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MCAO @ ELT ESO-INAF cooperation Bologna - July 11th, 2002 Microgate is an electronics engineering and production company. Contact: Microgate S.r.l. Via Kravogl, 8 I 39100 BOLZANO www.microgate.it email@example.com • Main activities • Adaptive optics and other scientific projects • Development, production and marketing of Timing systems for sports applications
MCAO @ ELT ESO-INAF cooperation Bologna - July 11th, 2002 Adaptive optics and other scientific projects MMT336 thin-shell adaptive secondary mirror LBT672 thin-shell adaptive secondary mirror ALMA – Atacama Large Millimetric Array VLT STRAP - System for Tip Tilt Removal with avalanche Photodiodes
MCAO @ ELT ESO-INAF cooperation Bologna - July 11th, 2002 • The internal capabilities cover the entire process of electronic systems design and manufacturing: • Control System Design • Electronic design of Microcontroller and DSP based devices • High speed optical communication and logic • Software implementation (focused on embedded software and ‘hard’ real time) • Integration of industrial control systems • Internal prototyping and manufacturing of small series • Management of the whole process from project and prototypes to little and medium size productions • Components procurement • Management of assembly and integration • Testing
MCAO @ ELT ESO-INAF cooperation Bologna - July 11th, 2002 • Microgate involvement and responsibilities in MMT336 and LBT672 • Control system design (in tight cooperation with Osservatorio di Arcetri) • Electronic design (HW & SW) of the real time control unit • Procurement, manufacturing, integration and testing of control system
MCAO @ ELT ESO-INAF cooperation Bologna - July 11th, 2002 Adaptive mirrors control electronics • Co-located sensors and actuators (de-centralized control system) • distributed computational power: several small computational units take care of a limited number of independent channels (two channels for each DSP) • but • Centralized feedforward concept provides fast response for each controlled mode • Modular system: the number of channels can be easily expanded, but not indefinitely
Feed-forward + + MCAO @ ELT ESO-INAF cooperation Bologna - July 11th, 2002 Commands from WFC @550Hz + + - k-th Curr. Driver + coil 40kHz local loop -3dB@56kHz DM Capsens Linearization DSP DSP of k-th channel
MCAO @ ELT ESO-INAF cooperation Bologna - July 11th, 2002 LBT672 control system • 6 crates (3x2), 14 DSP boards + 1 communication board each • 8 channels controlled by each DSP board, 4 DSPs/board • 112 channels/crate • DSP type: ADSP 21160, 180 Millions multiply and add operations per second, 32x32 = 40 bits floating point • Total computational power: 128 Gflops, 64 GMACs/s • Sensor bandwidth: increased form 26 KHz (MMT) to 90 KHz • Actuator current driver bandwidth: 56KHz, OK ! • Sensor noise: measured noise on LBT sensor at same level of MMT (~ 4nm RMS @ 50µm gap) • Thermal stability (air not considered): 0.34nm/°K
MCAO @ ELT ESO-INAF cooperation Bologna - July 11th, 2002 LBT672 communication • Adaptive secondary control system connected to the Slope computer by means of two fibers • Daisy chain concept (can be easily expanded) • DMA access to the whole memory of all DSPs • Efficient burst data transmission/reception • Dedicated communication commands for MIMO filtering ... Comm. board Comm. board Comm. board Slopes RX Fiber Fiber Fiber Fiber Fiber Fiber (fast link) Link Link Link Link TX Link Link In Out In Out In Out Crate 1 Crate 6 Crate 2 Ethernet diagnostic link (no real time)
MCAO @ ELT ESO-INAF cooperation Bologna - July 11th, 2002 Practical issuesLarge production, configuration, reliability… • The electronics design is suitable for large production (actually, it can be only produced with automatic machines) • To improve maintainability, the system can be fully reconfigured remotely, through Ethernet (true for Software and Hardware configuration of the system) • Embedded system monitoring: • Board temperature • Actuator status • Power supply • Voice coil motors are fail safe !!! • Automatic testing already for LBT672 production run
MCAO @ ELT ESO-INAF cooperation Bologna - July 11th, 2002 What does limit the number of actuators ? • For a defined configuration of the electronics (communication speed, type of DSP, number of DSP per channel): • tRTR-MIRROR NCHANNELS • in fact • Communication delay NCHANNELS • Feedforward computation delay NCHANNELS • For LBT electronics: tRTR-MIRROR / 1000act = 22µs • (external RTR)
MCAO @ ELT ESO-INAF cooperation Bologna - July 11th, 2002 Impact of thin-thick mirror technology on electronics • Computational power and communication: no impact • Capacitive sensor: thick technology implies large gaps to be measured, but larger armature area available • Control • Large gaps reduce damping due to air viscosity. Remedy: increase control bandwidth so that electronic (derivative) damping can be introduced. Driver and capacitive sensor improvements currently under test. • Current driver • thick technology power estimate: 3 NRMS, 9WRMS / actuator • Typical efficiency of linear driver: 50% • Non-linear driver (PWM) would allow to save hundreds of KW of power.(Still open development for LBT !)
MCAO @ ELT ESO-INAF cooperation Bologna - July 11th, 2002 Power dissipation • Conditions • =0.55µm, r0=0.15m • Mirror flattening RMS force = 0.02 N @ t=1.8 • Coil efficiency: 0.5 N/W • Dynamic not considered !
MCAO @ ELT ESO-INAF cooperation Bologna - July 11th, 2002 Impact on system design and interfaces (LBT672) • Mechanical • Single interface flange to the alignment system • Double-crate size (224 channels): 405x305x110 (WxHxD) • Cooling • Two manifolds: 28 l/min coolant flow, p ~ 1.5 bar @ 10°C (TBC) • Electrical • ± 48V @ 35 A (three cables) • 3 digital signals • Data • 62.5/125 µm fiber connection (2x TX + 2x RX), 2.125 Gbit/s each • 62.5/125 µm fiber connection (6x TX + 6x RX), 1.25 Gbit/s or 100 Mbit/s each, for Ethernet diagnostic connection
MCAO @ ELT ESO-INAF cooperation Bologna - July 11th, 2002 Final considerations • The control system currently under development for LBT can be used for ELT adaptive optics up to ~5000 actuators per subunit (~100µs delay).Modularity of the system will allow to maintain essentially same design. • The control system shall be able to provide artificial damping for operation at large gaps. Dedicated hardware to provide this function is currently under test. • Power dissipated by the current driver shall be limited, particularly for thick shells and very large number of actuators.
MCAO @ ELT ESO-INAF cooperation Bologna - July 11th, 2002 LBT672 schedule • P45 engineering model • Fall 2002 electromechanical integration and testing (MMT electronics, new capacitive sensors and distribution boards) • Winter 2002/2003: LBT electronics testing • LBT672 #1 • electromechanical integration: Fall 2003 • Optical test in Arcetri: Winter 2003/2004 • LBT672 #2 • electromechanical integration: Winter 2003/2004 • Optical test in Arcetri: Spring 2004