Design The Human-computer Interaction System Of Six DOF Parallel Mechanism Based On LinuxCNC Controller

At present, as the Stewart platform six degrees of freedom parallel mechanism has theadvantages of high rigidity, light weight and compact structure, it has been widely used incutting-edge industries, such as space robot, parallel nc machine tool and so on. In order tocomplete a certain space position or movement so as to realize the purpose and task ofmechanical system design, six degrees of freedom parallel mechanism must be under thecontrol of the controller, through the feed drive system. The openness and diversity ofparallel mechanism determines that its matching controller also should be open. Thoughstandard protocols and system framework of the open control system have been establishedboth at home and abroad so far, but they are not completely standardized or systematic yet.Traditional controller is difficult to obtain with closed functions, high cost, and complexhardware equipment. But the LinuxCNC controller running in the open source Ubutu10.04real-time operating system environment is open and could be free downloaded from itswebsite.With LinuxCNC controller under six degree of freedom parallel mechanism as theresearch object and taking the widely used cross-platform high-level language Python as adevelopment tool, this thesis develops and designs the3d motion model and virtual controlpanel by choosing the movement control cards and stepper motor and ball screw drive so asto build a six degrees of freedom parallel mechanism based on Linux CNC controller underthe human-computer interaction system. Its control commands could be performed by thestandard nc code generated by UG CNC module. The research contents of this thesis are asfollows:Firstly, the naming method of parallel mechanism is analyzed, and the degree offreedom is calculated based on the type of the Stewart platform6-UPS parallel mechanism.Positive and inverse solution algorithm for parallel mechanism is analyzed, by using thePython scientific computing algorithm inverse module establishment six degree of freedomparallel mechanism.Secondly, LinuxCNC software architecture, communication mechanism and the motioncontrol system are analyzed in detail. With the modular designed ideas and the spirit of opensource agreement, a specific function of the controller can be achieved by calling theappropriate modules. The hardware abstraction layer and its halcmd language are analyzed in detail. The language is a special tool for calling and configuring Linux CNC module,developing3d dynamic model, establishing the virtual control panel and connecting signaland pins of the hardware and software.Thirdly, Tkemc and AXIS two interface models that LinuxCNC controller itself bringsare contrastively analyzed and AXIS interface mode is selected based on the Pythonlanguage development.3d dynamic model is established through the use of PyOpenGLlanguage (Python+OpenGL). The connection between modules is established by thehardware abstraction layer halcmd language. Based on these, under the AXIS interfacemode, through the input of nc code and using the kinematics inverse solution algorithm, theplatform motion of six degree of freedom parallel mechanism and the pole’s change posturecan be observed intuitively and vividly.Fourthly, under AXIS LinuxCNC controller interface mode, the virtual panel is addedthe custom design. Using PyVCP (Python)+XML language to build the virtual controlpanel, and through the hardware abstraction layer halcmd language to establish theconnection between the modules, after the hardware devices connects to the power supply,the running status of the hardware could be directly observed on the virtual control panel.The design methods and procedures of the touch screen control interface are analyzed byusing GladeVCP.Lastly, on the basis of the3d dynamic model and the virtual control panel realized inthe previous sections, and by configuring the software and hardware for the LinuxCNCcontroller and choosing stepper motor and drive system, this thesis attempts to design thesix degree of freedom parallel mechanism the human-computer interaction system based onLinux CNC controller.