Middeck Active Control Experiment-II (MACE-II) - 07.15.14
ISS Science for Everyone
Science Objectives for Everyone Tested self-reliant, adaptive technologies that can detect problems with ISS hardware and correct those problems as needed. These technologies decreased the effects of vibration in ISS allowing engineers to design future spacecraft and facilities with lightweight, inexpensive materials without sacrificing the stability demanded by sensitive payloads.
Science Results for Everyone
Robot repairman at your service? This investigation tested self-reliant, adaptive technologies to detect and correct problems with International Space Station hardware without human intervention. Using algorithms based on information from on-board sensors and actuators, the system autonomously reduced unwanted vibrations by a factor of ten. The algorithms were able to adapt to a failure of a primary actuator on the system and still decrease vibrations by a factor of six. This technology will allow engineers to design future spacecraft and facilities with lightweight, inexpensive materials while maintaining stability demanded by sensitive payloads.
United States Department of Defense Space Test Program, Johnson Space Center, Houston, TX, United States
Air Force Research Laboratory, Albuquerque, NM, United States
Langley Research Center, Hampton, VA, United States
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
Department of Defense (DoD) - Retired
ISS Expedition Duration
November 2000 - August 2001
Previous ISS Missions
- As experimentation takes place on the ISS, one prominent goal is to develop the next generation of smart spacecraft, able to make decisions and solve problems without human intervention.
- The launching of a spacecraft subjects it to vibrations. The most severe oscillations are felt at the cones at the top of the rocket. And even though they may not be catastrophic to the craft itself, these vibrations can damage the vehicle's instrumentation during the ride into orbit.
- MACE-II examined the performance of controlled payloads performing pointing and tracking tasks on the multibody platform and tested models for satellite control of the station's sensors and actuators.
The Middeck Active Control Experiment-II (MACE-II) will allow engineers to design future spacecraft and facilities with lightweight, inexpensive structures and materials without sacrificing the stability demanded by sensitive payloads. MACE-II, the first hands-on experiment on board station, consists of two basic parts designed to detect and compensate for vibrations. The multi-body platform (MBP) test article, which is the structure undergoing tests, has four 1-inch-diameter struts connected to five nodes. It is loosely tethered in the aisle between racks during operations and is stowed between operations. The entire platform has 20 separate sensors that monitor vibration. The experiment support module (ESM) is a self-contained computer with a power interface to the EXPRESS rack and an umbilical connection to the MBP.
During experiments scientists used a gimbal on the MBP to create a disturbance at one end of the platform. The ESM detected these movements and, using an adaptable set of algorithms, calculated the opposing forces to be applied at the opposite gimbal, thereby stabilizing the platform. The algorithms could be adapted to changes due to moving parts, variations in temperature, and normal wear and tear on mechanical systems.
A collaborating team at MIT planned to study how control systems such as that used for MACE-II can be applied to hardware and systems that change over time, such as telescopes, antennas, and robotic arms that must be moved to perform specific duties.
MACE-II also tested self-reliant, adaptive technologies that could detect problems with ISS hardware and correct those problems as needed. This would reduce the amount of crew and ground-based personnel time required to monitor and repair Station hardware. This technique is also critical for control of large flexible structures that must perform precision pointing and tracking missions.
Autonomous adaptive control technology demonstrated by MACE-II can be used in any vehicle that must negotiate turbulent airstreams and atmospheric changes. It can be used to develop smart, problem-solving auto pilots for commercial jets or better guidance and pointing systems for military aircraft.
Bill Shepherd, who operated MACE-II during Expedition 1, and Susan Helms, who took over the operation for Expedition 2, received preliminary training at Johnson Space Center and additional computer-based training while on Station. Power for MACE-II was supplied by EXPRESS rack.
MACE-II operations were carried out in twelve 4- to 8-hour sessions. Data downlink and control uplink occurred between sessions. On July 30, 2001, the Expedition 2 crew deactivated and stowed MACE-II for its return on STS-105.
MACE-II provided data autonomously (no human intervention or prior knowledge of the system), decreasing the effects of vibration in moving structures in space. Algorithms were developed to control mechanical systems in real time using only information from on-board sensors and actuators to respond to changes in the system. The system was able to reduce unwanted vibrations without human intervention once it was turned on. These algorithms were able to "adapt" whenever they sensed changes in vibration or the loss of a sensor or actuator.
Fourteen test protocols were completed during Expedition 1, and an additional 62 test protocols were completed during Expedition 2. The MACE-II unit, which was returned on shuttle flight STS-105, successfully completed all its experiment objectives associated with the AFRL Science Team while on station. On orbit they demonstrated a decrease in vibration by a factor of ten while the system was under control. They then showed that their system could adapt to failure of a primary actuator on the system and still decrease vibration by a factor of six.
However, due to data downlink constraints, the MIT Science Team was unable to meet its science objectives. The MIT team required downlink of specific on-orbit tests to build its control algorithms. By the time data were provided to the university, there was insufficient time to uplink the commands to run the critical experiments. (Evans, et al. 2009)
Davis LD. Economical and Reliable Adaptive Disturbance Cancellation. Air Force Research Laboratory Technical Report; 2002. [DoD Clearance is needed to view this paper]
Ninneman RR, Founds DB, Davis LD, Greeley S, King J. Middeck Active Control Experiment Reflight (MACE II) Program: Adventures in Space. AIAA Space 2003 Conference and Exposition, Long Beach, CA; 2003 September 23-25
Ground Based Results Publications
Blaurock C, Yung JH, Miller DW, Kenney S. Nonlinear Modeling and Control for the Middeck Active Control Experiment Reflight. AIAA Space Technology Conference and Exposition, Albuquerque, NM; 1999 4589.
Hyland DC, Scharf DP, Scharf DP. Adaptive Neural Control for MACE II. AIAA Space Technology Conference and Exposition, Albuquerque, NM; 1999 4588.
McEver MA, Leo DJ. Adaptive Low-Authority Control Algorithms for Precision Space Structures. AIAA Space Technology Conference and Exposition, Albuquerque, NM; 1999 4585.
Shelly SJ, Sharp TD, Denoyer KK. Robust Line-of-Sight Stability and Jitter Compensation Using Spatio-Temporal-Flitering Based Control. AIAA Space Technology Conference and Exposition, Albuquerque, NM; 1999 4587.
Davis LD, King J, Greeley S, Hyland DC. Autonomous System Identification and Control of MACE II Using the Frequency Domain Expert Algorithm. AIAA Space Technology Conference and Exposition, Albuquerque, NM; 1999 4586.
Ninneman RR. Middeck Active Control Experiment Reflight (MACE II) Program: Lessoned Learned. AIAA Space 2000 Conference and Exposition, Long Beach, CA; 2000 5092.
Ninneman RR. Demonstration of Adaptive Structural Control in Space: Middeck Active Control Experiment Reflight (MACE II) Program. 51st International Astronautics Congress, Rio de Janeiro, Brazil; 2000 I.04.03.
Davis LD, Greeley S, King J, Ninneman RR. In Flight Autonomous System Identification and Control of MACE II Using the Frequency Domain Expert Algorithm. AIAA Space Technology Conference and Exposition, Albuquerque, NM; 2001 Aug 28-30
Middeck Active Control Experiment
NASA Fact Sheet
NASA Image: ISS002E6721 - Susan Helms, Expedition 2 flight engineer, works with MACE-II, which is shown "floating" in the microgravity environment of ISS.
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NASA Image: ISS01E5216 - MACE-II hardware on board ISS during Expedition 1.
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