OVERVIEW

The Operational System for Inspection, Research, and Instrument Support (OSIRIS) is a remotely operated free-flying camera robot. Designed to fly in air, OSIRIS has full six axis control and can serve as a test platform for several areas of research including attitude control, path planning, inspection tasks, and human-robot interaction.

Similar vehicles designed in the past include SCAMP and SCAMP SSV. These vehicles are twenty-six sided teleoperated free-flyers measuring twenty-eight inches in diameter. Also developed at the SSL, these vehicles use ducted fans for propulsion. Other camera free-flyers use nitrogen cold gas thrusters or other gas propulsion systems. OSIRIS implements an alternative propulsion system, the centrifugal pump-jet propulsor. Upon vehicle integration, the system was tested in the micro-gravity environment on board NASA's KC-135 Weightless Wonder V.

Testing was done in March 2004 in conjunction with the Reduced Gravity Student Flight Opportunities Program at Johnson Space Center. These tests were used to measure the functionality and effectiveness of the propulsion system and to determine a preliminary characterization of the vehicle dynamics. Analysis demonstrated that the propulsion system can effectively run a space simulator vehicle in air in a microgravity environment.

VEHICLE HARDWARE AND CONTROL DESCRIPTION

OSIRIS was designed around the centrifugal pump-jet propulsion system to fully fit within the ten-inch diameter spherical casing. The total vehicle weight is under seven pounds. The vehicle uses a motor driven impeller to pump air through three rotating nozzles with variable outlet areas. This allows for full six degree-of-freedom motion. The intake has a central mount point for an approximately 1.5"x1.5"x1.5" camera. A front and rear fairing fit between the nozzles and intake. All external components were cosntructed on a rapid prototype machine out of ABS plastic.


The vehicle uses three sail winch servos to control the nozzle rotation and three feather servos to open and close the valve outlet areas. The servos are controlled by a controller board that accepts serial data from a ground based computer. Two control modes have been implemented for the vehicle: keyboard and flock of birds. Keyboard control takes in key presses to manually test individual degrees of motion. Flock of birds is a motion detector that reads angles of a transmitter relative to a base sesor. With the transmitter attached to the pilot's hand or arm, control of the vehicle will mimic pilot motion.

Power and serial commands are fed to the vehicle from the ground control station through a tether. OSIRIS uses five PowerSonic PS-6100 lead acid batteries to run the motor and computer boards. The main computer is a Diamond Systems Prometheus PC/104 board, designed for embedded systems applications. It has a ZFx86 100 MHz CPU and 32 MB of RAM. In addition, the Prometheus board has four on-board serial port connections which are used to communicate with the Flock of Birds sensor and the servo control board. This board receives power through a 25W Jupiter-MM-LP power supply.

OSIRIS TEAM

Principal Investigator: Dr. David L. Akin
Hardware Lead: David Hart, Emily Tai
Software Lead: Mike Naylor
Development and Testing: Matt Hughes, Alice Ryan