> One, introduction
Along with optoelectronic technology rapid development,
laser carving technology application scope more and more widespread,
the carving precision request is more and more high. Manifests
the laser material processing the level of development to have three
aspects the factors: First is the laser technology, namely
applies to the laser material processing laser component technology;
Second is the machinery, the control system which the laser
device processes and so on, namely laser processing equipment;
Third is the laser processing technological level. Because
the laser technology already was the very mature technology, whether
therefore carries on the effective control as well as the laser
processing technological level to the laser device becomes the laser
carving technology application the bottleneck.
At present, domestic specially produced the laser to carve the
equipment the factory to be very many, they compete changed by the
laser technology to the laser device and the processing craft active
control, whether the effective addressing following question, the
three dimensional graph multiple spindle linkage, the high speed laser
scan and the fast advancement do cause the vibration, the scanning
width size and the scanning precision, the laser synchronous scanning
and the reciprocation scans the dislocation, the complex algorithm and
the regular graph inserts makes up the question and so on, already
became the competition the key.
Second, based on DSP and FPGA design
In view of the above each kind of question, unifies many
years movement control the experience, we have designed based on
resources rich FPGA and function formidable DSP movement control panel
card - MPC03, in laser carving debugging, success solution above each
kind of question.
1. MPC03 card circuit design
Mainly has DSP, the FPGA two functions chips in the
MPC03 card, expanded many FLASH and the SRAM stored routine and the
data around DSP, every two FLASH and SRAM may altogether use 片
signal CS, the composition height double character 32 figures to carry
on read-write according to the main line, may enhance DSP and the
MEMORY correspondence speed, simultaneously was FPGA disposes EPROM to
save downloading the procedure. Connects the DSP local bus and
the PCI connection chip is the PCI bus control unit (the PCI bridge),
it has contained a 128KBit pair of mouth shared buffer memory sbm,
realizes the DSP local bus and the PCI system bus data exchange,
moreover has disposed a EEPROM stored datum for it, simultaneously
this card complied with namely inserts namely with the connection
design tendency, expanded the USB connection. This article
mentioned DSP and FPGA all are the low energy consumption, the low
voltage operation, the I/O signal voltage is 3.3V, but the essence
voltage is 1.8V, therefore disposed has been able simultaneously to
output 3.3V and the 1.8V two kind of voltages voltage regulators.
Please refer to the MPC03 card logic structure drawing.
FPGA resources sufficient, the natural price is higher than, can
the scene repetition program many times, may aim at the different
small batch customer the specific request, nimbly revises the design.
DSP has the high speed floating point calculation the ability,
and some inserts to in the S- curvilinear motion process data makes up
the algorithm, carries on operation processing, gets rid to the PC
machine dependence, and processing data real-time and FPGA
correspondence. PCI connection use quite universal, main line
resources rich, the communication speed block, the addressing space is
big. The USB connection may realize the off-line working, does
not need to dispose PC machine for each block card, industry field use
convenient, the cost is low, conforms to the time development
tendency.
2nd, each kind of function realization
Because this plan determination appropriate, may realize
four axes functions on each piece of FPGA chip quite same not less
than but each other mutually independent operation, can realize the
multiple spindle linkage, regarding the plane figure and three
dimensional graph processing, may use two axes and the three axle
linkage.
In the scanning, based on the opening RAM area, uses the
position chart picture element control, not only has solved great
width graph processing, moreover has realized in the synchronous
scanning, increased the scanning precision, has guaranteed the picture
carving quality.
(1) uses the S curve realization steady high speed movement and
the fast advancement
In high speed reciprocating motion and fast line of
advancement process, if does not add technical processing, like the
trapezoidal chart shows, in the acceleration very big high speed rate
process, can appear the vibration, the impact, the graph can appear
the irregular dislocation, is serious when can appear the similar
corrugated distortion. If reduces the acceleration, then the
speed-up time (t2 - t1) very is big, because adds the work area in the
high speed section (FH uniform speed section), like this creates the
effective processing width to reduce. In order to solve this
problem, uses the S curve in the variable motion, may cause the
movement in the very short time, to is high speed by the low speed or
by high speed gently transits to the low speed. After the scene
repeatedly experiment, on the identical equipment, may the big
enhancement working efficiency and the graph processing quality. 
(2) use position chart picture element control, guarantee
synchronous scanning and scanning precision
In order to save the massive scannings data and achieved
the synchronous scanning the goal, we ingeniously used 2MBit which in
FPGA set the block RAM resources to save each line of images data.
In this design, we opened 9 address wires addressing 32Bit the
data bus connection RAM area, namely 16KBit. If each scanning
picture element is 0.1mm, according to highest scanning precision,
then theoretically scans the width to be allowed to achieve 1.6m.
Scanning from low position address to top digit address, from
each line of low positions to top digit succession. Each
scanning pulse, a step of 进电 machine actuation stirs up baldly
front goes a step further, simultaneously reads from the RAM area
takes a graph data, and according to reads the fetching according to '
1 ' or ' 0 ' the condition decided whether switch light. Because
DSP each time reads in line of graphs data to the FPGA RAM area
512×32Bit, therefore in to these 16KBit data processing period, DSP
does not have again to write the data to FPGA. Not only greatly
enhanced the laser device working efficiency, moreover also had
guaranteed the scanning synchronism, scans the overall dislocation
regarding the reciprocation which appears, for carried in software
reverse compensates has also provided the feasibility.
When synchronous scanning, in order to increase the scanning
precision, the improvement picture quality, we increased 8 lasers
controls register LCR, through establishes LCR the size (0 ~ 255),
achieved the enhancement scanning precision the goal, please look at
the following analysis:
The position chart picture element control laser switch exists
question
Gives an example to analyze: The supposition
position chart data is 1,010, facula diameter for Ф 0.1mm, single
picture element pulse several 5, then step enters the pulse and the
laser scan as follows:
May see from the above graph analysis: If completely acts
according to the position chart picture element control, pulse of
laser light width for single picture element pulse number decision
width; As a result of the laser facula diameter existence,
theoretically is opening stirs up the luminous spot the position to be
able to appear "has cut" the phenomenon, namely the picture element is
' 1 ' the spot can eat the next picture element is ' 0 ' spot.
The laser opens, closes the detention the influence:
1. if the laser opens the detention, the pass detention is
equal, the actual carving graph will translate;
2. if the laser opens the detention > to close the detention
(开 to be slow, Guan Guangkuai), "has cut" can reduce;
3. if the laser opens the detention<关延迟（开快关光慢），过切”会增大?BR> Pulse of laser light width control
Above in order to reduce or eliminates "has cut" the
phenomenon, when reigns the chart picture element is ' 1 ', should
send out a as far as possible short pulse of laser light. This
pulse of laser light width and stirs up the fluorescent tube by the
laser actuation power source to open, to close the characteristic
decision. But at present can accurately produce the development
which the laser switch retards the data not to be many, may use
experimental the method determination pulse of laser light width.
Refers to attempts: In the picture element is ' 1 ' first
step enters the pulse to drop along triggers laser ON, use counter
time delay TL (after the laser control register LCR low 8 hypotheses),
shuts off the laser (OFF). Such pulse of laser light width may
adjust, but is not the single picture element pulse number width.
Thus, through the control pulse of laser light width, when the
picture element is ' 1 ' sends out to stir up the luminous spot (but
is not a line segment), may reduce above ' has cut ' the phenomenon,
improves the laser carving quality.
3rd, system antijamming measure
The disturbance is in the industry scene and the
practical application the inevitable phenomenon, the system resistance
to interference is the system reliable important symbol. The
printed wiring board is the component, the holding wire, the power
line highly the aggregate, it designs the quality resistance
disturbance ability influence is very big. Has mainly used below
the antijamming measure in this design:
(1) number, the mold electric circuit separates: Uses the
ordinary light pair or the high speed light pair in the internal
circuit and among exterior machinery input signal carries on the
isolation, separates theirs power source and the grounding.
(2) disposition 去 electric capacity: In the essential
place disposition 去 electric capacity, like mains input
termination 0.1 ~ 47 mu F pastes the piece electric capacity, the
worry eliminates the different 频率?disturbance, each primary
device power source and the place end all dispose 0.1 mu F to paste
the piece electric capacity and so on.
(3) disposition numeral filter: Regarding the FPGA chip
several signals, the replacement, report to the police, return to zero
and so on, can cause the system replacement or stop, in order to
increase the system reliability, must add the digital filter, may use
the software realization in this, enable these signals with the VHDL
language to pass through several level of D trigger (progression in
accordance with the situation to decide), again carries on the logic
to all levels of signals and or the logical or. Third,
concluding remark
Along with the optoelectronic technology and the large
scale integrated circuit unceasing development, the laser carving will
certainly to obtain a more widespread application, then impels DSP and
FPGA in the correlation domain application and the development.
In the future which may foresee, the DSP technology and FPGA
will certainly in astronautics, the correspondence, the laser carving
and so on in many domains to obtain a more widespread application,
then is impelling these technical further development.
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