CNC system of the 5-axis hybrid robot for milling

• Controller architecture for an unconventional milling machine was developed
• Implemented as a multiprocessor system in a single FPGA chip
• Calculations are accelerated by custom arithmetic circuits
• Algorithms implementation details are provided
• Experimentally confirmed correctness of 10 kHz sampling operation

The paper presents architecture and a FPGA based implementation of the dedicated CNC system for 5-axes milling machine. The hybrid structure of the machine, consisting of the parallel manipulator and the tilt rotary table, required development of a specialised controller, called CNC system. The CNC system is composed of the two main parts: Human-Machine Interface (HMI) and Numerical Control Kernel (NCK). The NCK consists two soft-processor units, equipped with coprocessor's instructions, performing calculations on floating point numbers, and a dedicated hardware block, which integrates the system. The priority functional requirement is the sampling frequency of 10 kHz for all modules. Another aspect of the paper is the realization of coprocessor algorithms for arithmetic, trigonometric and other functions. The paper shows results of computing test efficiency and the maximum calculation error for a trajectory generated from G-codes. The results prove fulfilling all requirements. Finally, the conclusions and directions of future works are presented.