Research On Trajectory Planning And Nonlinear Sliding Mode Control Of Bridge Cranes With Distributed Mass Payload

As an engineering machinery supporting the construction of the national economy,cranes with its remarkable advantages such as simple structure,low energy consumption,high flexibility,strong holding payload,are widely used in ports,workshops and warehouses,marine exploration,aerospace,environmental protection industry,wind power and nuclear power and many other fields.As a typical underactuated system,the variation of system velocity and the influence of external disturbances(such as wind)will result in the oscillations of the payload,which will seriously affect the working efficiency and operation safety of the crane.Aiming at the control problem of crane system,researchers have carried out a lot of work and achieved fruitful research results.However,the existing control methods focus on the single pendulum crane system with point mass payload.In practical application,payloads with a large ratio of length and width,such as profiles,fan blades and aircraft wings,are typically attached by two or four rigging cables.Compared with the single pendulum crane with point mass payload,specific payload shape and hoisting mechanism will induce to complex double pendulum dynamics,which brings great challenges to the control research of the crane system.Considering the above problems,this paper carries out insightful research on the rapid transportation,oscillation suppression,state measurement and application of double pendulum bridge crane with distributed mass payload:(1)Dynamic modeling and oscillation mechanism analysis of bridge crane with distributed mass payload.Based on the Lagrangian equation,a nonlinear dynamic model of the double pendulum system of a bridge crane with distributed mass payload is established,and then the complex oscillation mechanism of the double pendulum system with distributed mass payload is revealed.Based on the theory of two degree of freedom undamped free oscillation,the oscillation law of the hook and payload is studied.Based on the above analysis,the oscillation of the distributed mass payload is divided into a quasi-simple pendulum around the drum and a double pendulum around the hook,and a quasi-simple pendulum model is established.(2)Trajectory planning control method for bridge crane with distributed mass payload.Based on the dynamic analysis of double pendulum bridge crane,the time optimal control method of quasi single pendulum model is proposed by utilizing the minimum principle and phase plane method.Based on the rectangular impulse response law of oscillation system,the oscillation suppression strategy of the double pendulum is designed.Combined with the above two methods,the time optimal trajectory planning control method is proposed to realize the rapid transportation and oscillation suppression of the payload.Furthermore,according to the high-frequency suppression characteristics of low-pass filter,combined with the above proposed methods,an improved time optimal trajectory planning control method is proposed to achieve the minimum payload residual oscillation angle.A large number of simulations and experiments are conducted to verify the effectiveness of the two proposed trajectory planning control methods.(3)Nonlinear sliding mode controls of double pendulum bridge crane considering distributed mass payload,varying roped length and external disturbances.Based on the hierarchical linear sliding mode control method,the system response characteristics of two different control methods of velocity and displacement are analyzed,and the velocity is determined as the control method of the proposed method.Meanwhile,considering the frequency of payload oscillation,a payload state observer with adaptive rope length variation is proposed.Based on the above methods,two hierarchical nonlinear sliding mode control methods considering velocity control,rope length variation and external disturbances are established.Simulation and experimental results demonstrate that the proposed control method can effectively suppress the payload oscillation,maintain robustness in disturbances and does not need the payload state measurement,so it is easy for industrial application.(4)Vision measurement of multi-information of the bridge crane’s workspace.By analyzing the imaging model of monocular camera and using the spatial characteristics of bridge crane,the hierarchical calibration strategy is proposed.By using the numerical analysis method,the mathematical models of payload hoisting height and payload hoisting center are established.On this basis,combined with the geometric relationship of the bridge crane workspace,the measurement models of payload angle(including the payload angles of the single and double pendulum),off-centered distance,rotation angle and obstacle height are established,respectively,and the multi-information real-time measurement system of the bridge crane workspace based on machine vision is developed.Finally,the experiment verifies the validity of the designed measurement model.In addition,the measurement method is successfully applied to the auto-centering control and automatic obstacle avoidance of the prototype of bridge crane.(5)Control system design and field test.Considering the practical application requirements,this paper designs an electrical system composed of programmable logic controller(PLC),frequency inverters,hoisting rope length measurement sensor and human machine interface for the 16 ton industrial bridge crane in profile warehouse,and the industrial application test of the time optimal trajectory planning control method proposed in this paper is realized.Field test results show the effectiveness of the proposed trajectory planning control method.In addition,for the shortcomings of PLC in control algorithm implementation,response speed and control accuracy,etc.this paper develops an embedded special control module for bridge crane based on STM32F4 microprocessor controller.