Proceeding of the 6th International Symposium on Artificial Intelligence and Robotics & Automation in Space: i-SAIRAS 2001, Canadian Space Agency, St-Hubert, Quebec, Canada, June 18-22, 2001.
Flight 6A: Deployment and Checkout of the Space Station Remote Manipulator System (SSRMS)
Rod McGregor1 and Layi Oshinowo2
Canadian Space Agency 6767 Route de l’Aeroport, St-Hubert, Quebec, Canada, J3Y 8Y9 [email protected] [email protected]
Keywords Activation, Canadarm2, Checkout, Deployment, Flight 6A, International Space 1.0 Introduction Station, ISS, Mobile Servicing System, MSS, Space Station Remote Manipulator System, The SSRMS was built for the Canadian Space SSRMS, STS-100. Agency (CSA) by MacDonald Dettwiler Space and Advanced Robotics (formerly Spar Abstract Aerospace) located in Brampton, Ontario. The SSRMS, or Canadarm2, is the principal Flight 6A of the International Space Station component of the MSS, Canada’s primary (ISS) assembly sequence, is currently completing hardware contribution to the International Space stage (shuttle departed) operations after its Station program. The Mobile Base System successful docked phase in April of this year. (MBS) and Special Purpose Dexterous This mission marks the delivery and checkout of Manipulator (SPDM) follow later on Flights UF- the first element of the Canadian Mobile 2 and UF-4 respectively. Delivery of the MSS Servicing System (MSS) – the Space Station components has been planned to progressively Remote Manipulator System (SSRMS). The expand the required robotic reach envelope for presence of this seven-jointed, re-locatable, and component installation and servicing, currently functionally-redundant robotic manipulator on- at the limit of the SRMS. orbit, with it’s larger reach and mass-handling The Canadarm2 was delivered to the ISS by the capacity, will allow for the expansion of the Space Shuttle Endeavor during the recently Station towards its assembly-complete form; completed Flight 6A mission. This paper is an beyond that which would be possible using only immediate post flight accounting of the primary the Shuttle Remote Manipulator System (SRMS) mission objectives of activation and checkout of a.k.a. the “Canadarm”. the SSRMS during docked operations. These In the immediate aftermath of the flight, the activities are described in four Phases. In Phase focus of this paper is to account the success of 1, initial activation required an initial EVA to the primary mission objectives of deployment route power and data cables to the Launch and checkout of the SSRMS. Operations are Deployment Assembly (LDA); the SSRMS described from removal of the folded SSRMS folded into a Space Lab Pallet (SLP), launch package from Space Shuttle Endeavor’s temporarily installed on the US Laboratory payload bay to it’s fully deployed configuration Module (US Lab) by the SRMS. In Phase 2 at the end of the docked (shuttle present) phase operations, commanded by the ISS crew from a of Flight 6A operations. Also discussed in the Robotic Workstation (RWS) in the US Lab, the paper are, from the SSRMS perspective, the SSRMS was maneuvered through a ‘step-off’ various extra-vehicular activity (EVA) and extra- sequence from the SLP to grapple the US Lab vehicular robotic (EVR) tasks executed to Power Data Grapple Fixture (PDGF) with it’s achieve these objectives, some of the mission Latching End Effector (LEE). For Phase 3, a constraints, and the operational processes and second EVA was performed to configure power products that are required for the success of and data connections to the US Lab PDGF, Flight 6A. which will serve at the SSRMS base for operations until the delivery of the MBS in early 2002. Finally, in a fourth Phase, the SLP was maneuvered by the SSRMS to a handoff position
1 Flight 6A Backup Lead, Space Operations Group, Canadian Space Agency (Calian Technologies Ltd). 2 Flight 6A Lead, Space Operations Group, Canadian Space Agency (MD-Robotics Ltd.).
over to the SRMS, for return to the Shuttle 2.2 Launch Deployment Assembly payload bay. Various SSRMS On-orbit Checkout Prior to launch, the SSRMS was folded into a Requirements (OCRs) were integrated into the modified Space Lab Pallet (SLP) called the activation and deployment activities. The OCRs Launch Deployment Assembly (LDA) as shown and their pass/fail criteria were designed with the in Figure 1. The LDA served the following roles; near term objective of demonstrating required • Physical integration into the Orbiter payload functionality for ISS assembly operations bay as in Figure 3. starting with the Airlock installation on Flight • Structural attachment of SSRMS for Launch 7A in June 2001. Loads. • Unberth and installation interface to USLab 2.0 Hardware Description using Shuttle RMS. • EVA worksite. 2.1 The Space Station Remote Manipulator System (SSRMS) Eight, one meter long ‘Superbolts’ attach the SSRMS to the SLP for launch load restraint. The MSS equipment, operational capabilities, LEE A of the SSRMS is connected to an active modes and features have been described Flight Support Equipment Grapple Fixture extensively in the literature throughout its (FSEGF) which will supply power and data to development [1]. The SSRMS is 17 meters in the arm for initial deployment once connected by length, capable of maneuvering payloads up to EVA to the USLab. LEE B, the intended tip for the mass of the Space Shuttle itself. Seven joints initial deploy, is similarly restrained for launch are found on the shoulder and wrist clusters and by a passive (non-powered) FSEGF. The LDA is the mid-span elbow. These provide seven equipped with a Flight Releasable Grapple degrees of freedom, allowing infinite Fixture (FRGF) to allow the Shuttle RMS to configuration possibilities for any given position unberth, maneuver and install the LDA to the of the tip. The arm is symmetrical with two Lab LCA (Lab Cradle Assembly). The LDA has identical LEE’s, each able to serve as tip or base. the passive end of an LCA attachment The SSRMS has two functionally redundant mechanism, which is installed to the active LCA strings (power, data, electronics), allowing on the USLab. The total mass of the continued operations on the opposite string in the LDA/SSRMS assembly is 3050 kg. event of a fatal failure of a component. The Avionics (Arm Computer Unit, Video Distribution Unit) and LEEs, Joints and Cameras, as well as the two booms are all Orbital Replaceable Units (ORU’S) to facilitate on-orbit maintenance. The arm is commanded by the crew through one of two redundant Robotic Workstations, currently assembled in the USLab (Figure 7). The operator can manipulate the SSRMS through pre-programmed trajectories (automodes), or by manual control using translational and rotational handcontrollers. Manual modes can be single- joint operations where each joint is moved individually through a prescribed angle, and Figure 1: SSRMS on SLP, Launch Deploy Manual Augmented Mode (MAM), where the Assembly LEE tip, or any desired Point of Resolution (POR) is effectively ‘flown’ to a destination 2.3 USLab and Grapple Fixtures point through handcontroller input. Motion at the workstation is monitored by the operator (and The ISS USLab will be the base of operations for ground) by telemetry delivered to a Graphical the SSRMS over most of the next year. As of User Interface (GUI), and three monitors for Flight 5A.1, the lab was equipped with two video feeds routed from Orbiter, Station, or the RWS’s for human-in-the-loop command and arm itself. operation of the manipulator (see Figure 7). External to the lab are two grapple fixtures for
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use by each end of the SSRMS. A standard The Checkouts planned for execution on the FRGF is to be captured by the SSRMS Tip LEE flight are listed in Table 1 in priority order with for structural support during long-term stowage. the associated Mandatory or Highly Desirable The Power Data Grapple Fixture (PDGF) has designation. The Mandatory SSRMS checkouts four receptacles which are mated to the Base are the highest 6A mission priority, after LEE Latches for Power/Data/Video connection Docking to ISS and SSRMS Activation / and structural / mechanical interface to the ISS Deployment. Checkout tasks designated as (Figure 2). Highly Desirable and some Desirable (not included with Table 1) are timelined for the mission, however remain subject to deferral in accordance with pre-set constraints. ‘Operational Pass’ criteria were pre-set with consideration to immediate mission objectives of readiness for cargo element manipulation. For this level, functionalities are evaluated against basic Go-no-Go criteria of expected GUI annunciation, and expected system performance as observed by crew and/or ground personnel at the Mission Evaluation Room (MER) in Houston and the Space Operations Support Center (SOSC) at CSA, St-Hubert. All data telemetry is Figure 2: Power Data Grapple Fixture downlinked to service the less immediate checkout objectives of commissioning, performance trending, and component 3.0 On-Orbit Checkout Requirements characterization.
More than 50 individual functionality checkouts 4 SSRMS Activation and Checkout have been established for the SSRMS, with 40 tasks scheduled for 6A docked operations. Each 4.1 Phase 1: EVA Deploy, Powered Static of these tasks serves up to three objectives: Checkout, and Robotic Boom Raise
1. Establish equipment readiness for ISS Following a successful Launch on April 19, 2001 assembly operations (i.e. Flight 7A Airlock the Orbiter docked with the International Space installation) Station at 111/14:11:00 GMT. From the time of 2. Commissioning tests to confirm compliance docking to the ISS, thermal survival limits of to design specification. SSRMS components were limited to 68 hours 3. Data collection for on-orbit characterization without application of Keep Alive (KA) power. or performance trending / degradation monitoring.
Tasks supporting the first objective have been designated as Mandatory checkouts for Flight 6A and Go Criteria for 7A launch.
Mandatory classification for a checkout task is exclusive to the following criteria:
• Required to establish the SSRMS LEE as the operating base on the USLab. • Functionality exercised in performance of payload installation missions between 7A and UF-2. • Redundancy and any other functionality required for SSRMS string failure contingency or ORU replacement. Figure 3: LDA in Endeavor Payload Bay. Aft cargo is Italian MPLM (NASA Photo)
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On the following day (Flight Day 3), the LDA boom in their permanent configuration (see assembly was unberthed from the payload bay Figure 4). and installed to the USLab LCA interface. In Difficulty was encountered seating the fasteners. parallel with the LDA install, EVA 1 preparation Crew advised that the EDFs were approaching activities were underway to facilitate application objective torque in far fewer than expected turns. of heater power to the arm as soon as possible. Subsequent EDF torquing had the effect of CSA Astronaut Chris Hadfield (EV1), and Scott loosening the adjacent fasteners. This was not Parazynski (EV2) egressed the spacecraft at entirely unexpected behavior; the crew had 112/11:55:00 GMT. The ‘IVR’ RWS operator observed this effect during earlier fit checks with commanded safety inhibits to the power feed and flight hardware at MDR Brampton. With this the FSEGF cables from the LDA were attached familiarity, and advise from MDR personnel in by the EVA crew. Keep Alive power was Houston, multiple torquing sequences were commanded to the SSRMS from the ground at applied, and the torque was increased from 25 to 112/13:21 (24 hours into the 68 hour constraint), 30 ft/lbs until tightness of all fasteners was with telemetry confirming successful application. assured An MCC Go was then provided for Superbolt release. This action breaks the structural load path and would preclude a return to ground contingency in the event of failure to apply power to the arm. The EVA crew proceeded with other tasks to allow time for SSRMS to reach sufficient temperature for a safe transition to Operational. At 112/14:58, the folded SSRMS booms were raised to 34.5 degrees by EV2 (Parazynski) to provide clearance for EDF insertion to the boom hinge. This was a manual operation performed by EV2 in a ‘clean and jerk’ style maneuver. Practiced in the Neutral Buoyancy Lab for a 70 lb load application, this task proved to require double this force to induce the required Figure 5: SLP installed on USLab, backdriving of the joints. SSRMS booms unfolded.
With the EDF torquing complete, and the thermal blankets removed from the ORUs, the SSRMS was commanded to operational at 112/15:54, followed soon afterwards by activation of the video components. All component response was nominal except the LEE B Camera Lamp which crew reported had failed to illuminate. Figure 5 shows the mission configuration at this stage. The power up to KA, Operational, and activation of the Video components were the first functionality checkouts as listed in Table 1. Following this checkout, a series of static checkouts were commanded from the MCC-H Figure 4: SSRMS Boom unfold by EV1 on ROBO console – Limping, Safing, video routing SRMS - EV2 positioned to begin EDF (OCR 2,3,4 in Table 1) and JEU diagnostics insertion at the hinge (NASA Photo). were fully successful. The IVA crew then commanded the first robotic motion to elevate Riding the Shuttle RMS in ‘cherrypicker' mode the booms to a prescribed angle to permit a within an Articulating Portable Foot Restraint Single Joint Mode step-off from the passive (APFR), EV1, manually unfolded the SSRMS FSEGF on Flight Day 5 (Figure 6). booms. EDF fasteners were used to lock the The robotic boom raise is a unique maneuver for the SSRMS. While latched to the SLP, the
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SSRMS is in a configuration that is ordinarily and latch. OCR’s 5 to 7 in Table 1 were prevented from motion by the SSRMS Arm completed in the process of Tip LEE B FSEGF Control Software (SACS). The Robotic Boom release (111/ 11:00 GMT) and a series of limited Raise, made possible by a special Payload single joint maneuvers in both positive and Control Parameter Reconfiguration software file, negative directions were exercised while permits SACS to proceed with limited motion translating toward the grapple fixture (Figure 8). under simultaneous singularity, self-collision, Near the destination point, the Tip LEE was and double grappled conditions. oriented for a view by the Elbow camera. A LEE calibration and checkout was performed (OCR 14) to verify mechanism performance before capture.
Figure 6: Simulated RWS Elbow Camera Figure 7: USLab Robotic View of the Robotic Boom Raise Workstation (NASA Photo) The Robotic Boom Raise also presented a unique The Arm Pitch Plane Change (APPC) mode was opportunity for data collection in support of then evaluated. This mode is made possible by ground based dynamic models of the system. the seventh degree of freedom of this arm; it The maneuver is a controlled dynamic motion in allows the plane of the booms (pitch plane) to be a known geometric configuration. The rotated between stationary Tip and Base LEE’s, Manipulator Dynamic Simulation Facility without effecting the Tip POR or orientation. In (MDSF) mission design model predicts this case the maneuver was required to provide significant load development and motor current clearance for SRMS berthing of the MPLM. demand with a distinct transient character - At this point, the control mode was changed to providing a valuable opportunity for Manual Augmented Mode. In this mode, the tip benchmarking with real system-response motion is a function of SACS controlled telemetry. integrated joint motion as interpreted by the The Force Moment Sensor (FMS) was also input deflection of both handcontrollers. Some calibrated to collect data from the boom raise. limited multi-axis motion was performed This is a unique capability that will provide followed by maneuvering toward the PDGF dexterity to the SSRMS; an ability to feel forces target. and moments from payload captures, berthing or The second conditional OCR for FMS installations, and actively adjust the magnitude characterization data was performed concurrent and direction of applied load. This type of data with the actual PDGF Grapple. This data is collection is the first of three OCR’s supporting required to assess impact of ‘crosstalk’ on the FMS On Orbit characterization, critical to FMS sensor resulting from extraneous forces and assessing its behavior in the orbital environment moments from distortion of the LEE during and adjusting the precision of the Force-Moment rigidization and latch phases. Accommodation (FMA) control algorithm. With the SSRMS Captured, Latched, Mated and Safed, at GMT 113/14:15, a major mission 4.2 Phase 2: Step off to Lab PDGF and milestone was complete, and a test of the Unloaded Dynamic Checkout redundant power string was conducted to confirm availability in the event of failure of the On FD5, a second ‘Recon’ file software prime string. download was commanded by the crew to configure the SACS to support maneuvering toward and Lab PDGF and subsequent capture
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Table 1: Docked/Stage Operations On-Orbit Checkout Plan and Status (Tasks deferrable or nominal for Stage shown in grey, plan for ‘Desirable’ checkouts in Stage Ops not included)
) 4.3 Phase 3: Base Change and Powered Static Checkout with Base LEE B min. OCR Title ( th GMT g
OCR # Following MPLM installation by SRMS, the STATUS Pass (P) COMPL. Deffer(D) Cancel(C) Approx Task Len SSRMS, now double grappled at both LEE’s, Power-up SSRMS from off to keepalive to operational 112/ 13:21 required another APPC maneuver to provide 1 20 P on Base LEE A, prime string 112/ 15:53 EVA clearance for the next days power 2 Safing test 5 P 112/ 18:20 reconfiguration within the J400 panel on the 3 Limping SSRMS 5 P 112/ 18:50 USLab exterior. Such a double constrained Video System Activation P 112/ 16:36 4 25 MANDATORY APPC requires pre-mission structural 5 Release Passive FSEGF 10 P 113/ 11:00 ) justification by case-specific analysis because of 6 Limited Single Joint Test 45 P 113/ 11:36 the significant load development possible within Manual Augmented Mode Checkout 113/ 13:16 7 15 P 12/13 ( the closed system. The SSRMS Joints, the LCA, 8 LAB PDGF Grapple, Tip LEE B, Prime String 15 P 113/ 13:53 and PDGF interfaces were considered in CSA’s 9 Power-down SSRMS, prime string w/ LEE A base 10 P 114/ 12:28 analysis with each found to be within there 10 Power-up SSRMS on prime string from LEE B 10 P 114/ 16:38 respective load limit allowables. 11 Base Change 20 P 114/ 12:38 Similar to the boom raise maneuver, the 12 Power-up SSRMS on redundant string, LEE B 20 P 114/ 16:38 magnitude and character of the load development Intergrated Ops checkout - 7A Ops Dry Run 13 60 D 92% DOCKED OPERATIONS OCR'S COMPLETE and motor current in this geometrically closed 14 LEE B Checkout on prime string 15 P 113/ 12:52 system presented a unique opportunity for 15 FMS Characterization (EDD) During Double Restrained n/a 113/ 16:41 dynamic model validation and FMS APPC (ongoing data collection) Performed concurrent P characterization objectives. In accordance with w/nominal ops CSA’s requirements, MCC initiated ground 16 FMS characterization data (normal format telemetry) n/a 113/ 13:53 commanding was made for data collection using during PDGF grapple, LEE B, prime string. Performed P Extended Data Dump (EDD), to increase the concurrent w/nominal ops (#12a) frequency and subunit access of the telemetry 17 FMS characterization data (normal format telemetry) n/a 112/ 19:01 during robotic boom raise (Part 1 of multi-mission data sampling. P collection) Performed concurrent w/nom ops HIGHLY DESIRABLE As preparation for the second EVA began, ground control issued power-down commands to Loaded Manual/Single Joint Maneuvers. 112/ 18.43 ) 18 30 P the prime string (OCR 9), followed by Base
118/ 21:04 7/10 ( Change command from LEE A to LEE B (OCR FMS data collection (EDD) during Loaded (SLP) 19 n/a C maneuvers for DTO 264) Performed concurrent with 11). These steps began the process to change the 20 Handoff SLP to SRMS 30 P 118/ 21:04 Power / Data base from the SLP FSEGF to the FMS Characterization Data Collection during SLP n/a Lab PDGF. With required power inhibits in 21 C Handoff. Performed concurrent w/ nominal ops (#23) place, EV2, mounted on the Shuttle RMS, 22 Video Distribution Unit (VDU) Routing Test, LEE A 10 P 112/ 19:35 disconnected and reconnected the redundant
23 LEE A Checkout on prime string 15 D 70% DOCKED OPERATIONS OCR'S COMPLETE string power / data connectors within the J400 24 Powerdown SSRMS from redundant string,LEE B 10 P 114/ 17:07 Panel (Figure 9). With the connections made, the 25 Tip LEE Camera Checkout 5 KA command was sent – and at 14:07 a ‘Failed 26 Unloaded Manual Mode Test . 20 Keep Alive’ command response was received on 27 L-48 hr Checkout 180 the RWS workstation and the ground control monitors. Immediate troubleshooting response 28 Extended Joint Range test (Part 1 of 2 string 90 OCR'S configurations for Single Joint Mode evaluation) was initiated. EV2 initially proceeded as planned Single Joint Mode test on Other (Prime) String (Part 2 118/ 19:59 with connection of the Prime power / data 29 20 P or 2 string configurations) connections. The power to KA command 30 Grapple LAB FRGF with Tip LEE A, Prime String 15 succeeded on the Prime string; supplying a 31 Handover from one RWS to the other 10 MANDATORY critical single string of thermal power to the 32 Power-down SSRMS on prime string from LEE B 10 P 114/ 22:39 SSRMS. Real time instructions were read up to 33 Release LAB FRGF in LEE Auto Mode, tip LEE A, 15 the EVA crew to disconnect and reconnect Redundant string connectors within and then upstream of the J400 34 Pitch Plane Change Test 10 P 113/ 13:40 panel. While checking the PDGF connections 35 Grapple LAB FRGF with Tip LEE A, Redundant String 15 made during a Flight 5A EVA, EV2 observed 36 Power-up SSRMS from Base LEE B, Prime string 20 114/ 17:02 the PDGF horseshoe connector to be in-place P ) (repeat #19 with RWS redundant bus ch B) and clearly nominal in appearance. However,
Release LAB FRGF in LEE Auto Mode with tip LEE A 5/17 37 15 ( following disconnect and reconnect, KA power on Prime string 38 Line Tracking Test 20 39 POHS Performance Test 20 Complete checkout of SSRMS camera functionality 30% DOCKED / STAGE OPERATIONS 40 240 COMPLETE
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was successfully commanded on the redundant The SLP was moved to an overnight park string. With power successfully applied on both configuration; the objective of the maneuver was strings, the remaining powerup checkouts with to create additional boom clearance with the LEE B Base were completed through ground SRMS during its MPLM (Mini Pressurized commanding (OCR 12,24,32,36). logistics Module) uninstall the following day. The ensuing days of planned operations, including valuable loaded checkouts and 7A rehearsal activities, were frustrated by failures in all three of the ISS Command and Control (C&C) Multiplexer Demultiplexer (MDM) computers. After the first failure, the SSRMS parameters used by SACS were reloaded using a ‘checkpoint data’ reset procedure designed to deal with this type of contingency. However, the PLCP and coordinate frame configuration, although workable, was not ideal for the intended maneuvers. Reconfiguration of the SACS files, ordinarily a simple crew procedure was prevented because of the failures which included C&C MDM loss of contact with the Mass Storage Devise (MSD) from which the files are downloaded. As NASA and contractor teams worked to Figure 8: SSRMS performing limited understand and correct the problem, immediate Single Joint Mode Checkout (NASA troubleshooting and workaround response was Photo) initiated within the ground control infrastructure established for MSS operations between MCC Houston and CSA St. Hubert. The immediate priority was to handoff the SLP to the SRMS, completing all of the CSA sponsored Mandatory checkout requirements for docked operations (OCR’s 1-12) and allowing the arm to maneuver to the unloaded stow configuration, safe for vehicle docking and reboost loads. Trajectory replanning schemes were pursued to allow this operation with the existing files configuration, single joint maneuvers and minimal I/O and file transfer interactions with the CC MDM. In one option, an alternative Figure 9: EVA2, J400 panel trajectory was developed for maneuvering to the reconfiguration to LEE B as base (NASA original handoff position using Single Joint Photo) Maneuvers only. The second moved the handoff to a position where C&C MDM induced failure could not physically interfere with SRMS during 3.5 Phase 4: Loaded Checkout and SLP MPLM reberth. Handoff Another constraint to be addressed was the loads impact to the SSRMS Joints of the next days The SLP was uninstalled by IVR in the first planned Station reboost and docking of the robotic motion from this operating base. Russian Soyuz, scheduled for the following Coordinate frame and Payload Control Parameter week. In parallel with the trajectory design, CSA files were again downloaded by the crew. These Mission Operations performed arm dynamic reconfigure the SACS to control the motor analysis for the overnight park position for both speeds for the payload mass, and change the of these scenarios, and all configurations translation of handcontoller inputs to operator- intermediate to the handoff position where a intuitive motion of a logical POR on the payload. potential C&C MDM failure could strand the arm.
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As the Station computer problems persisted, a handcontoller inputs to control the actual motion two-day extension of the Orbiter stay was steps. required to provide essential communications Robotic activities mandatory within the docked and telemetry downlink, also disrupted by the operations timeframe had been completed with outage. The replanning forced cancellations of the exception of a dry run of the 7A Airlock non-Mandatory FMS characterization and installation trajectory. . Pending resolution or dynamic model validation OCR’s during loaded enhanced understanding of station software maneuvering and handoff (opportunity OCRs 19 management requirements, the remaining and 21 in Table 1). Mandatory checkouts, including full joint range At approximately GMT 118/ 20:00, with the test, 7A mission dry run, and some LEE A minimum requirement of two of three C&C capture exercises, were deferred to stage MDM’s active with MSD communication, operations. SSRMS operations were resumed. In another demonstration of the versatility of the robotics system, a plan of combined ground and crew commanding was implemented to conservatively minimize interaction with the C&C MDMs. The SLP was maneuvered in single joint mode at vernier rates through a new kinematic trajectory to the original handoff position over the Orbiter payload bay (Figure 10). From inside Endeavor, Chris Hadfield grappled the SLP FRGF using the Shuttle RMS. At GMT 118/ 21:04, the SSRMS LEE A was released from the SLP FSEGF. Since the FSEGF has no guide cams, considerable pre- flight analysis had been performed at CSA to understand and quantify any lateral displacement at latch retraction resulting from residual energy in the two manipulators. The potential for a minor impact of some grounding tabs had been Figure 11: Handoff of the SLP from identified. However, no motion was apparent to SSRMS to SRMS for return to the payload the crew or CSA/JSC ground teams carefully bay (NASA Select). studying the telemetry and video downlink in real time (Figure 11). 4.0 Conclusion
The difficulty seating the EDF fasteners into the hinges of the unfolded booms on EVA 1, is speculated to be a result of the 0 g environment unexpectedly improving the hole alignment. Thus requiring additional expansion of the fastener to provide secure interference. There is no concern for the integrity of the joint The failure of the LEE B CLA light is under investigation. Operationally this presents no impediment since LEE B is the operating base and will not need the light until MBS delivery in early 2002. Manual reconnection of the PDGF redundant Figure 10: Loaded Single Joint string connector was required following the Maneuvers to Handoff failure to command KA on EVA 2. Crew has subsequently reported that the running torque of The unloaded manipulator was maneuvered to the connector seemed to drop after 11 of the 20 the stow configuration using the same low required turns. This suggests the possibility a impact regimen of ground commanded mode connection criteria based on number of turns changes, followed by crew RWS and
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may not have been sufficient to ensure the 5.0 References required 10 ft/lbs for proper function. Dynamic performance data (including FMS P.K. Nguyen and P.C. Hughes, Teleoperation telemetry, motor currents, and joint rates) are and Robotics in Space, Progress in Astronautics under review with no detailed results yet and Aeronautics, Vol. 161, AIAA, Washington, available. Real time scrutiny of these parameters DC, 1994. has revealed no significant departures from expected performance, although some higher C. Covault, ISS Computer Crisis Slows than expected motor currents/friction were Canadarm Tests, Aviation Week and Space observed during some operations. Technology, April 30, 2001. The C&C MDM difficulties, and impact to robotic operations, remain under review. The overall station command and control software is modified as each new element is added. It was speculated that the additional software load may have played a role in the computer problems. Other functions involving I/O to the C&C MDM or file transfer may also be associated. SSRMS operations will continue to minimize impact to this system until the problem is resolved or better understood. Of the OCR’s designated Mandatory for docked operations due to requirements for Shuttle resource, 92 % (12/13) were successfully completed and passed. As the highest priority tasks for the mission, this indicates a resounding success for the SSRMS deployment mission. The 7A Airlock Install Dry Run task, designated docked-mandatory was deferred to stage due to delays resulting from the C&C MDM problems. This is not a task required for equipment performance assessment. 70% of the Highly Desirable OCR’s, also in the ISS configuration at completion of 6A docked-Mandatory category, were completed Docked operations, SSRMS in Stow and passed. LEE A Checkout on prime string position (NASA Photo) was deferred to stage operations, and the opportunity FMS characterization tasks were cancelled as a result of the C&C MDM difficulties. In addition 30% of the ‘deferrable’ (Shuttle not required) Mandatory checkout tasks were completed, and some get-ahead OCR’s nominally planned for stage operations were completed. The completion statistics are summarized with Table 1. For every checkout task, real time assessment of performance telemetry was studied by CSA, MD-Robotics, and NASA robotics personnel in the CSA SOSC, and MER in Houston. Performance was exemplary with no failures and no anomalies significant to the upcoming operational requirements.
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