Acceleration of parallel robot trajectory generation in FPGA

A trajectory generator is one of the most important part of CNC (Computer Numerical Control) machine control systems. It has to ensure the smooth tool movement and feed rate changes, which can be done with a limit imposed on the jerk. The paper presents an application of field programmable gate arrays (FPGA) to accelerate calculations needed for trajectory generation from G-code for a three axes parallel milling robot. The paper shows how to decrease the calculation time, preserving required accuracy, by augmenting the arithmetic-logic unit (ALU) of a microprocessor with custom instructions. The hardware implementation of the accelerator is described and results of calculations performed in an Altera FPGA chip are analyzed.