Development Of CNC System For Leather Cutting Machine Based On OMAP-L138 & FPGA

Leather industry is one of the pillar industries of light industry in China. As a leather products production and consumption power, it puts forward urgent demand for special flexible material cutting equipment with the rapid development of leather industry. However, The majority of Motion controller and Motion control card in the market are general. Due to the closure of the underlying algorithm and hardware architecture, the development of special Computer Numerical Controller (CNC) systems and control algorithms for flexible materials processing is not easy to be developed. This paper design an embedded CNC system for leather cutting machine based on OMAP-L138+FPGA hardware platform begin with processing of flexible material, researching on the underlying hardware circuit design, cutting and transplantation of embedded Linux operating system, the NC application development and dual core communication.The overall design scheme of the system is established according to the analysis result which is based on the requirement analysis of the all functions of the CNC system for leather cutting machine. As the hardware platform of the system, OMAP-L138 contains ARM core and DSP core. ARM transplanted embedded Linux kernel is in charge of non real-time tasks. DSP transplants real-time operating system DSP/BIOS to deal with calculation work of look-ahead and interpolation, whose real-time requirements are relatively high. There are high speed IO and low speed IO are designed in the FPGA. They are used for the output pulse signal and control signal respectively.The system circuit is designed around the main control chip. In the main control unit, the peripheral circuit design is carried out for the OMAP-L138. Circuit module need to be designed includes:power circuit module, communication interface circuit module (network port, serial port, EMIFA, USB, etc.), and human-computer interaction device circuit design (LCD LCD screen and touch screen). Circuit is designed for the high and low speed IO interface in the transit board unit. Circuit module need to be designed includes:optocoupler input and output circuit, the power amplification circuit, signal differential circuit and sampling circuit of encoder.In terms of non real-time tasks of the CNC system, the program of ARM which designs four threads are used to process network data transmission, human-computer interaction, files parsing and instruction and data interaction between ARM and DSP. Beside, the paper design the data structure used to store the results of files parsing, and make an overall plan for the use of the memory space.As for real-time tasks of the CNC system, the control algorithm of DSP creates three tasks and setting the priority of tasks respectively as well as a timer interrupt. Three tasks were used to speed look-ahead planning, interpolation pulse calculation and the communication with the ARM core respectively. When reaching the upper limit of timer, interpolation calculation result will be sent to the FPGA. In addition, a special communication protocol is designed, which is used for data exchange between DSP and FPGA.In order to solve the problem of dual core communication, the paper use DSPLink, a set of communication components provided by TI Company, to design a dual core communication program for ARM and DSP to interact with data and instructions. To implement processing data transmission, the communicated method used for reading and writing large data is designed based on PROC component. The message queue accomplish the transmission of processing instructions, which based on MSGQ component and POOL component.Finally, the experimental results show that the advantages of this control system include high cutting efficiency and smoothing cutting contour curve by making an all-round test on the leather cutting machine whit the CNC system. The feasibility of the system hardware and software design and the stability of the control algorithm are verified.