load and spring-load conditions. Experimental results show that for the proposed adaptive and coordinate control strategy, the positioning error and the coordination error during the reciprocating motion can be guaranteed uniformly within $\pm 8~\mu \text{m}$ and $\pm 10~\mu \text{m}$ , respectively.
Corporations and the Market for Law
The state competition for corporate law has long been studied as a distinct phenomenon. Under the traditional view, corporations are subject to a unique choice-of-law rule, the internal affairs doctrine (IAD). This rule is explained as a historical accident, or by the special logistics of the corporate contract. The resulting market for corporate law appears to have special characteristics, particularly including the dominance by the single state of Delaware. This paper challenges the traditional view. It shows that the corporate law market is best understood as a special application of the general market for law. Any differences are matters of degree rather than kind, and are explained by considerations underlying enforcement of all choice-of-law contracts rather than by factors unique to corporations. It follows that theories of corporate competition that ignore the broader law market context are incomplete, and that the competition for corporate law carries lessons for the law market generally. Moreover, the connection between the corporate and other law markets has implications for the nature of corporate law, the constitutional status of the IAD, the scope of the IAD, and for the relationship between state and federal law.