An ARM-based Multi-channel CNC Solution for Multi

CIRP HPC 2016 June Prof., Dr. Sc. Sergej N. Grigoriev Prof., Dr. Sc. Georgi M. Martinov phone: +7 499 972-94-40

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An ARM-based Multi-channel CNC Solution for Multi-tasking Turning and Milling Machines

 ARM (Advanced RISC Machine) processors are used today to create:  stand-alone PLC controllers;  specialized or remote control panels, connected to the CNC as terminal client;  low-cost two-dimensional CNC for laser or waterjet cutting;  uncomplicated machine tool and robotic control systems;  …  Serious research on the applicability of the embedded CNC devices for controlling multi-channel and multi axis machine tools is still to be developed;  Single board computers based on ARM-processors shows a steady increase in computing power (processor speed, number of cores and memory space): Name

CPU

RAM

Ethernet

Price

Cubieboard 3

ARM Cortex-A7 dual-core 1 GHz

2GB DDR3

1xRJ45 1G Ethernet

$89

Raspberry Pi 2 ARM v7 quad-core Cortex-A7 900 MHz

1GB SDRAM 1x RJ45 10/100

Odroid-XU4

1xRJ45 1G Samsung Exynos5 octa-core ARM (Cortex2GB LPDDR3 Ethernet, WiFi A15 quad 2.0 GHz, Cortex-A7 quad 1.3 GHz)

Cubieboard 4 (CC-A80)

A80, ARM big.LITTLE octa-core (Cortex-A15 quad 2.0 GHz, quad Cortex-A7 1.3 GHz)

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2GB DDR3 2

1xRJ45 1G Ethernet

$35 $74 $125

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State of Art

Parameter

© Moscow State Technological University «STANKIN» 1930 – 2016

The kinematic scheme of NAKLON 535 machining center

Value

Working area (diameter/length) ≤ 535 x 1 000 mm Working feedrate Fast movement Machining accuracy

≤ 6 000 mm/min ≤ 25 000 mm/min 4 µm

Cutting tools

2 x 12

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CNC network architecture of NAKLON 535 machining center

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NC kernel models of virtual machines for PC-based and ARM- based solutions

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Servo drives

Raspberry Pi 2

Buscouplers

Standard operator panel

Standard machine control panel

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Parameter

Value

MTBF (Mean Time Between ailures)

> 2 000 h

EtherCAT cycle time PLC program cycle time

2 ms 2 ms

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Test equipment with ARM based NC kernel

ARM® Cortex™-A7 @ 1GHz x2 60 51,8 50

46,2 38,9

CPU load [%]

40

42,6

27,7

30

20

41,1

19,2

10

0 1x0

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1x1

1x2 1x3 1x4 Number of chanels and axes

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2x4

2x6

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CNC kernel drive system performance testing without PLC program

ARM® Cortex™-A7 @ 1GHz x2 Exynos5 ARM® Cortex™-A15 @ 2.0 GHz x4, Cortex™-A7 @ 1.3 GHz x4 Intel® Core™ i7 4500U @ 1,8 GHz x2 90 80 70 61,3

64

66,9

68,1

70,1

72,2

CPU load [%]

60 57,2 50 46

40

47,8

51,4

75

55,6

57

77,1

59

53,2

42,3 38

30 20

74,8

31

31

32,2

34,5

36,3

35

36,8

37

25 17

10 8

11

0 3,1 0

5000

10000

15000

Number of FBD elements

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20000

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CNC kernel with 6 interpolated axes and PLC programs containing up to 20 000 FBD elements

Laser interferometer Renishaw LX-80 - class 2 as defined in (IEC) EN60825-1.

Chanel 2 Axis X1 F 1000 mm\min Before correction > 12 µm After correction ~ 2.5 µm

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Axis calibration of NAKLON 535 machining center

Conclusions  The computing resources of the single board ARM computers present on the market are sufficient for performing the key functions of multi-channel and multi-axis machine tools.  The announced release of new ARM processors next year creates new prospects for the NC system, such as EtherCAT cycle time reduction up to 1 ms, increasing the number of control channels up to 4 and simultaneously interpolated axes up to 12.  Properly constructed architectural decision of NC software kernel allows porting it on a PC platform as well as on an ARM platform.

Additional information  Scientific journal AUTOMATION IN INDUSTRY, the topic of the edition is «Industrial automation - the backbone of digital manufacturing»  17th International Expedition for Equipment, Instruments and Tools for the Metalworking Industry METALOOBRABOTRA May 23-27 2016, Moscow

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Conclusions and additional information