Optimal design of variable assist characteristics of electronically controlled hydraulic power steering system based on simulated annealing particle swarm optimisation algorithm

In order to ensure that bus drivers have superior manipulation and good road feeling at different speeds, variable assist characteristics of electronically controlled hydraulic power steering system (ECHPS) were optimally designed based on simulated annealing particle swarm optimisation (SA-PSO) algorithm. First of all, characteristic points of assist characteristics curves were deduced via bus drivers' preferred steering torque and steering resistance moment at different speeds. Then the optimisation model of rotary valve parameters was built, with the minimum root of quadratic sum of the difference between hydraulic pressure at typical speeds and characteristic hydraulic pressure defined as objective function. The optimisation problem was solved by SA-PSO algorithm. To verify the design method, low-speed lemniscate and high-speed in-between steering simulations and experiments were carried out. The results showed that the low-speed steering portability and high-speed steering road feeling of optimised steering system were significantly enhanced.