| In fully mechanized coal mining face,the intelligent sensing technology of the powered support plays a key role in ensuring the safety control of the roof and cutting face,the coordinate operation of the three fully mechanized mining machines and the circulating advancement of the mining face.In the process of fully mechanized mining,it is inevitable to produce floor and roof tilt,roof breakage and periodic mining pressure,which leads to the hydraulic support is difficult to achieve the ideal working state.It greatly affects the pose characteristics of hydraulic support,and thus directly leads to the change of the support load performance under this complex working condition.Meanwhile,high pressure,large flow rate and fast liquid supply environment make the friction action of actuator further affect the load characteristics of the hydraulic support.Therefore,it is necessary to investigate the coupling characteristics and sensing method of pose and load of hydraulic support under complex working conditions considering the influence of pose characteristic,friction characteristic of actuator plunger vice and load characteristic,and establish a comprehensive sensing method that integrates pose and load characteristic under complex working conditions.Taking the coupling characteristic sensing of the pose and load of hydraulic support under complex working conditions as the research goal,aiming at the pose sensing of hydraulic support,friction characteristic sensing of actuator,load performance sensing of hydraulic support,and the pose and load characteristics of the hydraulic support under coupling are discussed.The main work is as follows:A pose sensing model of hydraulic support based on Denavit-Hartenberg(D-H)theory was proposed.The mapping relationship of driving space,joint space,monitoring space and pose space was deduced.Based on D-H theory,the pose model of hydraulic support was established under complex working conditions,and the transformation from driving space to pose space was realized.The support height and the pose angle of each associated part of the support were solved by employing the software of MATLAB,and the boundary trajectory of the canopy was obtained by using Alpha shape theory.The influence of the working length of column and equilibrium jack on the posture characteristics of the hydraulic support was further analyzed,the motion mechanism of the hydraulic support was clarified,and the influence law of the working length of column and equilibrium jack on the posture of hydraulic support was proved.A load characteristic sensing model of hydraulic support coupled with pose characteristic was invented.Based on the spatial load symmetry theory,the two-dimensional spatial load sensing mathematical model of the hydraulic support was established by coupling the posture sensing model.The functionary mechanism of the working length of the column and the equilibrium jack on the load characteristics of the support was deeply discussed,and the friction coefficient between the canopy and immediate roof was analyzed.The influence mechanism of the working resistance of the column and equilibrium jack on the load performance of hydraulic support was obtained,and the load characteristics of the canopy,the pin shaft between the canopy and shiled,the front linkage,rear linkage,and the specific pressure of the base was clarified.Showing that increasing the working resistance of the column and equilibrium jack is conducive to improve the load performance of the support,and the increase of the friction coefficient between the canopy and the immediate roof can also increase the load performance of the canopy to a certain extent.It is pointed out that the working resistance of the column is the key factor affecting the load performance of the hydraulic support.A sensing model for actuator plunger vice friction characteristic of the hydraulic support was invented,which is coupled with pose sensing model and load characteristic sensing model.In order to investigate the influence of internal friction of actuator on the load characteristics of the hydraulic support,the friction characteristics of the actuator of the hydraulic support were analyzed.Considering elastic hydrodynamics theory and rough contact theory,a mathematical model with the posture sensing model and two-dimensional spatial load characteristic sensing model,the friction characteristic sensing model was established based on the friction characteristics of water-based bud-shaped composite sealing ring,and the influence law of different working conditions on water-based bud-shaped composite sealing ring was studied.The influences of working conditions such as the initial compression ratio of elastic element,fluid pressure,rod speed,lubricant viscosity,surface roughness of elastic element,and other factors on the friction mechanism of bud-shaped composite sealing ring of the actuator were quantitatively analyzed.The influence mechanism of different sealing structure and working condition on the plunger viceis friction characteristics of water-based bud-shaped composite sealing ring was revealed.It is illustrated that the increase of rod speed is conducive to increase the fluid dynamic pressure effect and the corresponding friction force decreases,while highpressure fluid,high compression ratio and rough friction pair are not conducive to the decrease of friction.A critical roughness value of water-based bud-shaped composite sealing ring corresponding to stable friction force was obtained.A three-dimensional coupled driving,pose and load characteristics sensing model of hydraulic support was proposed,which coupled the posture characteristic,load characteristic and friction characteristic of actuator plunger vice.Based on the spatial load asymmetry theory,the three-dimensional spatial load coupling driving sensing mathematical model,posture sensing model and load characteristic sensing model of hydraulic support was developed,which couplied the posture sensing model,two-dimensional spatial load characteristic sensing model and friction characteristic sensing mathematical model of actuator plunger vice.The load characteristics of the canopy along the length and width direction of the hydraulic support were deeply investigated.The influence mechanism of eccentric load condition on the canopy,pin shaft between the canopy and shield,front linkage,rear linkage and the specific pressure of base in the width direction of the hydraulic support was analyzed,the functionary mechanism of eccentric load condition on support load was revealed.Meanwhile,the influence of working resistance of the column and the equilibrium jack on the load characteristics of the hydraulic support canopy was further explored.It is pointed out that the increase of the working resistance of the column shortens the effective working range of the column,while increasing the working resistance of the euqilibrium jack has an opposite effect on it.In order to verify the feasibility of the sensing model models established in this paper,a multi-functional hydraulic support test system was independently developed,and an intrinsically safe wireless sensor network of single hydraulic support was constructed based on Zig Bee technology,which consisted of Zig Bee coordinator,hydraulic support controller,wireless pin shaft sensor,wireless pressure sensor,and wireless inclination sensor.It was constructed to realize the comprehensive perception of the posture and load of the hydraulic support.The test research of the working length of actuator,the posture of floor and roof,the loading position of the canopy and the liquid supply pressure on the posture and load characteristics of the hydraulic support were carried out based on the multifunctional test rig.The feasibility of the mathematical model was verified by experiments,which provided a reference for intelligent sensing technology of hydraulic support.This research systematically investigated the influence mechanism of supporting posture,the friction of actuator plunger vice and partial load conditions on the the load performance of the hydraulic support under the complex condition,which enriches and improves the sensing method of the posture and load characteristic of hydraulic support under complex conditions,realizes the comprehensive sensing of the posture and load characteristic of the hydraulic.The comprehensive sensing of the pose and load characteristics of hydraulic support under complex working conditions is realized,which provides theoretical basis and technical guidance for intelligent sensing of hydraulic support. |
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