A hardware–software system for coordinated multi-axis control based on a non uniform rational B-splines interpolator applied to industrial computer numerically controlled machines

Abstract

Motion controllers are widely used in many mechatronic applications such as computer numerically controlled machine tools and robots. These applications demand the use of high performance controllers. Some desirable characteristics in motion controllers are coordinated multi-axis control, smooth movements, and advanced interpolation methods. An important manufacturing aspect involves the production of a workpiece in a free form or using the parametric surfaces in modern computer aided design/computer aided manufacturing systems. The use of parametric curves and surfaces has become standard due to their ability to represent objects having complex surfaces with less data. Another mandatory characteristic of motion controllers is the real-time operation. The contribution of the present work is the design and implementation of a hardware-software system for multi-axis motion control featuring non uniform rational Bsplines interpolation. Advantages over other reported works are the hardware implementation which allows the application to real computer numerically controlled machines; also the parallel processing permits the incorporation of additional modules to form an integral system without dependence on external devices. Two experiments were carried out in a retrofitted-to-computer numeric control milling machine in order to show the efficiency of the developed system.

Research of the real-time interpolation based on piecewise power basis functions

“…With the power basis functions, C ( u ) , C ′ ( u ) , and C ″ ( u ) can be quickly computed, and their latencies are 117, 93, and 69, respectively. However, with the DeBoor-Cox algorithm, 4 the latencies of calculating C ( u ) , C ′ ( u ) , and C ″ ( u ) are 456, 288, and 233, respectively. Compared with the DeBoor-Cox algorithm, the latencies of the proposed curve conversion algorithm can be reduced by about 71.1% on average (as seen in Table 4).…”

“…Proposed algorithm (latency) 117 93 69 DeBoor-Cox algorithm 4 (latency) 456 288 233 length calculation. Then, the look-ahead ACC/DEC module obtains the velocity profiles.…”

“…Considering B-spline computation complexity, for instance, the DeBoor-Cox recursive algorithm is utilized to determine interpolation points of a B-spline curve. 4 However, when this algorithm is adopted to compute the derivatives directly, 5 it is inevitable to compute the B-spline basis functions repeatedly, which leads to redundant computation. Grabowski and Li 6 proposed an iterative formula to implement the DeBoor-Cox formula.…”

FPGA-based hardware CNC interpolator of Bezier, splines, B-splines and NURBS curves for industrial applications

“…Also, there are several DSP developments for parametric interpolators and CNC controllers, being B-splines (Erkorkmaz & Altintas, 2001) and NURBS interpolators (Cheng & Tsai, 2004;Tsai, Cheng, & Cheng, 2003) the main reported techniques. In addition, FPGA developments of hardware/software architectures for tool path computation have been proposed for spline (De Santiago-Perez, Osornio-Rios, Romero-Troncoso, Cabal-Yepez, & Guevara-Gonzalez, 2010) and NURBS (Cuenca, Martinez, Jimeno, & Sanchez, 2007;Jaen-Cuellar et al, 2012;Yau, Lin, & Tsai, 2006). Yet, these FPGA developments present the implementation of trajectory interpolation for a single interpolation technique.…”

SoC-based solution for multi-axis control systems using high-level synthesis

“…2–6 Particularly in the field of multi-axis systems, such as robot and computer numerical control (CNC) system, the HW/SW solution is a more appropriate choice. 7 The HW/SW system can be classified into SoC-based system and processors and programmable logic (PL) device system. Compared with the SoC-based system, the latter has the features of good flexibility and portability.…”