clinometers ping gu

8/3/2019 Clinometers Ping Gu

1/13

Clinometers for

Structural Engineering

CEE 398

Ping Gu

University of Illinois


2/13

Outline:

Application and Classification

Optical Inclinometer

Mechanical Inclinometer

Electrical Inclinometer Capacitive Accustar

Inductive RVDT

Resistive RPS and Applied Mechanicss tiltmeter

Special Issue: Clinometers for dynamic testing RVDT

Clino2000

Force Balance Inclinometers


3/13

Application: Clinometers are also called inclinometers, tiltmeters. the performance of structures under loads, such as curvature of beams and plates

the effects of excavation and tunneling on existing structures

the rotation of dams, piles, retaining walls, struts, anchors,pipelines

road grading and paving

pipeline leveling

crane overturning-moment alarms

Classification according to reference-system:

gravity referenced: angle w.r.t. vertical gravity vector locally referenced: angle w.r.t its housing

according to principle:

Optical

Mechanical

Electrical

Applicationand Classification


4/13

360 degree range

1 sec reading,

estimations to 0.2 use bubble

Static only

single reading



5/13

Coincidence Lever

bubble

screw

accuracy: 0.25 sec

sigle reading by eye, static only

Pendulum Clinometer

pendulum

gravity referenced accuracy: 1min 30 sec

single reading by eye, static only



6/13

Capacitive:

AccuStar

Clino2000

Inductive: RVDT

Resistive:

RPS Applied Mechanicss tiltmeter

Other types, such as strain-gage transducers, force

balance inclinometers

Electrical Inclinometer


7/13

AccuStar

Size: 2.6 in diameter 1.2 in height

Weight: 20 oz

Total range: +/- 60 degree

Linear range: +/- 45 degree Resolution: 0.001 degree

Linearity: +/- 0.1 degree in 10

Temperature range: -30~65C Output: digital pulse width; serial

data; ratiometric; analog

Price: $139

Capacitorplate

intwo halves

etchedtoformtwovariablecapacitors

dielectricliquidandinert

gas

half-filled


8/13

RVDT Principal: similar to LVDT

two primary coils and two secondary coils wound symmetrically on a large-diameter insulated robbin

magnetic cardioid-shaped rotor

mutual inductance varies and produces an output

Range: 20 degree Linearity: 0.5% ~ 1.0% fsd

Size: 38.1mm in diameter, 40mm in height

Weight: 250g

Supply voltage: 3V ac to 30V ac Can be used for dynamic testing

Advantages and disadvantages: similar to LVDT (see my filePotentiometers)

Locally referenced

Usin}


9/13

RPS (Rotary Position Sensors) Principal: similar to POT, except that the wires are wound on a cylindrically shaped

core.

IT9101: magnetically-damped pendulum; conductive plastic film

Range: 0-45 degree

Resolution: essentially infinite

Accuracy: 2.0% full stroke

Size: 5 inches in diameter, 3.73 inches in thickness Weight: 11 lb

Supply voltage: 30V AC or DC

Can not be used for dynamic testing, but can withstand up to 10g to 2000Hzenvironmental shock with its added damping

Advantages and disadvantages: similar to POT (see my file Potentiometers)

Locally referenced


10/13

Applied Mechanicss tiltmeter Resistive, gravity referenced

Principle: Size: 2x2x0.64 inch Weight: 15 g

Range: 25

Resolution: 0.01 microradians ($0.0006) Linearity: 1% over half span, 2.5% over full span

Supply voltage: +8 to +24 VDC @7mA

Analogue or digital outputs

Measure rotation in two orthogonal verticalplanes

High damping of vibration, being used for dam

and earthquake monitoring


11/13

Special Issue: Clinometers for Dynamic Testing RVDT

Clino 2000 Priciple:

pendulum suspended by the Archimedes helical spring, between two electrodes

pendulum swing, changing the capacity between the pendulum and the twoelectrodes

RC-oscillator transforms capacities into different frequencies

the ratio of the two frequencies available is used as the primary signal

patent protected in most countries

Price: $2760

Range: 45 temperature compensation

Highest possible precision

resolution depends on sampling time

Max error in 24hr for 10 range: 0.055%FS+0.15% RO

integrated DYNAM calculating and displaying static and dynamic inclinations


12/13

Special Issue: Clinometers for Dynamic Testing(continued)

Force Balance Inclinometers Principle: closed-loop torque or force balance servo system

torsional flexure-supported moving mass

servo system electronics

torque motor feedback sensor

gravity-referenced

Lucas Control Systems

Ranges available: 1 to 90

Shock survival: 1500g Vibration endurance-sinusoidal: 50g

Vibration endurance-random: 35g rms, 20 Hz to 2000 Hz

Respond to changes in angle 0.1 sec or slope 0.000006 inch/foot

Hysteresis less than 0.0005% of full range

Many angular accelerometers are based on the same priciple.

PositionsensorMass

Torquemotor

Electronics

Damping

ServoAmp

DC output

DC input


13/13

Conclusion:



Electrical Inclinometer

Capacitive Accustar Clino2000

Inductive RVDT

Resistive RPSand Applied Mechanicss tiltmeter

Other types: Force Balance Inclinometers

Those underlined are suitable for dynamic testing

Those bold-faced are locally referenced, others are gravityreferenced.

clinometers ping gu

Documents