GENERAL APPLICATION NOTES

TERMS and DEFINITIONS

CW	Clockwise
CCW	Counterclockwise
NULL	Special angle generally associated with the center range or ZERO angle.
NULL IMPEDANCE	Resistance equivalent measured between the outer terminals while the sensor is at NULL and is under AC excitation. { Ohms, KOhms, MOhms }
MAXIMUM RANGE	Absolute maximum CCW to CW angular displacement in which the sensor generates monotonous output. { arcdeg, arcmin, arcsec }
LINEAR RANGE	Absolute maximum CCW to CW angular displacement in which the sensor maintains the LINEARITY characteristic. { arcdeg, arcmin, arcsec }
LINEARITY	Absolute maximum deviation between the corresponding calculated BEST FIT straight line and the RAW output of the sensor in the specified CCW to CW range. The linearity error could be represented in { % of full scale } or as angular error at each angle in { arcdeg, arcmin, arcsec }
SYMMETRY	The Symmetry characteristic of the sensor is defined as the result of 100 * (V+angle - V-angle) / ((V+angle + V-angle) / 2). { % }Vangle = (output at specified angle)
RESOLUTION	Absolute smallest repeatable angular displacement which results in consistent change in output within the linear range. Sometimes called ( Sensitivity ). { arcdeg, arcmin, arcsec }
REPEATABILITY	Angular error calculated from differences in outputs of the sensor measured at same angular position before and after random angular displacement. Special angle of importance is NULL with corresponding NULL REPEATABILITY characteristic.{ arcdeg, arcmin, arcsec }
RESPONSE TIME	Elapsed time until the sensor reacts to a tilt disturbance. { msec }
TIME CONSTANT	Elapsed time measured from the end of the tilt agitation until the sensor is within 90% of STEADY STATE output. { msec }
TOTAL SETTLING TIME	Elapsed time measured from the end of the tilt disturbance until the sensor is at STEADY STATE output or within the repeatability requirement. { msec }
CROSS TILT ERROR	Angular error in sensors output while the sensor is revolved about its non sensitive perpendicular axis. { arcdeg, arcmin, arcsec }
EXCITATION	Periodic signal with 1Khz / 3-5Vp-p is recommended.

WARNING:

Use of DC current can permanently polarize the electrolyte and irreversibly damage the sensor. Wave soldering is not recommended when installing Polymer based DX-type tilt sensors on PC boards.

Electrolytic tilt sensor have for many years proven to provide a reliable way to measure tilt angles in static and dynamic environments. The sensor, when connected to an appropriate electronic conversion module, provides an output proportional to a corresponding inclination angle.

The output waveform function is monotonous in its full output range. In principal the operation of the tilt sensor resembles the behavior of a potentiometer. The direction of the tilt could be detected as a phase shift in the output AC waveform, or a ( + or - ) sign if DC output option is utilized.

In the case of 4-20 ma option, output currents below 12ma point to a CW tilt, while output currents above 12 ma will refer to a CCW tilt angles. When using RS-232 output option, the sign bit will point out the CW or CCW tilt direction. Due to expensive and complicated timing, counting, and conversion circuitry, PWM ( pulse width modulation ) output option is not recommended when accurate high resolution measurement is required.

In general the sensor is constructed as a sealed cavity with the electrodes partially submersed in the electrolyte. The ratio between submersed areas of the facing electrodes will be proportional to a "resistance" characteristic when AC drive signal is applied. This characteristic is usually called "Impedance" and is expressed in Ohms and measured while the sensor is at Null.

Impedance has the tendency to change with temperature, therefore it is recommended to utilize drive circuits which could automatically alter the drive current while maintaining a steady excitation AC voltage. In some cases it is possible to correct for the thermal drift of the tilt system by factoring in the drift error directly into the output signal or when converting and manipulating data in the computer. For data catalogues the impedance is tested while the sensor is at 25°C.

When using dual axis sensors it is practical to utilize an alternating axis excitation technique. In this method each sensing axis is excited for a fraction of a second, just long enough to produce a stable output for the currently excited axis. For applications where high accuracy is required other avenues of signal conversion are available, and are contingent on individual applications.

Even though tilt sensors are produced for over thirty years, manufacturing methods still depend on costly professionals trained in manual glass forming. Due to sensor's brittle nature, in many cases it requires expensive enclosures and elaborate internal installation to protect the sensor in the event of an accident such as dropping it on the floor. Rugged construction, cost, reproducibility and easy installation were all important design requirements when DX and SX non glass sensors were created. These sensors are constructed from High Temp Advanced Polymers and specially formulated compounds in order to create the first NON-glass polymer based electrolytic tilt sensor. It is rugged, drop resistant and highly cost effective.

The circuit shown on document #10002 is a general propose method for the excitation of any dual axis tilt sensor. This method is based on alternating excitation of both axis by the same waveform generator or clock. Precise synchronization with the output stage will allow proper separation of outputs for both axis. The speed of switching between tilt axis will define the update rate of the output signal. Suggested switching rate is 10 - 100 Hz.

Two SX (single axis) sensors, when center terminals are joined, could be excited using the same principle. In this case sensors could be of different types and provide different range and scale factor characteristics for each axis.

SPECIAL PRODUCTS:

Advanced CMOS design guarantees low current consumption, which makes this module a logical choice for various battery powered applications. As with any of OUR angle conversion modules, you may install the sensor directly on the PCB or remotely. With proper selection of supply voltage and GAIN settings this module may be directly interfaced to standard A/D converters or computer I/O data acquisition boards.

EZ-TILT-5000, advanced programmable dual/single axis LINEAR Analog/Digital output tilt module, is built around a customized state of the art CMOS Microprocessor.  A 2"x 2" assembled PCB provides concurrent Analog, PWM and RS-232 inclination information in two axis of tilt. The module is fully temperature compensated for NULL and GAIN. The system includes full range linearity correction for each axis of tilt and two software adjustable threshold detectors, one for each axis.

 The module uses any two sensor combination of either SX-xxxD-LIN, SX-003D-NULL, SX-xxxD-VIB or SX-COMBO single axis inclination sensors and provides an economical and reliable tilt sensing solution for applications requiring superior Nulling capabilities with concurrent excellent Mid-Wide range LINEARITY, resolution, repeatability and symmetry. Rugged hermetic construction and MIL-SPEC temperature range make these sensors perfectly suitable for numerous high precision OEM, military, medical, optical, automotive, range finder, alignment, automation, robotics and construction angle measurement applications.

 The EZ-TILT-5000 also includes two fully programmable level threshold detector lines that allow the user to set level sensitive alarms for pitch and roll. Innovative design, four set screw holes and small size facilitate uncomplicated mounting.  The system can be easily supplied with two different tilt sensors. This rare option lets users solve special applications when one axis requires high tilt range while the other one requires high resolution. Sensors could be remotely located and calibrated to different ranges if so required.

 Both Analog and PWM outputs are fully software programmable and are updated each read cycle for each enabled axis. The analog output range is top limited by 4Vdc and bottom limited by 1Vdc for the full set angular range. The PWM will output 10% to 90% duty cycle for the set angular range at base frequency of 37Hz.

 Exceptionally stable and consistent performance in temperature variable environments and it's LOW cost make EZ-TILT-5000 the perfect choice for high accuracy leveling applications. In addition to digital filtering the electrolyte may be modified to mechanically filter out errors induced by shock & vibration. Test data could be supplied on 3.5" disk upon special request.

 The module is able to operate in a stand-alone mode with a 4 line x 20 character serial LCD display. The wide range model could operate to +-85 arcdeg covering a total span of 170 arcdeg.  The module is also available on 0.9” x 3.0” PCB for angle measurements in bore hole, tunneling, logging and oil drilling applications.

EZ-COMPASS-3 is a low cost advanced pitch/roll compensated COMPASS / MAGNETOMETER system which is built around a state of the art CMOS  microcontroller utilizing AOSI’s proprietary algorithm and is available in four versions (General purpose, Geophysical Vertical, Geophysical Horizontal and DIVE). All versions output continuous heading, field, dual axis tilt and temperature data over the standard RS-232 and RS-422 interfaces. The AZIMUTH is generated from a 3 axis semiconductor magnetometer with 12 bit ( 0.08 deg ) resolution. The LINEAR tilt information is available with 12 bit resolution for up to +-80arcdeg. The COMPASS is able to output heading information in NMEA-0183 mode.  Easy link via the Hyper Terminal Windows accessory facilitates custom calibration, hard iron compensation, data acquisition, data averaging and data display.

 COMPASS/TILT module is perfectly suitable for numerous navigation, drilling, research, training, construction, entertainment and other precision  orientation, navigation and leveling applications. It is also a great replacement for the FLUX GATE compasses.

EZ-TILT-2000 rev-2 advanced programmable dual/single axis LINEAR Analog/Digital output tilt module is built around a customized state of the art CMOS Microprocessor.  A 2"x 2" assembled PCB provides concurrent Analog, PWM and RS-232 inclination information in two axis of tilt. The module may be temperature compensated for NULL and GAIN. The system includes full range linearity correction for each axis of tilt and two software adjustable threshold detectors.

 The module uses the DX type (DX-045D or DX-008D) dual axis sensors for dual axis mode, or one SX type single axis LINEAR inclination sensors for single axis mode and provides an economical and reliable tilt sensing solution for applications requiring superior Nulling capabilities with concurrent excellent Mid-Wide range LINEARITY,  resolution,  repeatability and symmetry. Rugged construction makes these sensors perfectly suitable for numerous high precision OEM, military, medical, optical, automotive, range finder, alignment, automation, robotics and construction angle measurement applications.

The EZ-TILT-2000 rev-2 also includes two programmable level threshold detector lines that allow the user to set level sensitive alarms for pitch and roll. Innovative design, four mounting holes and small size facilitate uncomplicated mounting. For hazardous applications, tilt sensors could be remotely located.

Both Analog and PWM outputs are fully software programmable and are updated each read cycle for each enabled axis. The analog output range is top limited by 4Vdc and bottom limited by 1Vdc for the full set angular range. The PWM will output a 10% to 90% duty cycle  for the set angular range at a base frequency of 37Hz. 

Exceptionally stable and consistent performance in temperature variable environments and it's LOW cost make EZ-TILT-2000 rev-2 the perfect choice for high accuracy  leveling applications. In addition to digital filtering the electrolyte may be modified to mechanically filter out errors induced by shock & vibration. Test data could be supplied on 3.5" disk upon special request.

 The module is able to operate in a stand-alone mode with a 4 line x 20 character serial LCD display. The wide range model could operate to +-90 arcdeg covering a total span of 180 arcdeg.  The module may be also available on a 0.9” x 3.0” PCB for angle measurements in bore hole, tunneling, logging and oil drilling applications. 

The system includes software adjustable temperature correction coefficients. The user has an option of changing temperature correction coefficients to actively remove NULL and GAIN drift due to continuously changing thermal conditions.

	ADVANCED ORIENTATION SYSTEMS, Inc. 1901 E. LINDEN AVENUE, Unit 22 LINDEN, NJ 07036, USA. Phone: 908-474-9595 Fax: 908-474-9090 sales@aositilt.com http://www.aositilt.com