REVOLUTION PROJECT: PROGRESS IN THE EVOLUTION OF SOLEILMOTION CONTROL MODEL∗

S. Zhang†, F. Blache, D. Corruble, C. Kheffafa, YM. Abiven, SOLEIL, Gif-sur-Yvette, FranceS. Minolli, NEXEYA SYSTEMS, La Couronne, France

AbstractSOLEIL is a third generation synchrotron radiation source

located near Paris in France. REVOLUTION (REconsiderVarious contrOLler for yoUr motion) is the motion controllerupgrade project currently in progress at SOLEIL. It wasinitiated to maintain the facility operations by addressingthe risk of hardware obsolescence in motion control butat the same time making room for complex applicationsrequirements to face new high performance challenges. Inorder to achieve these considerations, SOLEIL’s strategymove was to go from a single controller for all applicationsto two motion controllers. A first Controller GALIL DMC-4183 was chosen to succeed the previous version DMC-2182. Both controllers can be integrated in the existingarchitecture with little hardware and software adaptationenabling full compatibility with the existing architecture. Asecond controller, Delta Tau Power Brick, has been selectedas a HIGH PERFORMANCE solution providing advancedfunctionality.

The CLASSIC controller upgrade is about to be completedand the integration of Power Brick into the SOLEIL controlsystem is ongoing. The system complexity is abstractedby embedding processing functions into low-level code andgiving end-users a simple high-level interface. The workdone to structure the interfacing and standardization of thecontroller are detailed in this paper.

CONTEXT OF REVOLUTION ATSOLEIL [1]

Motion Control Status and Upgrading MotivationsSOLEIL needs to upgrade its standardized GALIL mo-

tion controller in order to address two challenges: First, thecurrent motion controller used in SOLEIL is dated and inrisk of being discontinued and we must have an updatedproduct before this happens. Nevertheless, this is not ex-pected to occur in the next few years. Secondly, new motioncontrol applications demand a higher performance and moreadvanced features that can not be reached by our currentcontroller.

Strategy: Change ModelTo achieve the next three goals of "Increasing perfor-

mance, maintaining operational continuity, and controllingoverall cost", SOLEIL decided to replace the current model

∗ Work also supported by XT. Tran, M. Cerato, G. Renaud, E. Fonda andSAMBA Beamline staff, C. Engblom, Delta Tau Ldt., IMO JEAMBRUNAUTOMATION, Observatory-Sciences Ldt...† szhang@synchrotron-soleil.fr

of a "single and universal controller" by a model with twokinds of motion controllers:

• CLASSIC motion controller, mainly used and suitablefor "simple and classic" applications. This controlleris fully compatible with the existing hardware and soft-ware motion control architecture.

• HIGH PERFORMANCE controller, used in few cases,suitable for "complex and fast" applications. The hard-ware and software motion control architecture is de-signed to be close to the existing architecture for theCLASSIC controller.

CLASSIC CONTROLLER EVOLUTIONThe GALIL DMC-4183 controller was chosen to succeed

the current Galil DMC-2182. Its implementation needs somehardware and software developments which are currentlybeing done to make it compatible with current architecture.On the software aspect: a new firmware was developed byGALIL which includes the new "Continuous Closed-Loopon Stepper motors" feature. It was validated by SOLEIL byan operational application done on the monochromaters ofLUCIA and TEMPO beamlines. To use this feature, a newmicrocode (embedded code) was developed and validationtests are ongoing. For the hardware: in order to use thecurrent ControlBox rack (same size, same pinouts), an inter-face board (MIG-4121) has been developed which adapt theDMC-4183 to the internal pinout of the ControlBox rack.The integration in the rack has been validated and is nowoperational.

HIGH PERFORMANCE CONTROLLERSTANDARDIZATION

Controller ProductDelta Tau Power PMAC in the Power Brick LV-IMS for-

mat was selected for the new “HIGH PERFORMANCE”solution after a long evaluation process.

Figure 1: Power Brick LV-IMS.

Power PMAC is a general-purpose embedded computerwith a built-in motion and machine-control applicationwhich offers: powerful computing capacity, multi-axis syn-chronization, encoder processing, virtual control through

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kinematic equations, non-linear trajectories, built-in soft-ware PLCs (programmable in Power PMAC script and/or Clanguage) etc. Moreover, around Delta Tau products there isan international user community in large research facilities.

The Power Brick LV-IMS rack (see Figure 1) is now avail-able with a SOLEIL standard compatible connectivity formotors and encoders. It comes with the configuration of aPower PMAC CPU and 8-axis integrated amplifier circuitsfor 2-phase and 3-phase motors direct-drive. The number ofaxes can also be expanded through a MACRO fiber opticsnetwork. As an option, it can be configured to support dif-ferent encoder feedback protocols among a wide variety ofchoices.

Control ArchitectureFor reasons of consistency and usability we intended to

keep a control architecture as close as possible to the existingone. Considering the performance benefits of the product,most process functions are embedded into low-level to ab-stract the system complexity for the high-level software. Inorder to make the controller easy to use and maintain innormal operations, we developed some standard function-alities for the hardware low-level configuration and in theembedded software.

Figure 2: Power PMAC embedded system structure with anexample of motion system application.

High-level Software for User InterfaceIn order to structure the end-user interface, the software

high-level architecture shown in Figure 3 has been developed.The software consists of Tango devices for axis controls andgeneral rack controls. The rack controls communicate overthe "PowerPMAClib" and "DeltaTauLib" libraries.

The Tango device interface for the new HIGH PERFOR-MANCE controller is designed to be very similar to thestandard CLASSIC controller. A single Device Server

Figure 3: High-level software architecture.

"ds_PowerPMAC" including the main set functionality iscomposed with the following devices:

• Device PowerPMACBox for the controller and generaldata.

• Device PowerPMACAxis for driving physical axis.• Device PowerPMACComposedAxis for driving com-posed virtual axes (one device/CS).

To complete the functionality supply, some devices areplanned to be realized in the near future:

• Device RawDataViewer, a diagnostic tool providingread-only raw firmware data of Power PMAC for speci-fied axis.

• Device AppliParameter, a tool providing read and writedata of the controller for users to parametrize theirapplication-dedicated variables.

The Tango devices access the Power PMAC level through"PowerPMAClib", which encapsulates "DeltaTauLib"."DeltaTauLib" is supplied by Delta Tau to provide access tothe firmware and embedded "user" data via Ethernet [2]. The"PowerPMAClib" library, developed by SOLEIL, presentsin its interface the access to general controller functions (e. g.connection, status, temperature, operating time, reset etc.)and the axis control functions (e. g. position, speed, stopetc.). Within axis controls, the library makes the link to thedata structures stored in the shared memory of the controllerfor data exchanging and command settings. The informationin the data structures are accessed and updated from theembedded programs in parallel from the Tango devices.

Embedded System StructurePower PMAC uses Linux OS with the Xenomai preemp-

tive real-time kernel which runs a single real-time applica-tion to handle tasks of different priorities [3].

In order to better manage the controller in an operationalcondition with different motion system applications, we im-plemented a generic Power PMAC project independentlyof the application system which is organized in 3 layers:

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an embedded software layer for Tango axis control inter-face, a subroutines layer for functional sub-programs, and ahardware layer for low-level configurations (see Figure 2).

Embedded software layer: interface for Tango axiscontrol For physical- or virtual- axis control: all com-mands, property settings, attribute reading/writing, andstate/status requests from the Tango software go throughthe embedded software layer to access the firmware. Viapredefined indexed data structures in the shared memory ofthe controller, this layer acts as an intermediate between theTango software and Power PMAC firmware. Data structuresare shown in Figure 4.

Figure 4: Predefined indexed data structures in Power PMACshared memory for Tango axis control.The features of this layer are:– Interpretation of commands provided by the Tango de-vice and that they only run if operating conditions allow.

– Attribute data updating: for exchanging high-level at-tributes with low-level parameters, parameters beingchanged only within allowed conditions.

– Error handling: setting flags in the state/status variableswhen certain errors/warnings occur.

These features are realized by 3 different tasks running in2 threads with separately adjustable cycle times. One singlethread is used for the tasks of interpretation and error han-dling. In the scope of the high-level polling frequency, thisthread has higher priority than the thread used for updatingdata attributes.

Subroutines layer: functional sub-programs defini-tion This layer implements some sub-programs that can becalled or stopped by the software layer command request toperform a processing function or trajectory followed moves.These programs can directly use firmware functions and acton low-level hardware settings. Their execution status arecontinuously checked on by the interface layer for safetyhandling.

Some application-dedicated programs, including motion-and PLC- programs, will be defined and implemented de-pending on the needs. Some common programs will be partof the generic project:– Motion programs for reference-position initialization.

– Duty cycle PLC program for motor stops within a cer-tain period.

– Vacuum mode PLC program to itch motor current de-pending on the motor status (moving or stopped).

– System start-up PLC program to initialize the amplifierand reset the embedded system.

Hardware layer: low-level configurations Some typi-cal hardware setups need to be standardized to minimize andsimplify installation work. These setups have been identifiedof which the configuration files have been templated:

• Encoder conversion setups: Quadrature, Sin/Cos, SSI,BiSS-C...

• Motor setups:– 2-Phase stepper motor setup: closed Loop &

micro-stepping– Motor setup using third-party drives with PFM

signals output– 3-Phase brushless servomotor setup– DC brush motor setup

Based on the tested and validated templates, a GUI tool(see Figure 5) has been developed to automatically gener-ate configuration files according to preselected parameters:channel number, motor type, encoder type, motor currentetc. Hardware commissioning will however require a tun-ing process followed by manual modifications of the files.The PID regulation can be done using the Power PMACIDE tuning tool. From then, the CS (Coordinated System)

Figure 5: Hardware configuration file generator tool.

configurations will be added in the files to create the rela-tionship between controlled axes and motors (see low-levelconfigurations part in Figure 2). To properly benefit fromthe "Power PMAC CS" functionality, an individual motoris associated to a CS for physical axis controls, same as forvirtual axis controls. Each CS configuration is made by aset of Kinematic forward & inverse routines.

A step-by-step procedure on low-level installation config-urations and files archiving procedures for maintenance willbe defined.

Integration Test ResultsUnitary tests of the standardized software and hardware

have been realized and validated. The integration test in theSOLEIL control system is validated with the Power BrickLV in a laboratory setting. Some details need to be finalized.Several low-level tests have been accomplished or are

ongoing on some beamline applications: DCM (double

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crystal monochromator) on PLEIADES, DCM on SAMBA,NANOPROBE (joint project between Synchrotron SOLEILin France and MAXIV in Sweden) [4]. The integration testsare also scheduled for these Beta-tester applications.

SAMBA beamline DCM control upgrade (see Fig. 6)Currently the system is controlled by the CLASSIC solu-tion. This upgrade aims to achieve a low-level direct energycontrol and thereafter a continuous energy-scan operation,which is expected to significantly reduce the experimentduration with faster execution and reduced Ethernet commu-nication.

Figure 6: SAMBA beamline DCM motion system.

The control of the 7 main axes (Rx , Ts2, Tz2, C1, C2, Rz2,Rs2) have been installed on a Power Brick unit. It includesa DC brush and 6 steppers for which the low-level settingshave been tested and validated. The kinematic equationshave also been implemented to provide direct energy control,detailed as following.Equation between E and the main axis Rx (◦) is shown

as below, in which E is the photon energy in eV, d is thelattice spacing in Å, θ is the angle of the main axis of themonochromator Rx in ◦.

E = hc1λ=

hc2d

1sin(θ)

(1)

The remaining motors need to be synchronized with themain axis to obtain the desired energy.

Ts2 and Tz2 are the two translations of the second crystal:

Ts2 = max(TMins2 ,

H2 sin(θ)

); Tz2 =H

2 cos(θ)(2)

C1 andC2 are the positions of the twomotors of the secondcrystal bender. As shown in the equations below, R is theradius of the crystal obtained; 1

R is the curvature. Ai, j arecoefficients:

C1(1R

) = A1,0 + A1,11R

; C2(1R

) = A2,0 + A2,11R

(3a)

1R=

12 sin(θ)

(1p+

1q

) (3b)

Rz2 and Rs2 follow empirical correction curves. Shownin the equations below, p and q are the source to monochro-mator and monochromator to sample distances.

Rs2 = Pn(θ, cRs2 ); Rz2 = Pn(θ, cRz2 ) (4a)

pn(θ, c) =n∑i=0

ciθi c =*...,

c0c1...

+///-

(4b)

Tests in low-level with the kinematic conversions havebeen done and integration tests with the Tango devices willbe done soon. The additional functions of enabling or dis-abling one of the relations for test or to perform a scan, willbe realized with the Tango Device "AppliParameter".

New Complementary ProductTo meet the required applications when external drivers

are in use, a new complimentary product Delta Tau PowerBrick controller is now specified. It contains the same CPU(Power PMAC) as Power Brick LV without the built-in am-plifier, providing PFM and analog signals for third-partydrives. In addition, this product should be fully compatiblewith the CLASSIC controller in respect to cabling connec-tivity; an eventual control upgrade would be fairly direct andeasy.

The same tool settings as well as skill-sets would be usedto configure the new controller. It is expected to be integratedin the SOLEIL control system without extra development.

CONCLUSIONThe new strategy of moving from a model with a single

universal motion controller to a model with two special-ized controllers is being implemented. Operational conti-nuity is ensured with the new CLASSIC controller while atthe same time improving some functionalities. The chosenHIGH PERFORMANCE controller, Delta Tau Power Brick,is very powerful and versatile which allows it to handle highperformance systems.

The main challenge with this controller is to offer the high-performance of the Power Brick and the DMC-4183 to theend user while still keeping an easy-to-use interface. Bothcontrollers are now ready to be used for simple functionali-ties and the next step will be to train the electronic group tohave the necessary skill-sets to maintain these products inoperation. Advanced functions, such as compensation tablesand remote managing of motion programs, will be improved.The HIGH PERFOMANCE controller will bring value todifferent control upgrade applications in projects such asmonochromator, Flyscan, Nanoprobe and Goniometer.

REFERENCES[1] D.Corruble et al., "Revolution in Motion Control at Soleil:

How to Balance Performance and Cost", MOPPC013, Proc. ofICALEPCS’2013, San Francisco, CA, USA (2013)

[2] Observatory-Sciences, Delta Tau Power PMAC Communica-tions Library Manual, Issue 1.2, Dated March 17, 2015

[3] Power PMAC User’s Manual, Delta Tau Document 050-PRPMAC-0U0, Dated Jan 6, 2015

[4] C. Engblom et al., "High Stability and Precision Position-ing: Challenges to Control and Innovative Scanning X-RayNanoprobe", Proc. of ICALEPCS’2015, Melbourne, Australia(2015)

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