| Tunnel boring machine(TBM)is a large-scale construction equipment with the function of excavation,dust removal,profile support and track laying.With the advantages of efficiency and safety,it has been used in the long-distance and big-section hard rock tunnels worldwide.The driving system of TBM mainly consists of the over-actuated cutterhead driving system(CDS)supplying the torque,and the attitude adjusting system with parallel cylinders to thrust and change the orientation.The dynamic and kinematic responses of these highly integrated subsystems in complex situations couldn't be described and controlled accurately by mathematic approach alone;in-situ research is also limited by abominable field conditions.Currently,these driving subsystems are designed and controlled empirically,which results in that TBM may easily sheer in mixed stratum,the redundant electro-motors are always unevenly loaded and the cutterhead may easily get stuck due to the poor driving capacity of electro-motors.In this paper,these driving subsystems are modified based on the load feature and topology analysis,then coordinated control strategies are proposed based on the kinematic and dynamic characteristics,and are verified by simulation and experiment.This research has important theoretical value and practical significance to improve the excavation performance and geologic adaptability of TBM.The major contents are summarized as follows:In chapter 1,the operating principle of TBM and its general development in domestic and overseas are introduced.Current research of TBM in the fields of load feature and topology,rectification trajectory planning and kinematic control,gear dynamics and torque synchronization of CDS,cutterhead off-stuck are analyzed,respectively.In the end,the main contents,significance and difficulty of this thesis are presented.In chapter 2,novel design and operation principles of the driving system are summarized based on the load feature and topology analysis.New load model of the cutter group is built based on classical CSM(Colorado School of Mines)model with exact influence factors of cutterhead diameter,cutter space,cutter geometry,rock properties and penetration ratio(PR).Subsequently,the guidance for cutter group design and maintaining in different situations are summarized,and some monitoring indices independent with PR,such as FPI(1)(unit force PR index)?SE(1)(unit special energy)?TFP(unit torque/force PR index),are also proposed.Combining with the coefficients of TBM diameter to the unnormal load caused by rock convergence and accumulation,design principles for the driving types of CDS and thrust structure are developed.Based on topology analysis,parallel cylinders are decoupled to be fully-actuated,and the conditions to change back to traditional under-actuated system with higher compliance are also discussed based on the transfer of unbalanced thrust load.Finally,the newly designed driving system is established on the 02.5m test rig to support following research.In chapter 3,the automatic attitude correction of TBM is realized by rectification trajectory planning,reverse kinematics and coordinated control of parallel cylinders.A trajectory planning method with adaptive orientation and curvature is proposed against different target tunnel axes and attitude errors,and the adjusting weights between position and angle errors are optimized by fuzzy logic,so errors within +2mm along axial direction and +0.3mm along perpendicular directions could be overcome.Based on tropology analysis,reverse kinematics for parallel cylinders in vertical and horizontal directions are separately carried out according to the radius and excavation rate of planned trajectory.For the quick response and accurate tracking of large inertia equipment,a compound controller is designed,including speed-flow feed-forward with dead-band compensation and displacement feedback by fuzzy proportional-integral(PI)control with separated integration.At highest excavation rate and minimum radius,the tracking errors of high-speed thrust cylinders and low-speed torque or gripper cylinders,which are separately within±0.8mm and±0.13mm,could meet the tolerance of trajectory planning.The synchronous errors of thrust and torque cylinders are with ±0.4mm and ±0.1mm,respectively.Thus the attitude correction of TBM could be finally realized by the displacement control in joint space.In chapter 4,the torque synchronization and stability control for the over-actuated CDS are studied based on the dynamics of multi-stages parallel gear transmission system and vector control of electro-motors.With the force transfer between lumped elements with relative motions,the electromechanical coupled model is established considering time-varying meshing stiffness,nonlinear backlash,parallel gear phases,bearings vibration and the interaction between different stages.Through mathematic and simulation approaches,the mesh phasing theory is verified to use odd teeth in gear train with equally spaced four planets.Then the frequency and phase features of vibration and meshing responses at the harmonics of meshing and carrier rotation frequencies are analyzed.The interaction between multi-stages of reducer is suppressed by the serial and inverted meshing pairs of equally spaced planets,but the meshing feature between unbalanced pinions and central gear would be motivated.Comparative study on the stability and torque synchronization performances under different multi-motors control strategies are carried out by simulation and experiment against inconsistent parameters and uneven disturbances.With lower rigidity in the speed controller of torque master-salve strategy,the vibration of synchronous torque could be significantly decreased and is optimal.In chapter 5,the hybrid off-stuck strategies of CDS are proposed with hydro-motor acting as torque follower.A half open-type hybrid system is proposed,in which hydro-motor pressure tracks the main-motor torque by proportional overflow valve(POV)and pump displacement tracks the main-motor speed.A variable pump speed hybrid system is also proposed with the pump driving electro-motor tracking the main-motor torque to indirectly control the work pressure.These two hydraulic systems are built in AMEsim and are co-simulated with previous model in chapter 4 in Simulink.After comparing the shock,efficiency and reliability at different work conditions,the former is established on the test rig.Based on the mechanism analysis of POV with stable pilot flow and variable pump of displacement direct feedback structure,feed-forward principles for pressure and displacement control are separately derived to combine with feedback PI controller of integral separated structure.In normal condition,the torque tracking error ratio of hydro-motor is within±9.2%,which is similar to the slave electro-motor.In off-stuck condition,only 25%of the required power for electro-motor is needed to generate identical torque.In chapter 6,the major research work and results of this thesis are summarized.In addition,suggestions for further research on this subject are presented. |
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