On-board sensors for work-site vehicles. SAcS anti-rollover alarm system for earthmoving equipment

The paper describes the development of the prototype of an electronic instrument1 to be used on board work- site vehicles that operate on rough and uneven land with potholes and dips, with the aim of conducting a dynamic check of the rollover risk determined by exceeding the threshold limit of the amplitude of the angle formed by the gravitational vector with the instantaneous normal angle defined by the points where the vehicle wheels make contact with the ground. The product is one of the results of the Smart Yard research: Industry 4.0 Production Process2 and is a pilot example of the testing of sensors aimed at increasing safety in the use of the equipment. Il contributo illustra lo sviluppo di un prototipo di strumento elettronico da impiegare a bordo di mezzi di cantiere che operano in terreni sconnessi e impervi e in concomitanza di buche e avvalli, finalizzato alla verifica dinamica del rischio di ribaltamento determinato dal superamento della soglia limite dell’ampiezza dell’angolo formato dal vettore gravitazionale con quello normale istantaneo definito dai punti di con- tatto delle ruote del veicolo con il terreno. Il prodotto rappresenta uno dei risultati della ricerca Smart Yard: Industry 4.0 Production Process2 e si configura quale esempio pilota di sperimentazione di sensoristica volta a incrementare la sicurezza di utilizzo dei macchinari.


INTRODUCTION
An observation made by INAIL 3 on the dynamics of workplace accidents caused by vehicle rollover highlighted that earthmoving equipment was responsible for 14.7% of accidents.
Rollover occurs when the lateral tilt is such that the weight of the vehicle is thrown off its transverse axis of rotation.
This mostly occurs in the case of heavy duty activities, work contexts marked by stress, specific ground conditions and the use of worn out equipment.
The risk could be mitigated by equipping vehicles with an instrument capable of measuring the tilt and warning of the threat.As regards the on-board intelligence of work-site vehicles, there are solutions that control their horizontal stability by displaying slope values on analogue or digital devices, however they require the attention of workers who are at the same time already engaged in rather complex and risky activities.
The paper describes the development of the prototype of an electronic instrument 1 to be used on board worksite vehicles that operate on rough and uneven land with potholes and dips, with the aim of conducting a dynamic check of the rollover risk determined by exceeding the threshold limit of the amplitude of the angle formed by the gravitational vector with the instantaneous normal angle defined by the points where the vehicle wheels make contact with the ground.The product is one of the results of the Smart Yard research: Industry 4.0 Production Process 2 and is a pilot example of the testing of sensors aimed at increasing safety in the use of the equipment.
The sensor has a micro mechanical device encapsulated in a small electronic device within which orthogonal displacements of small suspended masses are produced by means of elastic micro-beams.The electronic control systems, through the accelerometer, record changes in the vehicle's tilt with respect to the horizontal plane, and when the risk limit values are reached a series of optical and acoustic alarm signals are activated.A detailed design of the instrument was drawn up on the basis of which an initial prototype (Fig. 1) was created which, despite functioning correctly, had some critical issues.The power level of the acoustic signals was not effectively calibrated for the noise level of the operating contexts; the materials used meant it was not sufficiently robust during operation; the fact that the operator could deactivate it during operation did not protect their safety and security, and the display of the warning values was not immediate.It was therefore necessary to: strengthen the acoustic emissions of the signals with the opportunity to provide differentiated intensities according to the severity of the danger and in highly critical situations activate the blue colour in all LEDs; place the components inside to minimise material discontinuity; restrict the adjustability of the display in favour of a fixed reading angle by reducing the mobile components and simplifying the implementation; divide the instrument into two distinct parts, one that could be managed by the operator and one that was inaccessible; correct software malfunctions in the microcontroller device by amending the source code to avoid slowing down the display and simplify the language.The revision process led to updates at structural, By providing advance warning of potentially critical conditions, the hypothesized electronic device is able to measure the rollover risk of earthmoving equipment along its travel path and emit sound and light to signal its gradual tilt in order to induce the operator to activate the appropriate self-protection measures and alter the path or, if necessary, stop the vehicle.

THE ANTI-ROLLOVER ALARM SYSTEM
The SAcS inclinometer 4 , designed to prevent the lateral rollover of work vehicles operating on land with slopes that are predominantly transverse to the direction of travel, consists of an integrated system of safety components.It has threefold functionality: it uses a binary detection system to record the slope determined by the tilt of the axle with respect to the horizontal plane; it emits light and sound alarm signals when specific threshold values are reached, attracting the operator's attention; it prompts the activation of further safety mechanisms such as active and passive protection devices, the interruption of electrical contacts, circuit shutdown, and the release of mechanical supports, etc..The device is operated by a tri-axial capacitive accelerometer based on MEMS 5 technology.This is a very small and inexpensive inertial microelectromechanical sensor that can be installed directly on a PCB 6 , which studies the dynamic principles of bodies in order to discover their causes and is capable of measuring the linear and angular acceleration of their displacement in space.Accelerometers are used both to detect static gravitational acceleration, as tilt sensors to determine the angle of deviation from the vertical plane of the units that accommodate them, and to detect dynamic acceleration, as inertial measurement indicators of their speed and detectors of vibration, impact or shock.In this case, it is used to estimate the change in electrical capacity according to the change in movement within a circuit formed of an electrical resistor and a capacitor connected by a voltage generator 7 , exploiting the positioning of a weight installed on springs attached at one end to the weight itself and at the other to the armatures of the device8 .The system is fitted with a switch which, by regulating the charging and discharging processes, is able to control the intensity of the electricity on the armatures and the current within the circuit.
journal valori e valutazioni No. 31 -2022 On-board sensors for work-site vehicles.SAcS anti-rollover alarm system for earthmoving equipment ... journal valori e valutazioni No. 31 -2022 105 operational and software level.As the sensor is inertial, the functional scope was also extended which, together with its use in rollover dynamics, included additional performance features such as determination of the position, time-of-use estimation, etc.

DEVICE COMPONENTS AND OPERATING PRINCIPLE
The final version of the system has two separate, networked elements consisting of a terminal that the operator can switch on and off and a non-manoeuvrable control unit with access to a power line that is activated when the vehicle starts up and can block it if activation of the terminal is not detected when it is used (Fig. 2).
The control unit was later replaced with an application that manages communication with the terminal via wireless Bluetooth.
The terminal consists of a metal tube (Ø 50 mm x 500) that houses within it, arranged on a frame and protected from external agents, the electronic and micro-control components and the low-power, high-resolution triaxial accelerometer used to accurately read the angular tilt of the gravity vector with respect to the horizontal plane (Fig. 3).
The element has a 7-segment central display 9 at the front and side light units.By means of the impulse received from the microcontroller that acquires the value of the angular variation from the accelerometer, the display uses an alphanumeric code to reveal in real time the vehicle's tilt value and, by means of a calibration log, activates the light indicators with differentiated lights in sequence, coordinated with the acoustic signalling system equipped with an audio amplifier, generating progressive emissions that interpret the significance of the danger.
The sensor translates the energy into electrical signals proportional to the instantaneous acceleration of the body, reproducing the coded and shared colours that classify the probability of the risk occurring.Green indicates that there are no major phenomena, yellow advises caution and red indicates the severity of the criticality.The upper part of the display also houses an additional flashing blue indicator light, which is activated at the same time as the red one and when a more acute two-tone sound is emitted, indicating that maximum concentration is required on the vehicle (Fig. 4).The different colours, which convey the magnitude of the impact, clearly communicate the warning and suggest the self-protection behavioural patterns to be assumed in order to ensure maximum safety.
The magnitude of the danger that prompts activation of the various acoustic and visual indicators can be altered through programming, which involves an encrypted operating sequence performed by using a button located on the rear of the display.The selector button sends the input (pull-up) to the microcontroller which assigns different degrees of intensity to the maximum tilt values, depending on the use parameters, the gauge, the specificity and state of efficiency of the vehicle, the consistency of the ground and the condition of the soil where the wheels are moving (Fig. 5).At the top of the terminal, on either side of the display compartment, there are cooling grids and speakers; the on/off switch and the USB port for connecting it to the charging station are found at the back.The tube, fitted with two magnetic neodymium mounts 9 The display is inserted into the metal tube at a tilt angle of 30° to the vertical to give the operator an optimum view   at the bottom, is removable and can be applied to any metal surface.It is fixed on the dashboard in line with the transverse axis of the vehicle, at the most appropriate height so that the operator can obtain information immediately without distracting visual attention from the trajectory.In the case of non-metallic surfaces, stabilisation is achieved by mechanically anchored brackets.
The system, powered by rechargeable batteries also positioned internally where the electronic components and the alarm sound amplifier are located, is activated automatically at the same time as the machine is operated and shows the value of the transverse angle in sexagesimal degrees on the display (Fig. 6).When not in use, or when the vehicle is perfectly horizontal (± 2°), the terminal automatically goes into stand-by and does not consume any power.The control unit, made up of a casing with a sealed top cover, acts as a bridge between the terminal and the active drive system and is electrically powered.At the front, coinciding with the cover, there is a large backlit LCD display while the software processor, relay, wireless transmitter and calibration button are housed inside (Fig. 7).
The casing receives data on the level of tilt from the terminal, remotely records the position and speed of the journal valori e valutazioni No. 31 -2022  On-board sensors for work-site vehicles.SAcS anti-rollover alarm system for earthmoving equipment ... journal valori e valutazioni No. 31 -2022 107 machine and, in hazardous situations, produces impulses that recommend activation of the appropriate safety measures while at the same time alerting the personnel responsible for protecting the health and safety of workers.The instrument is also capable of preventing the machine's ignition if the terminal is switched off or incorrectly positioned.The on-board installation using safety screws and the configuration, which involves opening the device by removing the cover, can only be carried out by qualified personnel and involves an initial action connected with starting up the vehicle and switching on the terminal and a subsequent check of the communication process between the terminal and the control unit.If communication is standard, the technician proceeds with the calibration by setting the attention parameters according to the type of vehicle and the specific context and then carefully closes the casing.(Fig. 8) The programmed values remain in the memory until the next calibration procedure.

TESTING OF AN APPLICATION
In order to make wider use of the information transmitted by the terminal and allow the Safety Coordinator to have control, even remotely, over the actions of the vehicle operator during the Execution phase, the possibility of using the Bluetooth wireless communication system was assessed.To this end, an application capable of dialoguing with the terminal via Bluetooth protocol was developed, for use in the Android environment, in full screen mode.In the new   In these circumstances, by downloading the application that updates the values as the transverse tilt of the machine changes, the operator can use a mobile phone which, with respect to the terminal, provides effects such as vibrations, pulses, colours and customisable sounds and determines the position, temperature and speed components and, with appropriate algorithms in place, it can examine further variables that help to provide greater reliability in estimating the risk.
The screen «landscape» format also displays the information more clearly (Fig. 11).

THE PROTOTYPE
In order to check the technical and economic feasibility, on the basis of the project developed and using a suitable market survey, a estimate was made to establish the presumed economic value of the device with a view to determining the price to be set as a basis for the tender in order to identify the entity to be entrusted with manufacturing the prototypes.
Bidders were asked to produce two prototypes, one in steel (Ø 50 mm, ≠15/10 mm, length 590 mm) and one in aluminium (Ø 60 mm, ≠2 mm, length 600 mm), cut and machined with the appropriate openings on the casing surface for the display of the light signalling elements  Smartphones and tablets, by taking advantage of inertial sensors (accelerometer, gyroscope and position), can also replace the terminal, leading to benefits in terms of cost which would only refer to purchasing the support for them to be fixed on board.
They can be very useful in vehicles where the dimensions of the metal tube are excessive and installation difficult (Fig. 10).
On-board sensors for work-site vehicles.SAcS anti-rollover alarm system for earthmoving equipment ... journal valori e valutazioni No. 31 -2022 109 magnets suitable for attachment to any metal surface subjected to frequent mechanical stress (Fig. 12).By calculating the constituent components indicated in the design documentation of the device the total value of the two models was quantified as €5,800.00(Fig. 13).Being experimental samples, any further work not contemplated but that might be needed for they to work could be accounted for on the basis of an hourly cost of €55.00.In compliance with the principle of rotation, economic operators based not too far away, with appropriate skills and operational abilities, with previous experience in the sector and suitable equipment were invited to participate in the tender.The contractor selected from the bids received was the one that gave the largest discount on the tender amount, which proposed a discount of 5% for a total amount of €5,510.00.The works were carried out in observant compliance with the specific instructions set out in the design documentation given to the bidders, whose executive level of detail justified the awarding of the contract to the lowest price.On-board sensors for work-site vehicles.SAcS anti-rollover alarm system for earthmoving equipment ... results from which twenty patents 10 , considered most appropriately comparable, were selected in order to explore their attributes corresponding to the keywords defined and observe their similarities with the developed project.The patents with the highest number of shared features were 3: Vehicle Rollover Safety System 11 ; Dynamic Rollover Protection System 12 and System and Method for the Detection of Vehicle Rollover Conditions 13 (Fig. 14).The first is a tool that, by means of the collaboration between sensors with associated microprocessor and central controller, detects the vehicle rollover risks, communicates them to operators by means of acoustic signals, suggesting steering correction and in the event of an accident, by means of a radio communications transceiver to a call center, activates the necessary emergency assistance.The second, formed by a group of sensors and a warning system, informs of the imminence of a rollover, allows the driver to take corrective action and updates the information during and after the danger.The third, uses sensors mounted to the vehicle frame which, together with the suspension system, detect its lateral acceleration to determine the load transfer ratio of an actual tilt moment compared to the maximum tilt moment and to calculate the effective center of gravity height and reports the acquired values to the operator by means of a display coupled to the system.FHowever, the comparison did not reveal portable systems fitted with a magnetic support, with plug-andplay operation, that can be updated, powered by rechargeable batteries and used for different purposes.Digitally readable systems also were found that display the goniometric value in degrees or radians and that replace spirit level, pendulum level, flexible tube level or other work-site instruments, as well as equipment capable of reading the amplitude of the body's tilt angle with respect to the horizontal plane used on board offroad cars or as equipment in the nautical sector.However, the communication conveyed by such devices is not progressive and the signals resort to light or sound emissions without exploiting specific codes or languages.The SAcS digital inclinometer is an integrated system of functions and components that records the transverse tilt angle of a vehicle in operation and, through the use of accelerometers, goniometric detectors and software processors (such as Arduino), it is able to generate a series of simultaneous optical light alarm signals, as well as a two-tone siren, which prompt the operator to activate safety measures in order to counteract the risk of rollover.The instrument activates autonomously as a function of an increase in the stabilising moment with respect to the rollover moment in the dynamics of masses in motion.For these specific functions, the product is suitable for use with accident prevention purposes.The analysis conducted showed that there is no slope detection device on the market integrated with an alarm signal system that aims to have the operator activate self-monitoring and risk assessment processes, therefore SAcS was found to be an original solution compatible with the technological and economic feasibility and consistent with the expected application.
journal valori e valutazioni No. 31 -2022 111 On-board sensors for work-site vehicles.SAcS anti-rollover alarm system for earthmoving equipment ...

Figure 2 -
Figure 2 -Terminal and Control Unit on board the vehicle.

Figure 4 -
Figure 4 -Operation of the Terminal.

Figure 6 -
Figure 6 -Constituent components of the Terminal.

Figure 7 -
Figure 7 -Constituent components of the Control Unit.Figure 8 -Control Unit.

Figure 8 -
Figure 7 -Constituent components of the Control Unit.Figure 8 -Control Unit.

Figure 11 -
Figure 11 -Android device as the Terminal: application interface.

Figure 12 -
Figure 12 -Design documentation as a basis for the tender .
12. ES 2541376 B2 -"Electronic device and method of protection against overturning for agricultural, forestry and public works vehicles", htps://patents.google.Safety accident sensing device for agricultural machine and system for spreading situation automatically using the same", https://patents .google.com/patent/KR20180031147A.Shared keywords 7 of 16 for an overall consistency of 43.75%.20.EP 0942839 A1 -"System and method for the detection of vehicle rollover conditions", https://patents.google.com/patent/EP0942839A1/en. Shared keywords 11 of 16 for an overall consistency of 68.75%.