The Dynamic Analysis And Control Of The Articulated Drived 3-DOF Swaying Platform

The Articulated Drived 3-DOF(3-DEGREE-OF-FREEDOM) Swaying Platform is the 3- DOF parallel robots, belong 3-RRS parallel robots. it is in recent years in great demand of robot studies. The organization of parallel robot, imitate vitality weapons, aerospace, marine project, military affairs and traffic and other aspect to have extensive prospect. The parallel robot features high rigidity, great load-carrying capacity, small error, high precision, small self-weight/load ratio, good dynamic behavior and easy control. So expending the field of application of robots. This paper is based on 3-DOF Swaying Platform for the study, and focusing on the dynamic analysis and control.In this paper, we analysis the research of parallel robot and build up a computer-control system of 3-DOF Swaying Platform, 3-DOF Swaying Platform is composed of five units according to the function, which are controlling computer, electrics-hydraulic servo unit, execute framework unit, hydraulic system unit, feedback unit.In studying on the 3-DOF Swaying Platform, the kinematics and dynamic model of 3-DOF Swaying Platform is the base of coming up controlling. It is important to study on the dynamic model in designing the kinematics controlling system. Positive and negative solutions are main content in dynamic model. It is easy to solve the negative solution. But the positive position is a difficult problem. And robot motion control actuator is the inverse calculation, therefore more suitable for parallel institutions online speed and position adjustment. As the dynamics are complex solutions, we must establish control system is not required for dynamic analysis it is only inverse dynamics analysis to establish control system model.The 3-DOF Swaying Platform, frame P-xyz is fixed on the movable platform, P is the mass center of the the movable platform, frame O-XYZ is fixed on the base platform, O is the mass center of the the base platform .establishing a solid frame with the coordinate system. To facilitate the analysis, there was a need to build several components-fixed coordinate systems. The 3-DOF Swaying Platform components for position analysis, velocity and acceleration analysis, establish a system of inverse dynamics equations, Drivers draw for the next phase of outrigger platform coordinates the driving equation:τ_di =τ_dui +τ_ddi-(L_bai×f_ai)·x_bi (i=1,2,3) where:τ_dui = (( I_ui-m_ui [ L_cbi×]²)(ω_bi+ω_ci) + (ω_bi +ω_ci)×((I_ui-m_ui[L_cbi×]² )(ω_bi+ω_ci) -m_ui r_ui×(g-v_ui))·x_biτ_ddi= (I_diω_bi +ω_bi×(I_diω_bi) - m_di r_di×(g-v_di))·x_bi where:where I_dio is the inertia moment of the up link expressed in frameBi-xbiybizbi,and L_cbix,L_cbiy,L_cbiz , are the three coordinate components of vetctor Lcbi .Because the unsymmetrical vat is always applied in engineering, in this system we must build the mathematics model of it, the unsymmetrical vat has advantage of small size, easy manufacture and lower cost, so it is popularly applied in hydraulic pressure servo system especially in position control system. The kinematics property of valve-control hydraulic characteristic lies on valve, vat and load. Considering centralized parameters, generally load is presumed to mass and viscous damp and spring single freedom system. Now according to the properties of single perch hydraulic cylinder with four-channel valves-control, we only discuss the working condition of piston perch extends outside.Sought by the use of hydraulic cylinders and the transfer functions of the servo valve transfer function, the system reached the open-loop transfer function:It is simple that PID controler have structure , stability can be good , reliability is high , its control principle have perfected maturation with control technology, and for the design and staff on-the-spot engineers know wait for advantage. But conventional PID controler meets parameter change with a group of regular constant PID parameter, disturb wait for numerous change factor, obviously the control that is hard to get satisfaction effect. For improvement control effect, difference adopts vague controler and Lu strong controler.Vague logic control is to make computer have active and intelligent control method, what the behavior parameter design method that relies on system with traditional controler is not same is that vague controler relies on the experience of operator. It summarizes the practice experience of skilled operator and describes, and express with computer language.Fuzzy PID control is a digital PID controller based on fuzzy set theory, Under the system deviation and deviation change the size of real-time change PID parameters, It is clearly more in line with the object about control law. Quality control is better than digital PID control, particularly in reducing excess capacity and shortens the transition process as there are the more obvious effects; the algorithm is easy to implement on a computer. Applicable to the real-time control.This computer-controlling system is based on Windows 2000 multitask environment. Windows 2000 are made up of kernel, VxD, a mass of DLL and some application programe. The kernel and VxD run in protected mode Ring 0 level named kernel mode, common application programe and DLL run in user mode Ring 3 level named user mode. If you want to operate the hardware in operation system Windows 2000 the application programe must run in kennel mode. In fact this is VxD, the code run in user mode operate hardware all by kernel mode code. In real-time controlling system, time is the valuable resource. All task in controlling system include input, output, calculate and data transfer must complete in finite time. If the reasoning and calculation is right depend on not only the logic but also the time. So if you want to complete the controlling task, you must acquire the accurate time. This paper expatiate the clock mechanism of operation system by general timer, multimedia timer and high precision timer which need the hardware. You can choose you timer according to your practical matter. This system select the third timer, in hardware, prepare the clock circuit, in the controlling card there is a 8254 timer which is the system time signal, it manager all task by interrupt mode. It can ensure the precision time and change the timer period by programming. From the results of the experiments, control effects are very well.