Instrumentation

Transducers Used in Vehicle Dynamic Tests

 Servo Steering Throttle and Brakes: Heitz System 4
 Servo Steering: Heitz Sprint 3 
 Speed and Heading Angle: “V Box” GPS 


Wheel speed/Tire deflection/suspension travel: A hollow-shaft encoder runs on a plate supported by lugnut extensions. The body of the encoder is in a frame that is connected through a pin/clevis joint to a vertical shaft. The vertical shaft travels through a fender-mounted eyebolt assembly which contains a string encoder for measurement of suspension travel. The encoder measures wheel speed. A downward-facing ultrasonic distance sensor measures tire deflection. 

Steering wheel angle/effort: "second steering wheel" normally clamps to original steering wheel, with adjustable arm to suction cup on windshield. Optional attachment is directly to the steering column, replacing the vehicle steering wheel.  Strain-gauge paddle wheel element with built-in amplifier measures steer effort. Optical encoder angle readout. Calibration by special torque wrench. Used in lane-change and free-control studies.   

Throttle position: Tap into vehicle’s throttle position potentiometer. 

Throttle position: String encoder attached to accelerator linkage. 

Brake effort: LEBOW 3363-200 brake pedal load cell. 200 pounds full-scale; linearity 0.1 percent. Cal by precision 100 lb TROEMER 9082 NBS Class F weight. 

Brake effort: LEBOW 3363-300 brake pedal load cell. 300 pounds full-scale; linearity 0.1 percent. Cal by precision 100 lb TROEMER 9082 NBS Class F weight. 

Yaw velocity: NORTHRUP Nortronics 3-axis DC-DC rate gyro package, P/N 77025, SN17 and SN18 (2 units, one installed in Humphrey Package). 90 deg/sec FS; linearity 0.5 percent; hysteresis 0.1 deg/sec; threshold 0.01 deg/sec. Calibration on 36 degrees/sec rate table. 

Yaw acceleration: SYSTRON-DONNER INERTIAL DIVISION Fluid-Rotor Angular Servo Accelerometer, Model 4591. Full-scale 570 Degrees/sec/sec; Linearity 0.2 percent. Calibration check on pendulous swing. 

Yaw acceleration: COLMBIA  Force balance Angular Accelerometer Model SR-107VFR.  1.0 to 100 rad/sec/sec Selectable Full Scale ±5v., ± .2 percent FS.

Linear acceleration: Force-balance servo accelerometers: SYSTRON-DONNER Models 4383 and 4310; SUNDSTRAND Models 303 and 305, SUNDSTRAND Model 2180 "MiniPal". Several of each, with full-scale 0.25 to 10 G, linearity 0.05 or 0.1 percent. Calibration on sine table with precision gauge blocks.

Stabilized Inertial Reference System: Pitch & roll Angles, X,Y,Z accelerations, pitch, roll, yaw velocities: HUMPHREY Stabilized Accelerometer System, Model SA07-0304-1. Vertical/free gyro can be used with servo erection (at 2 deg/min) or as low-drift free gyro caged until beginning of maneuver. Angles are calibrated against accelerometers by forced drift. Gimballed accelerometers held vertical by gyro are SUNDSTRAND Linear Servo Accelerometer Model 303. Full scale 1 g, linearity 0.05 percent. Calibration ±1 g by tilting. Package is modified by installing NORTRONICS rate gyro package (S/N 17) inside and incorporating power supplies in box lid.  Weight 38 pounds,

Strap-down Inertial Measurement System (IMU1): X,Y,Z accelerations, Roll, Pitch, Yaw Rates. Assembly consists of three orthogonally-mounted SUNDSTRAND Model 303 linear servo accelerometers, together with three Systron Donner GyroChip rate sensors.. Dimensions 4x4x3.5 inches, 3.2 pounds. Color is yellow.

Miniature Strap-down  Inertial Measurement Ststem (IMU2): X,Y,Z acceleration, pitch, roll, yaw velocities. Assembly consists of  three orthogonally-mounted  Sundstrand Mini-Pal servo accelerometers and three Systron Donner GyroChip rate sensors. Dimensions 3.5x4.5x2 inches, weight 1 pound. Color is blue.

Ultrasonic Distance: MIGATRON Model RPS-401A.  Analog output 0-10 volts, zero & span adjustable.  Full-scale span 5 to 30 inches, minimum distance 5 inches, maximum distance 40 inches.  Operating frequency 212 kHz.  Accuracy ± 0.040 inches or ± 0.3 percent, whichever is greater.

Wind speed and direction: Assembly consists of a lightweight rotating cup anemometer and a fast-response, fiberglass-over-styrofoam wind vane, specially designed by Princeton University Aerospace Department.