in-orbit demonstration of rendezvous laser radar for unmanned autonomous rendezvous docking

In-Orbit Demonstration ofRendezvous Laser Radar forUnmanned AutonomousRendezvous Docking

MASAAKI MOKUNO

ISAO KAWANO

TAKASHI SUZUKIJapan Aerospace Exploration Agency (JAXA)

The National Space Development Agency of Japan (NASDA)

performed unmanned autonomous rendezvous docking (RVD)

experiments using the Engineering Test Satellite VII (ETS-VII)

in 1998 and 1999. In these experiments, a rendezvous laser

radar (RVR) was used as the primary navigation sensor during

the final approach phase (relative distances from 500 m to

2 m). The RVR functioned properly, and its characteristics,

which are measurement accuracy, optical propagation, and

acquisition/tracking, satisfied the requirements. The experimental

results show that RVR is effective for autonomous rendezvous

docking.

Manuscript received May 7, 2003; revised September 12, 2003;released for publication December 16, 2003.

IEEE Log No. T-AES/40/2/831380.

Refereeing of this contribution was handled by E. S. Chornoboy.

Formerly the National Space Development Agency of Japan.

Authors’ address: Satellite Applications Center, Office of SpaceApplications, JAXA, 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505,Japan.

0018-9251/04/$17.00 c 2004 IEEE

INTRODUCTION

Rendezvous docking (RVD) is indispensablefor space activity. To conduct autonomous RVD,navigation is as important as guidance and control.Many recent RVD flights have been conducted bymanned spacecrafts, where an astronaut pilots theirspacecraft using navigation. Currently, Russianspacecrafts conduct automatic RVD, but in the future,both manned and unmanned RVD will become amore prevalent space activity. The European SpaceAgency (ESA) and the National Space DevelopmentAgency of Japan (NASDA) are currently developingunmanned orbit transfer vehicles to supply materialsto the International Space Station (ISS) [1, 2].Furthermore, future Mars explorers attempting toreturn samples from Mars will need to conductunmanned RVD in Mars orbit [3].

In 1997, NASDA launched the Engineering TestSatellite VII (ETS-VII) to demonstrate unmannedautonomous RVD in orbit. The ETS-VII is uniquein that it consists of two satellites: “Chaser” and“Target” (Fig. 1). After injecting in orbit, Chaserundocks from Target and conducts RVD experiments.In 1998 and 1999, NASDA successfully performedunmanned autonomous RVD three times [4, 5].In these experiments, Chaser made flights up tomaximum range of 12 km from Target and dockedagain. The ETS-VII has three navigation systems:GPS relative navigation, RendezVous laser Radar(RVR), and proximity camera sensor (PXS); and theETS-VII switches among these systems according torelative distance. The RVR was used as the primarynavigation sensor for relative distances from 500 mto 2 m.

Fig. 1. Engineering test satellite VII.

The RVR laser radar uses a near-infrared laserdiode (LD) and radiates pulsed light (wavelength810 nm) from Chaser in an 8.5 deg cone. The laserlight is reflected by Corner Cube Reflectors (CCRs)on Target and returns to Chaser. The RVR detectsthe reflected light using a charge coupled device(CCD) camera and an avalanche photo diode (APD).The RVR estimates the line-of-sight (LOS) angle by

IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS VOL. 40, NO. 2 APRIL 2004 617

Fig. 2. Docking planes of chase and target satellite.

processing the CCD image and computes the relativerange by comparing the phase difference betweentransmitted and received beam.Rendezvous radars have been developed and

operated by both Russia and the United States.Russian spacecrafts, such as Soyuz and Progress, havethe KURS system [6] to conduct automatic RVD.The KURS system has been operated since 1985,employs an RF radar using S-band, and is able tomeasure relative position, velocity, LOS angle, LOSangle rate, etc. Its measurement range is wide (from10 km to docking), but its measurement accuracy islower than that of laser radar. Regarding laser radar,NASA has developed the trajectory control sensor(TCS) [7] for the US Space Transportation System(STS). The TCS is an optical laser radar and is ableto measure relative position, velocity, and LOS anglefrom 1.5 km to 1.5 m. But TCS is only used as acrew aid for manual RVD. Our RVR is different fromthese sensors because it has been integrated into theclosed-loop control system enabling high accuracy andautonomous RVD.In the work presented here, we describe the

ETS-VII RVD system and the final approach phaseof the rendezvous scenario using RVR. We alsopresent an overview of the RVR design and discussmajor experimental results such as measurementaccuracy, optical performance, and acquisition/trackingperformance in the RVD experiments.

EXPERIMENTAL SYSTEM

The ETS-VII is an in-orbit demonstration andtest satellite for RVD and space robotics technology.It consists of two satellites: Chaser and Target. TheETS-VII satellite mass is 2900 kg including the TargetSatellite mass of 400 kg. The box size of Chaser isabout 2.6 m long, 2.3 m wide, and 2 m tall. The totalwidth of Chaser, including two solar panels, is about20 m. Target is 0.65 m long, 1.7 m wide, and 1.5 m

Fig. 3. Block diagram of ETS-VII RVD system.

tall, and has a 6.6 m long rigid solar panel. The RVDequipment (such as the navigation sensors, reflectors,and docking mechanisms) are installed on the dockingplane of each satellite (Fig. 2). Fig. 3 shows a blockdiagram of the ETS-VII RVD on-board system.Autonomous RVD is managed by a guidance controlcomputer (GCC) installed on Chaser. The GCCincludes on-board flight software, and conducts bothattitude and orbit control during RVD experiments. Inaddition, the GCC has a flight management functionfor mode control, fault tolerance, etc. The flightmanagement function realizes autonomous RVD.The ETS-VII has three navigation systems to ensureunmanned autonomous RVD. The first is PXS, whichis used from 2 m to docking (docking approachphase). The second is RVR, which is used from500 m to 2 m (final approach phase). The third isGPS relative navigation, which is used from 9 kmto 500 m (relative approach phase). Both Chaser andTarget have GPS receivers (GPSR). For GPS-relativenavigation, Target’s GPSR data are sent to Chaser’sGPSR via Chaser-Target communications link. ThenChaser’s GPSR processes the data measured byboth satellites’ GPSR data and estimates its relativeposition and velocity to Target using extended Kalman

618 IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS VOL. 40, NO. 2 APRIL 2004

Fig. 4. Acquisition condition of RVR at TF point.

filter (EKF). Chaser estimates the relative positionand velocity every 10 s. The GCC switches amongthese navigation systems depending on relativerange. An Earth sensor assembly (ESA) and InertialReference Unit (IRU) are installed to acquire attitudeand attitude rate. The 20N thrusters are used asactuators for Chaser. Experimental operations wereconducted from Tsukuba Space Center (TKSC) via atracking and data relay satellite (TDRS). In the RVDexperiments, Chaser detached the Target satellite andmade rendezvous flights up to 12 km.The RVR is used as the primary sensor in the

final approach phase and is able to measure bothrelative range and LOS angle. Chaser is injected to itsterminal phase finalization (TF) point by using GPSrelative navigation. Chaser changes its attitude basedon GPS relative navigation and the RVR acquiresTarget in the measurement area. After that, Chaserswitches its navigation from GPS relative to RVR.Then Chaser approaches Target along the V-bar. Fig. 4shows the injection area around the TF point. Therelative GPS navigation error and injection error atthe TF point are estimated to be 20 m and 80 m,respectively. Accordingly, RVR must support a fieldof view (FOV) given by

Fig. 5. Overview of final approach phase.

FOV = tan 1(20 m(= Relative GPS navigation error)=(RTF-TF injection error)) (1)

where, RTF is the distance from Target to the TFpoint. Note, distance RTF is restricted by applicablelaser power. Therefore, the TF point is set up at520 m and the FOV of the RVR is 3 deg, and theRVR measurement range is 600 m. Fig. 5 showsan overview of the final approach phase, whereChaser estimates relative position and velocity usingRVR navigation. Chaser then issues orbiting controlcommands using a reference-trajectory guidance law.The reference trajectory is set up along the V-bar(V-bar approach). During V-bar approach, Chaserexecutes LOS pointing control against Target usingRVR navigation. Chaser approaches Target at thespeed of 5–10 cm/s. At the end of the final approachphase, Chaser is injected to vicinity point (VP) at adistance of 2 m. At the VP point, Chaser changesits navigation to PXS. The requirements of injectionaccuracy are less than 0.3 m in position and 0.01 m/sin velocity.

RENDEZVOUS LASER RADAR

The RVR laser radar uses a near-infrared LD andcan measure out to a relative range of 660 m andwithin an LOS angle of 4 deg. The unique feature ofthe RVR is its laser transmission method: it expandsits laser beam in the specified angle and has noscanning system such as TCS. We call it “static-type”laser radar. The static-type laser radar has followingadvantages. First of all, reliability is high because itsmechanism is simple. Subsequently, ground testingis easy with a static-type laser radar. Finally, over allcost is reduced. This design concept was establishedduring the research phase [8].

MOKUNO ET AL.: IN-ORBIT DEMONSTRATION OF RENDEZVOUS LASER RADAR 619

Fig. 6. Photo and schematic diagram of RVR.

The RVR consists of three subcomponents:RVR-head (RVR-H), RVR-electronics (RVR-E), andRVR-reflector (RVR-R) (Fig. 6). Fig. 6 also showsa schematic diagram for RVR, and Table I lists itsspecifications.The ETS-VII has two sets of RVR, which are

called “main” and “sub.” Two of RVR-H and RVR-Eare installed on Chaser; two of RVR-R-1 and oneof RVR-R-2 are installed on Target. RVR-R-2 iscommonly used for measurement by both two ofRVR-H illustrated in Fig. 2.The RVR-H contains both laser transmitting

and receiving functions. It radiates near infrared(wavelength: 810 nm) to an extent of 8.5 deg coneusing an laser diode LD. This laser beam is modulatedover 15 MHz/14.55 MHz for range measurement.The RVR-H receives the reflected light from theCCR array (RVR-R) installed on Target. The receivedbeam is divided by a half mirror to send to thetwo-dimensional CCD and APD. The CCD detects thetwo dimensional position of the reflected beam andthe APD measures optical power. These data are sentto the RVR-E.The RVR-E contains the calculation, control, and

telemetry/command functions. It calculates relativerange and LOS angle using the APD and CCD data.Regarding relative range, RVR-E compares the phasedifference between the transmitted and received

TABLE ISpecifications of RVR

Item Specification

Emission Laser DiodeDevice Wavelength: 810 nm+= 3 nm @Tc = 20 C

Output: 50 mW

Receiver Range measurement: Avalanche Photo Diode(APD)

Device LOS angle measurement: Two dimensional CCD

Acquisition/ Relative range: 0.3 m–660 mMeasurement Field of View: Range measurement: 3 deg in half

corn angleCondition LOS measurement: 4 deg in half corn angle

Relative attitude angle: 15 deg maxRelative speed: 1.0 m/sLOS angle rate: 0.5 deg/s

Acquisition/ Acquisition time: 12 sMeasurement Measurement rate: 0.5 sPerformance Output delay time: 0.5 s

Range measurement accuracy:Bias (0-P): Max(0.1, 0.001 R)(m)Random (3¾): Max(0.006, 0.0034 R0:65)(m)

LOS angle measurement accuracy:Bias (0-P): 0.05 degRandom (3¾): 0.02 deg


beams. Because RVR would have an ambiguity of10 m using only the 15 MHz beam, two frequencymeasurements (15 MHz and 14.55 MHz) are usedto resolve ambiguity at acquisition. Although thistwo-frequency measurement still results in a 333 mambiguity, this can be detected by measuring theoptical power of the reflected beam. Regarding LOSangle, RVR-E processes the images taken by the CCDusing image-processing methods. The RVR takestwo images of LD ON and LD OFF, and RVR-Esubtracts the LD-OFF image from the LD-ON imageto eliminate the optical disturbance. The RVR thenprocesses the difference image using image processingmethods such as labeling and grouping. Finally,RVR-E outputs the relative range and (X,Y) positionon the CCD of the reflected beam. The RVR-E sendsthese data to the GCC via an RS-422 connection. Themeasurement rate of the RVR is 2 Hz.The RVR-R consists of two types of reflectors.

One is RVR-R-1, which is used for far-rangemeasurement. The other is RVR-R-2, which is usedfor near-range measurement. Reflector RVR-R-1 hasa 24 corner cube array with each CCR’s edge size5 cm and it is used commonly for both main and subcomponents of RVR-H. Reflector RVR-R-2 has oneCCR and its edge size is 2 cm. Two sets of RVR-R-2are installed on Target.The RVR can function under the optical

interference of the Sun and other active opticalsensors. When reflected or direct sunlight injectsstrongly into RVR-H, the interference detector (APD)illustrated in Fig. 6 detects the interference level andthen a neutral density (ND) filter is automaticallyinserted by an insert mechanism, which is like themechanism for the waveguide switch, to reduce thesunlight interference. If the ND filter is insertedunder the reflected sunlight interference, the RVRcan keep measuring within the relative distance of40 m. Regarding the direct sunlight interference, sinceit is difficult to eliminate it perfectly, we avoid thedirect sun light interference by adjusting rendezvousapproach timing. Additionally, RVR-H has a bandpassfilter (BPF) with bandwidth of 30 nm to avoidinterference caused by PXS with a wavelength of640 nm.

EXPERIMENT RESULTS AND DISCUSSION

Rendezvous Flight using RVR

NASDA executed the ETS-VII RVD experimentsthree times. The first occurred in July 1998. In thisexperiment, Chaser performed the separation anddocking flight within a relative distance of 2 m.Chaser performed 6 deg of freedom control usingPXS during the rendezvous flight, and we couldacquire the RVR data in the near range. In thesecond and third RVD experiments, Chaser flew to amaximum range of 12 km and performed autonomousRVD using not only the PXS navigation but also

Fig. 7. RVR navigation result in final approach phase (3rd RVDexperiment). (a) RVR acquisition and V-bar approach.

(b) Injection to VP point (X = 2 m). Telemetry data was notacquired between 11:13:00 to 11:15:40 because of downloading

stored data from Chaser.

the RVR and GPS-relative navigation. Fig. 7 showsthe RVR flight data of the final approach phase forthe third experiment. Chaser switched its navigationfrom GPS relative to RVR at 220 m. Chaser thenapproached Target at a velocity of 5–10 cm/s alongthe V-bar. The RVR navigation data correspond to thecommand data issued by the GCC. Injection accuracyat the VP point is better than the requirements. ThusRVR worked properly in the closed-loop control.

Measurement Accuracy

The RVR measurement accuracies are verified bycomparison with the other navigation sensors, whichare PXS and GPS-relative navigation, as well as allground-test data.

Before starting the RVD experiments, the RVRmeasurement accuracy was checked under the dockingcondition. Table II shows the results of this operation.The requirements for bias error are 10 cm in rangeand 0.05 deg in LOS angle as shown in Table I. Therange differences between in-orbit data and grounddata are within 2 cm. The LOS angle differences arewithin 0.05 deg except for El of the sub component.


TABLE IIRVR Measurement Accuracy Under Docking Condition

(a) Bias Error

In-Orbit Data Ground Test Data Difference

Sub Main Sub Main Sub Main Spec.

Range (m) 0.47768 0.47752 0.49500 0.48124 0.01732 0.00372 0.1

LOS (deg) El 0.07281 0.03600 0.02123 0.00909 0:05158 0:02691 0.05Az 0:02527 0:13428 0:05055 0:13144 0:02528 0.00284 0.05

The range was 0.4806 m measured before launching ETS-VII.

(b) Random Error (3 sigma)

In-Orbit Data Spec.

Range (m) 0.004554 0.006

LOS (deg) El 0.004332 0.02Az 0.008361 0.02

Fig. 8. Range measurement result by RVR and PXS.

These differences include vibration, thermal strain,and other effects induced by launch environments.Accordingly, actual measurement accuracies are moreprecise than these results. The random errors of RVRare better than the requirements of 0.006 m (range)and 0.02 deg (Az, El).To evaluate the near-range characteristics of RVR,

we compare the RVR data with the PXS data. Inthe first experiment, Chaser made a flight up to 2 mfrom Target. Initially, Chaser departed from Target.Then Chaser maintained a relative position near2 m for 15 min. After that, Chaser approached anddocked with Target again. During the experiment,we acquired both RVR and PXS data simultaneously.Fig. 8 compares the range data as measured by RVRand PXS. Since the position difference between thePXS and RVR is 5 cm and the measured differenceis about 12 cm during the maneuver, the resultingaverage difference is 7 cm. Here, the specific rangebias error of PXS is less than 5 mm within the relative

distance of 2 m. Therefore the range bias error ofRVR is better than the requirement of 10 cm. Fig. 9shows the LOS angle measured by both sensors whenChaser kept the position at a range of 2 m. The biaserrors of RVR are 0.09 deg in Az and 0.12 deg in El.These errors are larger than the check-out data shownin Table II. We presume these changes are caused bythe following reason. The PXS measures the position(X,Y,Z) and attitude (roll, pitch, yaw) of Chaser’sdocking frame against Target’s docking frame. In thedocking phase, Chaser controls the relative positionand attitude to align both docking axes by using PXSnavigation. But RVR is installed Y = 0:715 m andZ = 0:355 m away from the docking axis. Besides,RVR measures the LOS angle with respect to Chaser’sdocking frame. Therefore the relative attitude errorsmake the LOS angle difference between the PXSand RVR become large. This difference cannot beestimated by means of PXS because its relativeattitude accuracy is 0.5 deg. Anyway, it must be notedthat RVR LOS accuracy is better than 0.12 deg in nearrange.

To evaluate the far range characteristicsof RVR, we compared the RVR data with theGPS-relative navigation data. In the second andthird experiments, both navigation data sets wereacquired simultaneously at the handover point fromthe relative-approach phase to the final-approachphase. The GPS-relative navigation outputs relativeposition (X,Y,Z) and velocity with respect to theHILL coordinate frame. To compare with RVRnavigation, we calculate the GPS-relative navigationdata listing the equation. Az = tan 1(Y=X). El =tan 1(Z=X). R = SQRT(X2 +Y2 +Z2). Fig. 10shows the difference between the RVR navigationand GPS-relative navigation at the 520 m point. Sincethe data update period of the GPS relative navigationis 10 s, the RVR data and GPS relative navigation


Fig. 9. LOS angle measurement result by RVR and PXS.

data are compared every 10 s. During this period,Chaser maintained a position near 520 m using RVRnavigation. The mean difference between the twonavigation systems is 0.88 m. On the other hand, theLOS angle differences between the two navigationsystems are less than 0.1 deg. The measurementaccuracies of the GPS-relative navigation of ETS-VIIis 0.7 m as Y-axis and 2 m as Z-axis, respectively[9]. These values correspond to 0.08 deg in Az and0.22 deg in El at a relative distance of 520 m. Inthe case of far range, although we cannot evaluatewhether the RVR navigation accuracy is less than itsspecification or not, the RVR navigation had sufficientaccuracy to conduct autonomous RVD.

Optical Performance

It is important for RVR to ensure an optical linkduring measurement because it is a static-type laserradar and spreads its laser beam in the area of 8.5 deg

Fig. 10. Range measurement result by RVR and GPS relativenavigation.

cone angle. Generally, the receiving power reducesin proportion to the forth power of the measurementrange. Additionally, in the far range, the diameterof the CCR, which is derived from area of effective


Fig. 11. Definition of CCR arrangement.

reflecting area of CCR, becomes much smaller thanthe relative range. This situation induces the wellknown Fraunhofer diffraction, which reduce receivedpower further.Fig. 11 illustrates the CCR arrangement. We

assume that the RVR’s laser has a Gaussian beamwith spread angle 8.5 deg (= 2 µt). The towardoptical loss (Lt) at the CCR is

Lt =2

¼µt2R2exp

2µc2

µt2Ac Nc (2)

where µc is the angle between optical axis and thedirection of CCR, Nc is the number of CCR and Acis the effective reflecting area of the CCR.After reflection by the CCR, the beam propagates

geometrically with a divergence angle and propagatesto the RVR. Accordingly, the received beam area istwice that of the reflecting area at the CCR position.Therefore the outward optical loss is given by

Lo=rR

µCR R

2rR2rC

2

, rR < 2rc (3)

where rR is the radius of the receiving optics, rC isthe radius of the CCR reflecting area, and µCR is thedivergence angle of the reflected light at the CCR.In far range, the received beam is spread more due

to Fraunhofer diffraction. This effect increases theoutward optical loss. In our case, this effect decreasethe optical power by about 1–2 dB at a relative rangeof 600 m. The total optical loss includes additionalloss such as the transmitter optical loss (Ltr), CCRloss (Lc) and receiver optical loss (Lrc). Therefore, thetotal optical loss is shown as

L= Lt Lo Ltr Lc Lrc: (4)

In the in-orbit experiments, the RVR measured opticalpower in the measurement area. The optical powerwas acquired using an APD installed on the RVR-H.Fig. 12 shows the relation between RVR optical powerand relative range. This graph includes the in-orbitexperiment data, ground data, and analysis data. Wehave selected those in-orbit experiment data whoseLOS angle is less than 0.1 deg and the analysis datawere calculated based on formulas (1)–(4). In this

Fig. 12. RVR optical power versus relative range.

Fig. 13. RVR optical power versus LOS angle.

figure, the analysis data correspond with the orbit datain far range. On the other hand, the ground data areless than the orbit data. The reason for this differenceis that atmospheric turbulence reduces the opticalpower in the ground test. Fig. 13 shows the relationbetween the RVR optical power and LOS angle. In thefinal approach phase, Chaser conducts acquisition ofTarget within 3 deg as LOS angle. After that, Chaserautomatically controls the LOS angle down to 0 deg.In this figure, the optical power increases accordingto the change of LOS angle. The change value isabout 1.5 dB, similar to 1.9 dB calculated using theformula (2). These results show that the level ofoptical propagation of the RVR is good enough tooperate in the required measurement area.

Throughout the RVD experiments, there was nosunlight interference or inter-sensor interference inthe RVR. Accordingly, the RVR functioned properlyunder the in-orbit optical environments.

Acquisition and Tracking Function

The RVR conducted acquisitions of Target at thedocking positon and handover point from GPS-relativenavigation. At the 500 m and 150 m holding points,the RVR could acquire Target properly. At thedocking point, the acquisition times are less than 12 sas designed.


CONCLUSIONS

The RVR, which is a rendezvous laser radar forautonomous RVD, was developed and demonstratedin orbit. The RVR is a static-type laser radar withoutscanning mechanism and is able to measure relativeposition within 660 m and a LOS angle within ahalf cone angle of 4 deg. The ETS-VII successfullyperformed autonomous rendezvous using the RVRin the final approach phase at relative distances from500 m to 2 m. Chaser was navigated using the RVRand injected to the VP point (relative distance is 2 m)with accuracy better than requirements. The RVR’smeasurement accuracies (bias error) in near range areless than 10 cm in relative range and about 0.1 deg inLOS angle. In far range, the RVR has measurementaccuracies (bias error) that are less than 1 m inrelative range and 0.1 deg in LOS angle. Opticalperformance of the RVR, which is the importantproperty for the laser radar, was also evaluated.Optical propagation corresponds to that estimatedbefore launch. During the RVD experiments, opticalinterference did not occur and acquisition/trackingworked properly. These experimental results show thatrendezvous laser radars, such as RVR, are effective forunmanned autonomous RVD.

REFERENCES

[1] Heloret, J-Y., and Laine, R. (2002)Overview of the development of the European automatedtransfer vehicle.In Proceedings of the 53rd Internatinal AstronauticalCongress The World Space Congress—2002, Oct. 2002,IAC-02-T.P.03.

[2] Kawasaki, O., Yamanaka, K., Imada, T., and Tanaka, T.(2000)

The on-orbit demonstration and operations plan of theH-II transfer vehicle (HTV).In Proceedings of the 51st International AstronauticalCongress, Oct. 2000, IAF-00-T.2.08.

[3] Sherwood, B. (2002)Mars sample return: Architecture and mission design.In Proceedings of the 53rd Internatinal AstronauticalCongress The World Space Congress—2002, Oct. 2002,IAC-02-Q.3.1.08.

[4] Kawano, I., Mokuno, M., Kasai, T., and Suzuki, T. (2001)Result of autonomous rendezvous docking experiment ofEngineering Test Satellite-VII.Journal of Spacecraft and Rocket, 38, 1 (Jan.–Feb. 2001),105–111.

[5] Kawano, I., Mokuno, M., Kasai, T., Yamanaka, K., Koyama,H., and Suzuki, T. (2002)

Achievement of rendezvous docking trials throughoperation of the Engineering Test Satellite-VII.In Proceedings of the 23rd International Symposium onSpace and Technology and Science (ISTS), June 2002,ISTS 2002-d-32.

[6] Suslennikov, V. (1993)Radio system for automatic rendezvous and docking ofSoyuz, Progress spacecraft and MIR space station.In Proceedings of the Third European In-orbit OperationTechnology Symposium, Noordwijk, June 1993, 101–106.

[7] Polite, M. (1998)An assessment of the technology of automatedrendezvous and capture in space.Technical Report NASA-TP-1998-208528, NASA, 1998.

[8] Anegawa, H., Wakabayashi, Y., Shimizu, M., Nagai, M.,Yasugi, T., and Shiratama, K. (1989)

Tracking laser radar for rendezvous docking: Aconceptual design.In Proceedings of the AIAA Guidance, Navigation, andControl Conference, 1989, 1590–1597.

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Masaaki Mokuno received a Master of Engineering from Osaka University in1990. Since 1990, he has worked for the National Space Development Agencyof Japan (NASDA) and Japan Aerospace Exploration Agency (JAXA). In 1992,he joined the Engineering Test Satellite VII (ETS-VII) project and was involvedin developing the unmanned autonomous rendezvous docking system andrendezvous navigation sensors. He was involved with the ETS-VII experiments.Mr. Mokuno was awarded the Tomoda Award from the Society of Instrument

and Control Engineers of Japan in 1999. He is a member of the Japan society forAeronautical and Space Science and the American Institute of Aeronautics andAstronautics.

Isao Kawano received an M.S. in astronautical engineering from the Universityof Tokyo. Since 1986, he has worked for the National Space DevelopmentAgency of Japan (NASDA) and Japan Aerospace Exploration Agency (JAXA).His research interest covers space vehicle navigation using Global PositioningSystem (GPS), autonomous rendezvous docking system, and rendezvousnavigation sensors. He was the principal investigator and conductor of theETS-VII rendezvous docking experiment.Mr. Kawano won the Technical Award (Tomoda Award) from the Society of

Instrument and Control Engineers of Japan in 1999. he is a member of JapanSociety for Aeronautical and Space Science, the Society of Instrument andControl Engineers of Japan.

Takashi Suzuki received a Bachelor of control engineering degree from theTokyo Institute of Technology. Since 1982, he has worked for the National SpaceDevelopment Agency of Japan (NASDA) and Japan Aerospace ExplorationAgency (JAXA). He was the project manager of the autonomous rendezvousdocking experiments of ETS-VII in 1998 and 1999. Currently he is working inthe Cabinet Satellite Intelligence Center.


in-orbit demonstration of rendezvous laser radar for unmanned autonomous rendezvous docking

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