【正文】 s presented by analyzing to the performance of haulage and velocity modulation and the constant power control to coal mining machine in the real work. Controller outputs control signals which control touch sensing forcefeedback devise base on magnetorheological fluid by sampling current and rotate speed signals of cutting motor of coal mining machine. The manipulator adjusts haulage speed of coal mining machine to force the motors to operate approximately with rated power according as resistance touched by handle. The results of simulation and experiment indicate that the method can enhance obviously cutting efficiency of coal mining machine and void overload operating. The structure of the control method is simple and actualizes easily, so its outlook in application is good.Keywords: Touch sensing forcefeedback。 magnetorheological fluid。 Coal mining machine。 Power control1 IntroductionWith energy industry rapid development, the power of coal mining machine increases from several dozens kilowatts to more than 2000 kilowatts presently. The growing of coal mining machine work efficiency enhancement is emphasized. At present, coal mining machines operate under the constant power through adjusting haulage speed. In the existing product, according to the related parameters and the experience, the manipulator adjusted the button of the manipulator to set haulage speed (limitation value). The machine actualizes automatic control and operation under full load of machines. In the practical application, because of the plex of the coal beds and the deficiency of manipulator39。s experience the coal mining machines is in frequently operating under underloads, occasionally overloads. Operation under the longterm overload can accelerate its aging and increase the frequency of breakdowns, which cannot play its potency in application. Therefore, the more humanbased operating mode is needed to settle the above questions radically. The research of the ability of humanity acquisition information indicates that the sense of touch is the most important feeling except the sense of vision and hearing [1][2].Comparing with the visual feedback, the sense of touch not only can distinguish the size and the shape of the object, but also can distinguish hardness, quality of material, smooth degree and superficial mechanism, and so on. Magnetorheological fluid provides a new direction for development of the sense of touch feedback system because of its unique flowchanging characteristics and good controllability [3] [4].In order to achieve the precise and effective control to haulage speed of the coal mining machine and realize it and the power control to achieve the best efficiency, on the base of magnetorheological valves which we develop independently, a kind of constant power control method of coal mining machine is designed based on touch sensing technique and magnetorheological fluid, using special performance of magnetorheological fluid一a new intelligent material.2 The Sense of Touch ForceFeedback Device Based on MagnetoRheological FluidWhen the hand of a man fetches an object, a moment is produced in the joint after the muscle of the fingers contracts。 this moment causes the finger to produce a force. If this force affects on the surface of the object, the object produces a equal size, the opposite directional force to the finger, this force extrusion epidermis of the fingers, and stimulate sensory nerve cell, the stimulation signals are passed to human39。s cerebral cortex (nerve center). By analyzing these stimulation signals, the man hand can feel the force. This will form sensation of the force sense. During the conventional passive forcefeedback devices working, when manipulator by remote control installment fetches an object, the forcefeedback device produces a damping force to prevent the finger to do further grasp movement, according to the force signals transmuted by the longdistance manipulator. Here, the size and direction of this damping force have the same direction and the size of linear relation to the force produced by the real object to the fingers when a real object exists, which makes man feel that seems grasp the real object. Working Models of MagnetoRheological FluidMagnetorheological fluid is the aerosol liquid which is formed by dispersing magnetic particles with the high saturation magnetic induction in nonmagnetic carrier liquid. Iron particles are magnetized when the role of the magnetic field, iron particles arranged along the direction of magnetic field. The mixture in seconds quickly turned into solid. Hundreds of KP magnitude shear stress can produce. It has better practical engineering value. The material phase change is not only rapid, but also reversible. Once the magnetic field pletely removed, and the material restores fluid. What is more important is magnetorheological material has controllability. The degree of phase change and size of interior shear stress can be controlled by the magnetic the magnetic field, Magnetorheological Fluid change Newtonian fluid of free flow into viscoplasticity body of certain yield shear strength, After removing the magnetic field, Magnetorheological Fluid restore the free liquid state. This is Magnetorheological effect. Magnetorheological effect has the following characteristics: (1)Conversion is reversible。 (2) Conversion is controllable。 (3) control Conversion only controls the current signal strength of the magnetic induction。 (4) control Conversion only response millisecond time。 (5) energy of control Conversion is very low [3] Designing of MagnetoRheological ValveMagnetorheological valve is shown as Fig. 1. The valve body is made of nonmagnetic material. One end of it connects to working connection and another end to a piston cylinder body, which constitutes a seal connect cavity with magnetorheological fluid in magnetorheological fluid valve work, the magnetorheological fluid i