An inclinometer or clinometer is an instrument for measuring angles of slope (or tilt), elevation or depression of an object with respect to gravity. It is also known as a tilt meter, tilt indicator, slope alert, slope gauge, gradient meter, gradiometer, level gauge, level meter, declinometer, and pitch & roll indicator. Clinometers measure both inclines (positive slopes, as seen by an observer looking upwards) and declines (negative slopes, as seen by an observer looking downward) using three different units of measure: degrees, percent, and topo. Astrolabes are inclinometers that were used for navigation and locating astronomical objects from ancient times to the Renaissance.

Compass with inclinometer

Military model

Inclinometer Casing

Inclinometer Casing

An inclinometer system has two components: (1) inclinometer casing and (2) an inclinometer measurement system.

Inclinometer casing provides access for subsurface measurements. Grooves inside the casing control the orientation of the inclinometer sensor and provide a uniform surface for

measurements.

Inclinometer casing is usually installed in a borehole. It can also be embedded in fill, buried in a trench (horizontal inclinometers), cast into concrete, or attached to a structure.Portable Measurement Systems

Digitilt Classic System

Digitilt AT System

Portable measurement systems include a probe, cable, and readout. Portable systems are economical because they can be carried from site to site. They are accurate because the entire length of the casing is measured twice in each survey.

The first survey establishes the initial profile of the casing. Subsequent surveys are compared to the initial. Changes in the profile indicate that movement has occurred.

Slope Indicator offers the Digitilt Classic System, which has been the world standard in precision and reliability for many years, and the Digitilt AT System, which takes advantage of newer technologies.

Inclinometers generate more data than most other types of sensors. For example, an ordinary survey may generate several hundred data points. Over time, tens of thousands of data points must be reduced, compared, plotted, and archived. Slope Indicator's DigiPro2 Software is designed to speed these tasks.

accuracy

Certain highly sensitive electronic inclinometer sensors can achieve an output resolution to 0.0001 degrees - depending on the technology and angle range, it may be limited to 0.01º. An inclinometer sensor's true or absolute accuracy (which is the combined total error), however, is a combination of initial sets of sensor zero offset and sensitivity, sensor linearity, hysteresis, repeatability, and the temperature drifts of zero and sensitivity - electronic inclinometers accuracy can typically range from .01º to ±2º depending on the sensor and situation. Typically in room ambient conditions the accuracy is limited to the sensor linearity specification.

Sensor technology

Tilt sensors and inclinometers generate an artificial horizon and measure angular tilt with respect to this horizon. They are used in cameras, aircraft flight controls, automobile security systems, and speciality switches and are also used for platform leveling, boom angle indication, and in other applications requiring measurement of tilt.

Important specifications to consider when searching for tilt sensors and inclinometers are the tilt angle range and number of axes (which are usually, but not always, orthogonal). The tilt angle range is the range of desired linear output.

Common implementations of tilt sensors and inclinometers are accelerometer, Liquid Capacitive, electrolytic, gas bubble in liquid, and pendulum.

Tilt sensor technology has also been implemented in video games. Yoshi's Universal Gravitation and Kirby Tilt 'n' Tumble are both built around a tilt sensor mechanism, which is built into the cartridge. The PlayStation 3 and Wii game controllers also use tilt as a means to play video games.

Inclinometers are also used in civil engineering, for example to measure the inclination of land to be built upon.

Some inclinometers provide an electronic interface based on CAN (Controller Area Network). In addition, those inclinometers may support the standardized CANopen profile (CiA 410). In this case, these inclinometers are compatible and partly interchangeable.

2-Axis Digital Inclinometer

Traditional spirit levels and pendulum-based digital levels are commonly constrained by (i) single axis (ii) narrow angular tilt measurement range, and (iii) susceptible to cross axis error. However, precision levelling, angle measurement, alignment and surface flatness profiling tasks essentially involve a 2-dimensional plane rather than two independent single-axis objects. The 2-Axis inclinometer utilizing advanced MEMS technology provides simultaneous 2-axis and wide angle measuring range features that the traditional single-axis digital and 'bubble' levels are unable to offer.

2-Axis Digital Inclinometer

Advantages of new 2-Axis digital inclinometer over conventional single-axis leveling instruments:

2-axis technology enables simultaneous 2D (X-Y plane) tilt angles measurement (i.e. pitch & roll), completely eliminates tedious trial-and-error (i.e. going back-and-forth) experienced when using single-axis levels to adjust machine footings to achieve a precise leveling position.

2-axis MEMS driven inclinometers can be digitally compensated and precisely calibrated for non-linearity and operating temperature variation resulting higher angular accuracy and stability performance over wider angular measurement range.

Digital graphical bull’s eye with numerical data and a built-in vibrometer enable machine installer to track alignment in real-time and verify positional stability by comparing machine's leveling profiles before and after setting up, i.e. accountability & quality works.

2-axis MEMS inclinometer effectively eradicates constraints experienced when using conventional single-axis instrument that requires leveling tasks to be conducted one axis at a time with tedious alignment iterations, and the numerical display prevents parallax error when reading ‘bubble’ vial position from a distance.

2-Axis Digital Inclinometer

Applications

Inclinometers are used to monitor subsurface movements and deformations. Typical applications include:

Detecting zones of movement and establish whether movement is constant, accelerating, or responding to remedial measures.

Checking that deformations are within design limits, that struts and anchors are performing as expected, and that adjacent buildings are not affected by ground movements.

Verifying stability of dams, dam abutments, and upstream slopes during and after impoundment.

Monitoring settlement profiles of embankments, foundations, and other structures (horizontal inclinometer).

n-Place Measurement Systems

In-Place Inclinometer Sensors

In-place measurement systems are installed when continuous monitoring is required for construction control or safety.

The in-place system consist of one or more dedicated sensors connected to adata logger. The sensors are positioned to span the zones where deformation is likely to occur.

In-place inclinometer systems generate even more data than portable systems, and often the data must be processed and distributed immediately. Slope Indicator's Atlas web-based monitoring performs this task, automatically processing the readings, checking for alarms, and generating graphs and reports.

Spiral Checking A spiral sensor provides readings that can be used to correct inclinometer data obtained

from spiraled casing. Spiral surveys are recommended when the installation is very deep, when inclinometer readings indicate movement in unlikely directions, or when difficulties were experienced during installation.