Self-identification of Cable-driven Exoskeleton Based on Asynchronous Iterative Method

The upper limb rehabilitation exoskeleton with cable-driven parallel structure has the advantages of light weight and large payload, etc. However, due to the non-rigid nature of the actuating cables and the different body shape of the wearer, the geometric parameters of the exoskeleton have a large error. The parameter identification of cable-driven exoskeleton is of great significance. An asynchronous self-identification method for the upper limb 7-DOF (Degree of freedom) cable-driven exoskeleton was proposed and used in a wearable multi-redundant exoskeleton. Asynchronous iteration eliminates the accumulation of joint errors. High identification reliability is achieved by selecting proper identification parameters and optimizing error model.With the method, the geometric parameters of the exoskeleton can be identified by using exoskeleton joint Angle and cable length data. The experiment verifies that the success rate of parameter identification for different wearers is in line with expectations, and the control precision and stability of the prototype are greatly improved after parameter identification.

Transitional Particle Swarm Optimization

A new variation of particle swarm optimization (PSO) termed as transitional PSO (T-PSO) is proposed here. T-PSO attempts to improve PSO via its iteration strategy. Traditionally, PSO adopts either the synchronous or the asynchronous iteration strategy. Both of these iteration strategies have their own strengths and weaknesses. The synchronous strategy has reputation of better exploitation while asynchronous strategy is stronger in exploration. The particles of T-PSO start with asynchronous update to encourage more exploration at the start of the search. If no better solution is found for a number of iteration, the iteration strategy is changed to synchronous update to allow fine tuning by the particles. The results show that T-PSO is ranked better than the traditional PSOs.

A Power Flow Method for VSC-Multi-Terminal Hybrid System Based on Asynchronous Iteration Algorithm

With the continuous development of HVDC technology, the increase in the number of ports in the MTDC system and the increasing complexity of network topology, the deficiency of traditional flow calculation method is becoming clear. In this paper, a power flow calculation method that contains distribution of VSC-MTDC mixed system which based on asynchronous iterative method is put forward. On the basis of the current model converter, by dividing the hybrid system and coordinating calculation of boundary variables, this method achieves the global convergence of the whole system. The shortcomings that numerous converter stations in VSC-MTDC power flow method, slow operations and poor convergence in communication network with large number of nodes, are overcome in this method. Moreover, more control modes in the operation of the converter station are considered. Finally, through the example, the correctness and effectiveness of this method are verified.