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M. E. Bräuer 07.05.2005The Control System for the X-FEL Undulators
The Control System for the X-FEL Undulators
Martin E. Bräuer, DESY Hamburg, HASYLAB
Outline: • Requirements
and Concept• Components• Our Prototype• Measurements• Summary
M. E. Bräuer 07.05.2005The Control System for the X-FEL Undulators
Requirements and Concept
• synchronized gap movements• comprise the modular setup =>
cells• high reliability• allow complex movement-
schemes• movements with high dynamics• long-term availability of
components
Cell
Segment:• 4 synchronized motors• gap: ≤ 1µm precision• single-motor operation
(“taper”)• speed: (0,02 .. 20)mm/s• force: ≤ 160kN
Segment
cell i-1 cell i
Intersection
Intersection:• ≤ 5 control variables
(i.e.: position, current..)• value: f(gap) • synchronized: ≤ 10 µm
gap• cycle-time: ≤ 5 ms
M. E. Bräuer 07.05.2005The Control System for the X-FEL Undulators
.. complex movements
Various “patterns” need maximum flexibility !
Taper-mode:
Diagnostics: Have ≥1 device switched-on at a time
=> Move quickly (>30 devices in an undulator!)
M. E. Bräuer 07.05.2005The Control System for the X-FEL Undulators
Industrial Controls:• robust• productivity• fast markets (10y = an age !)• cheap• a huge market: O(200) German
companies &• safe
$/a91055
Secure investments:• Truly open standards (CANopen,
SERCOS, RS232, EtherCAT)• Vendor independent• Multi-Vendor environments
Industrial components
M. E. Bräuer 07.05.2005The Control System for the X-FEL Undulators
Motors
Stepper
• Rotating magnets
• Static coils
1/1 step
1/2 step
1/4 step
1/8 step
1/16 step
1/32 step
1/64 step
Stepper: Assume a rotor following
encoder
currentvelocityposition
Servo-controller
encoder
? ??
fieldbus
Servo: Measure the rotor angle
Synchron-Servo-Motor:
1kW !1€
• From the automation market
• 300 .. 1000000 W
• Cheap, robust, well understood
M. E. Bräuer 07.05.2005The Control System for the X-FEL Undulators
Encoder Systems
Measure the linear position of each axis=> The encoder determine the
accuracy/resolution
• Open, incremental encoders => reference-switch/mark needed
• Optical reading of a ribbon
• 20µm period length => sin,cos Signal @ 1Vpp
• Electronic “oversampling” (x4096) => linear “steps”
• Resolution: ok, precision?
• Operating them ‘close’ to a beam
• Singular point of precision
• Mounting?
• ULE (ZERODUR-like) mountings => compensate thermal deviations
M. E. Bräuer 07.05.2005The Control System for the X-FEL Undulators
Control-System
… …
cell i
high resolution encoder
motors
(multiturn) rotational encoder
local control CPU
(general network)
real-time network
coilsmotors (i.e. stepper)
I/O signals (fieldbus-devices in cell (opt.)Dezentral periphery
prec. analog out
(SERCOS drives for Intersection)
moto
r co
ntr
olle
r and a
mp
lifier
Intersection
Intersection not fully defined need maximal flexibility
M. E. Bräuer 07.05.2005The Control System for the X-FEL Undulators
Safety issues
• Needed feature in industrial solutions• Bus sensitive to many errors• Robustness (no false alarms required
(HERA!)• Additional measures allways possible
• Axis synchronization has a high priority in commercial systems
• “It is all software” Yes, get this from professionals!
• We have to define procedures• No problems found yet• Commissioning phase “interesting”• Have to foresee a indiv. Taper• Several devices will be used in Petra III
InterlocksPersonal-safetyRadiation safety
To be defined later..
Total:4x 132kW
M. E. Bräuer 07.05.2005The Control System for the X-FEL Undulators
The Protoype
M. E. Bräuer 07.05.2005The Control System for the X-FEL Undulators
Hardware Details
Terminals: IO and Intersection
12mm
CPU
Controller / amplifier
Power / safety
4x PWM output4x 0..10v (0.01% prec.)4x stepper (one mounted)
M. E. Bräuer 07.05.2005The Control System for the X-FEL Undulators
Measured Data: Precision Encoder vs. Motor 1
Rotor (incl. offset to get picture)
1 Axis and master (thin)
0.5µm tsample = 1ms
Time [s]
pos
= g
ap/2
[m
m]
M. E. Bräuer 07.05.2005The Control System for the X-FEL Undulators
Measured Data: Precision Encoder vs. Motor 2
Rotors (incl. offset to get picture)
4 Axis and master
50µm
150µm ! one bad spindle (known)
Encoders & servo-loops: loose requirements on mechanics
M. E. Bräuer 07.05.2005The Control System for the X-FEL Undulators
First stress tests
High precision – with
137mm ‘walk’
0.5µm
one axis
all axis
M. E. Bräuer 07.05.2005The Control System for the X-FEL Undulators
First stress tests
17x open/close cycleswith highest speed
0.5µm
v: 272mm in 12.5s
M. E. Bräuer 07.05.2005The Control System for the X-FEL Undulators
Summary
• First electro-mechanical prototype working
• System got up successfully (HarWi / MTU still there)
• Found a good supplier
• Measurements ongoing
• No showstoppers found yet
• The control system can be used rather widely
• >10x faster than Profibus• Based on ethernet• Existing (support/interest by >170 companies)• Open (fully documented)• Have only 1 bus !• > 50µs tasks with I/O, 12000 dig. IO in 350µs,
100 Servos-Axis in 100µs
OutlookNew fieldbus: EtherCAT: