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. RMS OPERATIONS SUPPORT: FROM THE SPACE SHUTTLE TO THE SPACE STATION Phung K. Nguyen and Michael Hiltz MacDonald Dettwiler Space and Advanced Robotics Ltd. 9445 Airport Road, Brampton, Ontario L6S 4J3 [email protected] , [email protected] Keywords: Canadarm, Canadarm2, RMS, of external sections of the ISS, servicing payloads, space shuttle, space station, operations, support, moving equipment and supplies to different flight data, database, trending, maintenance, flight locations on the Station, retrieving satellites and hardware upgrade, software upgrade. payloads, as well as supporting astronauts during EVA. Together, the Canadarm and Canadarm2 will Abstract be the first two RMS’s servicing the ISS; other RMS’s such as the European Robotic Arm (ERA) Like many other technologies, space robotics has and the JEM (Japanese Experiment Module) RMS evolved significantly over the past twenty years. will join the ISS arm fleet in future assembly Canada in general, and MD Robotics in particular, missions for other payload handling operations. All have contributed a great deal to these advances. these arms will be commonly referred to as RMS’s This contribution is highlighted by the development in what follows. and operations support of MD Robotics’ Canadarm and the second-generation space manipulator, Although they will be attached to different 2 locations - one on the Space Shuttle, and the other Canadarm . In this paper, we will highlight the 2 experience and expertise gained while supporting on the ISS - Canadarm and Canadarm share certain the operation of Canadarm and illustrate how it has common tasks. Despite differences in their influenced both the design and planned operation of respective designs and base locations, similarities in Canadarm2. It is shown that the lessons learned their intended function and modes of operation from this experience are sufficiently general that dictate that they require similar operations support. they can be applied to future space manipulators such as the Special Purpose Dexterous Manipulator, RMS operations support requires broad multi- as well as the Japanese and the European Remote disciplinary technical expertise to perform a variety Manipulators. of tasks ranging from planning, testing, through to execution. Underlying this effort is the common goal of ensuring efficiency, safety and success in 1 Introduction orbit. It also requires coordination and communication between various organizations in different countries using English as the common Over the past twenty years, the Canadarm (also language. known as the Shuttle Remote Manipulator System, or SRMS- Fig. 1) has flown more than sixty times, In this paper, we will highlight the similarities and demonstrating flawless performance while differences between Canadarm and Canadarm2, deploying, maneuvering, and/or retrieving more describe the experiences in supporting the than seventy payloads in support of NASA Space operations of the Canadarm, the planned operations Transportation System (STS) program. Currently, support for Canadarm2 and the hand-over NASA is planning to utilize the Canadarm in the operations that involve both arms. same role for the next twenty years. MD Robotics has spent a significant effort on astronaut training, 2 designing and verifying mission operations, 2 Canadarm and Canadarm telemetry data analysis, hardware and software To appreciate the similarities and differences in the maintenance and upgrades, as well as simulation 2 capability improvements. operations of Canadarm and Canadarm , it is important to highlight the differences in their The Canadarm2 (also known as the Space Station respective designs and capabilities. Remote Manipulator System, or SSRMS- Fig. 2) Canadarm is similar to Canadarm2 in the following was launched and deployed in Flight STS-100 (or * Flight 6A in the International Space Station respects : assembly sequence) in April 2001. Together with other components of the Mobile Servicing System * (MSS) its role includes ISS assembly, maintenance The first bracketed item refers to Canadarm, the second for Canadarm2. a) length (50 ft vs. 57.7 ft); d) gear ratio (1842/1260/738 vs. 1845 b) end effector (standard vs. latching ); /1845/1845 for Shoulder, Elbow and c) working space (6 dimensioned space for Wrist); both arms); e) payload handling capability (up to 586,000 d) stopping distance requirement (2 ft for lbs. payload vs. 205,000 lbs.); both arms); f) mass ( 930 lbs. vs. 3530 lbs.); e) computer-supported modes of operation g) unloaded speed (2 ft/s vs. 1.21 ft/s); (plus non-computer supported modes vs. h) self –collision (N/A vs. possible collision redundant string capability); which is prevented by control software); f) joint controller (digital implementation, i) cameras/lights (1+1 vs. 2+2 for elbow and parameter settable in Canadarm2); tip); g) singularity avoidance; j) force-moment accommodation (N/A vs. h) joint reach limit detection. optional); k) power budget (2050 W vs. 2000 W); l) keep-alive power (N/A vs. 1360 W); m) payload interface (mechanical/electrical only vs. mechanical/electrical/video/data); n) nominal bus voltage (28V vs. 120 V); o) reliability (fail-safe vs. fail-operational); p) maintenance and service (ground-based vs. on-orbit replacement), etc. The above similarities and differences are discussed in full detail in Ref. [1]. Operationally the two arms share many common tasks, such as payload grappling, maneuvering, berthing/ unberthing and EVA astronaut support. In terms of safety, they also share common practices for flight operations procedures (techniques) and flight rules, which is not surprising since the experiences in mission Fig.1 Canadarm and Hubble Space Telescope planning, astronaut training and strategies for controlling the manipulator have been passed on from the Canadarm program to the Canadarm2 program. The experience and lessons learned from the Canadarm and how they have been passed to the Canadarm2 is the inspiration for this paper. 3 Canadarm Operations Support For the purposes of this paper, operations support is defined as those activities before, during, and after mission which are required to ensure and/or improve arm performance following its delivery to NASA. As such, operations support covers simulations, analyses, hardware redesign and tests, hardware maintenance, software maintenance and arm upgrades. 2 Before the Canadarm was commissioned for use on Fig. 2 Canadarm in Flight 6A orbit, it underwent a series of on-orbit verification tests beginning with STS-2 in 1981 and ending with Some key differences between Canadarm and 2 STS-8 in 1983. The tests were designed to verify Canadarm are listed below: the arm performance through a series of tests in the following order: (open-loop) motor control in a) base location (fixed vs. mobile); Direct Drive mode, (closed-loop) joint control in b) number of joints ( 2+1+3 vs. 3+1+3 for Single Drive mode, coordinated operation of all Shoulder, Elbow and Wrist joints in Manual Augmented mode and Automatic clusters/assemblies); mode. A series of Orbiter Primary Reaction c) joint configuration (in-line versus offset Control System (PRCS) tests were also conducted joints); to determine the Canadarm response to externally Page 2 applied loads (from the Orbiter thruster firing). The Mission-specific operations support falls into three payloads handled during this testing are “No- categories: pre, real-time, and post mission payload” (i.e. unloaded arm), Plasma Diagnostics activities. Package (PDP, 344 lbs.), Induced Environment Positive Direction Average Contamination Monitor (IECM, 816 lbs.), Shuttle Steady State Rate Pallet Satellite 01 (SPAS-01, 3172 lbs.), and 27 26 Payload Flight Test Article (PFTA, 7460 lbs.). The WR + PFTA was a “dummy” payload especially designed 25 WY + 24 WP + to simulate the moments of inertia that the 23 EP + Canadarm would experience when handling a 22 SP + 32,000 lb. payload. 21 SY + Average Rate (rad/s) 20 19 The above-mentioned tests were carefully selected 18 to ensure that the arm behavior would be within its STS-41 STS-39 STS-48 STS-52 STS-62 STS-74 STS-77 STS-82 STS-85 STS-87 STS-92 STS-51I STS-103 STS-41D STS-51D STS-31R design range, ensuring that operation did not occur STS-51A STS-51G near a reach limit or arm singularity and loads were Fig. 3 Average Steady-state Motor Rates in kept below “Flight Planning Load Limits”. The Direct Drive down-linked telemetry data also had to be sampled Apart from the essential activities by the Kennedy fast enough to ensure meaningful analyses. This Space Center (KSC) team to install and checkout activity was supported by a number of NASA the Canadarm and payloads in the Shuttle cargo subcontractors such as Rockwell Space Operations bay, there are a number of other activities involving Co., McDonnell Douglas Space Services Co., the Johnson Space Center (JSC) team and NASA TRW, Lockheed Engineering and Sciences Co., the contractors. For example, based on the mission Charles Stark Draper Laboratory, as well as the objective and plan, the MOD (Mission Operations design authority, MD Robotics Ltd. (formerly, Spar Directorate) team at NASA JSC designs the SRMS Aerospace Ltd.) in Toronto, Canada. Before operations checklist that details crew’s procedures missions, the tests were verified via simulations. and Canadarm displays. At the L-24 mark (i.e. 24 After missions, the flight test data was used for months before launch), the preliminary version of simulation validation and simulation model update, the list is published, which is normally in addition to data analysis to support arm accompanied by a list of concerns on viewing performance verification. It should also be noted adequacy, compliance with dynamic clearance that for these missions, the Canadarm was envelope of the cargo bay, etc. The preliminary list instrumented with strain gauges to measure on-orbit is based on kinematics simulations of the Canadarm loads at its Wrist, Elbow and Shoulder.