A two degree of freedom (2 DOF) accelerometer comprising two imbalanced sensing modules (i.e., bar modules having an unbalance) is provided such that two sensing modules are located in the plane to be measured. The two imbalanced sensing modules have force balance and are used to measure linear and angular accelerations in two degrees of freedom. A single modular design is used for both of the axes. Each of the two individual sensing modules has a housing containing a proof mass for each measured output and a support of the proof mass with the support optimized for the sensitive axis selected for sensor output and having high rigidity in all other axes of the support. Also provided is electrostatic servo force balance technology. A proportional-integral-derivative (PID) controller is used to obtain a closed loop bandwidth of 1 kHz and a steady state error of zero for full scale accelerations up to 75 g's and 1000 rad/sec2.

Linear and rotational accelerometer

To detect a vehicle roll-over in good time and with a high degree of reliability, acceleration sensors (Bx, By, Bz) are provided which measure accelerations of the vehicle (FZ) in the direction of the yaw axis (z) thereof, the rolling axis (x) thereof, and the pitching axis (y) thereof. At least one rotation-rate sensor (DRSx, DRSy) is also provided to measure the angle speed of the vehicle (FZ) in relation to the rolling axis (x) thereof and, possibly, also in relation to the pitching axis thereof.

Method and arrangement for detecting a vehicle roll-over

An electronic device for measuring relative angular positional displacement and angular range of motion for body segments and articulating joints of the human skeleton is disclosed. The device has a hand-held interface unit which is placed against the body segment or joint to be tested. Mounted within the housing of the interface unit is a shaft with a pendulum at one end and an optical encoder at the other. As the body segment rotates or the joint articulates, the pendulum swings in the direction of gravity, causing the shaft to rotate. The optical encoder generates an electrical signal representative of the amount of rotation of the shaft. The generated signal is fed to a microprocessor which processes the information and can produce on a display the change in angular position relative to initial angular position or the angular range of motion of the body segment or articulating joint.

Electronic angular position and range of motion measuring device and method

A fault tolerant attitude control system for a zero momentum spacecraft. A zero momentum attitude control system is operable to control spacecraft attitude utilizing data received from an earth sensor, a sun sensor, and the inertial measurement unit. A gyroless attitude control system is operable to control spacecraft attitude without receiving data from the inertial measurement unit. A redundancy management system is operable to monitor an inertial measurement unit to detect faults and to reconfigure the inertial measurement unit if a fault is detected and operable to determine when an inertial measurement unit fault is resolved. A controller is operable to automatically switch the spacecraft from the zero momentum attitude control to the gyroless attitude control when a fault in the inertial measurement unit is detected and is operable to automatically switch the spacecraft from the gyroless attitude control to the zero momentum control upon resolution of the fault.

Fault tolerant attitude control system for zero momentum spacecraft

A method for rapid earth reacquisition of a spacecraft. A three-axis inertial attitude of the spacecraft is determined by rotating the spacecraft about its pitch axis while measuring star patterns. A pitch axis of the spacecraft is aligned with earth's pole axis. The spacecraft is reoriented with respect to an earth-pointing reference frame.

System for geosynchronous spacecraft rapid earth reacquisition

A gyroless vertical indicating device which tracks the local gravity vector independent of horizontal acceleration. A compound pendulum and an angular accelerometer each has a single rotational degree of freedom about a common axis. Rotational motion of the pendulum and of the angular accelerometer about the axis is coupled by a quartz fiber suspension therealong. A signal representative of the relative angular velocity between the pendulum and the angular accelerometer is fed back to a torquing system which maintains the pendulum's orientation along the local gravity vector.

Shigeo Okubo

Papers

Angular accelerometer stabilized pendulum

Device for indicating verticality