摘要
Abstract
The environment in open-pit mines is complex and changeable,with obstacles such as falling rocks and water pits interwoven with soft and sloping roads,posing significant safety hazards.It is prone to cause dangerous situations such as vehicle skidding or overturning.This poses a major challenge to the stability control of unmanned driving vehicles.Therefore,the handling of instability situations by unmanned vehicles in open-pit mine environments is crucial guarantee for ensuring the safe operation.Four-wheel independent drive electric mining trucks are the mainstream development direction of unmanned line-controlled vehicles in mining,which can achieve independent torque control of each wheel and provide a foundation situation for implementing complex vehicle control strategies.To solve the stability control problem of unmanned driving vehicles in open-pit mines,a hierarchical control strategy is proposed.The characterization of vehicle stability and corresponding countermeasures are studied.The upper-level controller calculates the theoretical values of yaw rate and center of mass side slip angle during the driving process of unmanned vehicles by establishing a two-degree-of-freedom vehicle model,while monitoring the actual yaw rate and center of mass side slip angle during vehicle operation.Based on the yaw rate error and center of mass side slip angle error,a sliding mode following controller is designed to calculate the additional yaw moment and additional side slip moment.The middle-level controller establishes an additional moment distribution model based on the degree of instability and then calculates the combined additional yaw moment.The lower-level controller rationally allocates the additional combined moment to each wheel based on the optimal allocation algorithm and,in combination with the longitudinal control driving moment,controls the vehicle's driving or braking.Meanwhile,simulation tests are conducted.Through simulation tests under three working conditions:sinusoidal steering wheel rotation,stepwise steering wheel rotation,and autonomous driving,the effectiveness of the hierarchical control strategy is verified.The results show that the stability of unmanned driving vehicles can be effectively improved through stability control.In the simulation test of the tracking condition,the maximum tracking error on the curve is lower by 16.2%,and minor instability during driving can be avoided.关键词
无人驾驶/稳定性控制/滑模控制/最优控制/分层控制Key words
unmanned driving/stability control/sliding mode control/optimalcontrol/hierarchical control分类
矿业与冶金
