The computer further includes a gimbal mechanism that allows {HEAD ~ the door} to move relative to {TAIL ~ the linkage mechanism} while constraining the door to the linkage mechanism 
to move relative to
The computer further includes a gimbal mechanism that allows { HEAD ~ the door } to move relative to { TAIL ~ the linkage mechanism } while constraining the door to the linkage mechanism
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH