The NASA Marshall Space Flight Center has developed a synchronized subsystem for use in an automated docking or station keeping system for docking a chase vehicle with a target vehicle wherein the chase vehicle is provided with a video camera which provides adjacent frames each having a predetermined time duration. A light source mounted on the target vehicle flashes at a frequency which has a time duration which is a multiple of the duration time of the frames, the light being on for at least one frame duration and being off for the remainder of the cycle. An image processing unit is connected to the camera for receiving signals from the camera and subtracting one of the adjacent frames from the other to detect whether the light appears in one frame, both frames or neither frame. If the target light appears in both frames, or neither frame, the image processing unit feeds a signal to a timing circuit to advance the video camera one frame. This process is continued until the target light appears in one frame and not in the other, at which time the process of advancing the video camera is stopped.

Benefits

Potential Commercial Uses

The Technology

A chase vehicle carries a video camera aimed to receive light from the lights on the target vehicle. The video camera provides video frames at a 30 Hz rate, each frame consisting of two 1/60th second fields which are interlaced to form the 1/30th second frame. The lights flash at a 30 Hz rate, with the lights being on during the first 3/60 seconds of a cycle (one and a half frames) and being off for the remainder of the cycle, 9/60 seconds. The camera feeds a signal to an image processing unit which subtracts one video frame from the adjacent frame. If the target lights show in the one frame but not the other the image processing unit feeds a signal to a software processor which controls the docking. If the target lights show in part of one frame but not the other frame, the image processing unit sends a signal to a timing circuit to cause the timing circuit to feed a signal to the video camera to advance the video camera one frame. The process is continued until the target lights show in one frame but do not show in the adjacent frame. From this point on, the video camera is synchronized with the flashing lights and the docking or station keeping procedure is carried out by a docking process controller and thruster hardware.

Patent Number

6,091,345

Contact for Licensing Information

If your company is interested in commercializing the Synchronized Docking System or if you need additional information, please reference case no. MFS-31281 and contact:

Technology Transfer Department
Patent Licensing Information
Mail Code CD30
Marshall Space Flight Center
Email: sammy.nabors@msfc.nasa.gov