How tilt sensors ensure stability of platforms, lifts and cranes

Anyone who works on fire ladders, lifting platforms, window-cleaning lifts or regular lifts wants to be sure that the surface remains steadily horizontal. On forklift trucks for example, monitoring the boom and fork angle is of critical importance. Steadiness is an important factor in numerous applications. Creating products for those types of situations is one of elobau's strengths.

Mercury switches are a thing of the distant past

Tilt sensors have already been on the market for many years, but only up until recently, they were mainly implemented with mercury contacts. For each axis (X- and/or Y-axis), it was possible to have up to six contacts, and the switching points could be adjusted individually in a number of different degrees. In most cases, the digital signals were connected through a logical "and" function and output via two relay outputs. This mode of operation worked for quite a while, but was ultimately not an environmentally conscious approach. Besides, people started questioning the negative health effects that the prolonged exposure to mercury was causing.

Due to growing environmental awareness and a changing customer desire for mercury-free products, companies such as elobau have started looking for new approaches that eliminate mercury usage. A few years ago, elobau presented tilt sensors from the N1 and N2 series, which completely take over the functionalities of the previously used mercury switches and even offer additional options. The N3, N4, and N5 series are the more recent models and can be even more versatile.

The old mechanical principle was reliable, but since mechanical parts had to be manufactured and assembled - and obviously require a certain amount of maintenance - the effort was relatively high. That is why elobau, after exploring the market, has discovered the MEMS principle. The MEMS principle lays the foundation for the current sensors from the N3, N4, and N5 series.

The most important advantages of all these new tilt sensors are the absence of harmful mercury and the free choice of output signals. These sensors simply work according to a non-contact measurement principle: a magnet, which is mounted in the pivot point of a pendulum, moves around a Hall sensor. The position is evaluated and then converted by the sensor into the desired output signal.

Tilt sensors with various output options

elobau's tilt sensors offer various implementation options. While a digital output signal was the only possible option with the previous mercury alternative, it is now possible to choose between digital and analogue signals for all series. The analogue signals are available in both a current and a voltage output (4 to 20mA or 0.5 to 4.5V). In the case of digital signals, relays or transistors are activated with a maximum switching power of 60V (1A, 30W/VA). To prevent false alarms caused by dangerous vibrations, the output signals can also be provided with a time delay, whereby signals are first compared with each other.

Michael Hetzer, CEO of elobau, shares his view on the current market: "Safety awareness is increasing, and therefore more and more redundant solutions are needed. That is why, from the very start, we have paid attention to redundancy in our new sensors. This means that two completely separate circuits can be installed with two Hall elements and two microcontrollers, which are connected on the output side to relays or transistors."

The connection of the individual contacts is variable. Michael Hetzer explains: "In safety technology, it is common to connect the contacts as a logical "and", but the option of a logical "or" is also available. Another possible variant is to output the signals separately for each switching angle."

First-generation mercury-free tilt sensors from elobau switch in steps of 0.5 degrees from a total angular range of +/- 2 degrees to +/- 15 degrees. Both single axis versions and double axis versions are available. It is particularly easy to place the elobau tilt sensors in the 0 degree position.

Setting the zero position of our tilt sensors is easy. The sensors from the N3 and N4 series, which can control an angle range of +/- 60 degrees, are pre-delivered with a zero position. They can be reset and calibrated by the user via an infrared remote control. With the remote-control device, you are able to change and renew the zero position at any time. This is a particularly significant advantage for use in difficult conditions and hard to reach positions.

Because the elobau system offers different sensors and many configuration options, elobau will remain in close contact with the user from the very beginning, where and when all wishes can be made known. Accordingly, the tilt sensor is pre-configured.

Lift sensor with integrated CAN electronics

The all-new tilt sensor from the N5 series is available with a CAN Interface. The interface is available in either CANopen or J1939 protocol (according to ISO 11898). The measurements in the N5 are made in the same way as in all other elobau series, via MEMS technology, which has proven to be a very reliable sensor for demanding applications in industry and industrial vehicles.

The double axis version has a measuring range of 180 degrees per axis. In the single axis variant, this range doubles to 360 degrees. In addition, a maximum of eight switching points can be defined, and of course, you can have the output with a delay. The neutral position can be calibrated during operation via the CANopen protocol, creating entirely new application options. Manual calibration via infrared remote control is also available for both protocol variants. The mounting of the sensor is simplified by the flat and symmetrical housing design. Also, a redundant measurement can be realised by a direct sensor on sensor mounting.

The electronics are completely sealed, classified in accordance with IP67. A working temperature of -40 to + 85degC and the required 9-32V power supply are designed for use in vehicles such as forklifts, agricultural vehicles, and construction machinery.

CAN in / CAN out

The N5 sensor is now available with CAN in / CAN out. This is a variant that is 100 per cent identical to the previous N5 with the difference that it has as an option to choose two M12's as connectors on the output to loop the CAN signal. Thus, multiple tilt sensors can now be connected without additional components.

Two M12 connectors on one sensor have the advantage that no additional Y/T connectors need be used to loop through the CAN signal. Any additional component is potentially a source of interference that we want to avoid. Furthermore, this technology also simplifies handling and assembly, since fewer components are required. It also means that not every sensor has to be individually wired to the controller. This leads to direct and significant savings in time and money.

Angle sensors also use the Hall sensor principle

The principle of the new tilt sensors - the Hall sensor enclosed by a magnet - has been used by elobau for some time now with angle sensors too. These components also monitor a moving axis and transmit the position signals. The possible angle range in certain designs is up to 360 degrees. The signal is generated in the Hall chip, and three fixed points are programmed by elobau in the electronics: start and end angle, and zero point.

In the case of angle sensors, an analogue signal appears as an output because they are not about a critical angle, but about a continuous output signal. This can be offered in the form of a current or voltage, but can also take the shape of a ratiometric signal.

Accelerate without mechanical transmission

The classic application of angle sensors is the so-called "drive by wir", in which the mechanical transmission of the gas, clutch, or brake pedal is replaced by such a sensor; however, the automotive industry is not the only business that uses such sensors. Angle sensors are also used in textile machines to monitor "dancers'. Even with the automatic peeling of tree logs, these sensors play an important role: with their help, the circumference of the tree is measured continuously. Based on the measured result, the saws are set in such a way that not too much valuable wood is removed.

When it comes to angle sensors, elobau distinguishes between the types 424A and 424R. The newer 424R sensors offer the advantage of an optional redundant design. In addition, an active CAN signal can be generated directly in the device to be connected directly to a CAN bus.

These are some application examples:

Container spreaders: In this case, the lifting block of a container spreader is equipped with a tilt sensor with analogue output that can adjust the control of the spreader very quickly in case of an imbalance (due to disproportionate weight distribution in the container) and ensures that the load is safely brought back into balance. By using a CANopen connection, this tilt sensor can be connected directly to the CAN control by means of a standard M12 connector.

Aerial platforms: The many manufacturers of truck-mounted aerial platforms also know how to find and use the tilt sensors from elobau. They use these sensors to monitor the slope of the basket so that the lifting platforms are safe workplaces.

Forklift truck: You will also find an elobau tilt sensor on the boom of most well-known forklift trucks. This sensor monitors the slope of the fork and converts it into an analogue signal so that the driver always knows the slope of the load.

The tilt sensors from elobau are characterised by a very robust and flat housing and are accurate and contactless. They are also able to withstand powerful shocks and vibrations. This makes the sensors suitable for use in the most demanding and harsh environments.

In addition to a standard sensor package, elobau develops and produces exclusive options specially tailored to the wishes and requirements of the customer. This is done in close collaboration with the customer to develop the right device.

Follow the link for further information abiut elobau's tilt sensors.