Intelligent Pressure Sensor and Can-Bus Communication System

Truck scales are systems developed to measure the weight values when a truck is placed on them. The history of truck scales begins with industrialization, increased flow of goods, and heavy freight transportation. Until the 18th century, goods were manually placed on scales. Since this process was manual, the weights of goods couldn't exceed 500 kg, which was the weight of a common container back then.
With the development and use of mechanical truck scales in the 19th century, it became possible to weigh large loads. From the mid-20th century onwards, electronic scales gradually replaced mechanical weighing machines. The widespread use of load cells based on strain gauges started with the use of these load cells and has formed the technical basis of truck scales since the mid-1990s [1]. Among the studies conducted as an alternative to fixed truck scales, the most common is the development and production of systems by various companies (Vishay, High-Tech Scale, Kimax, reigh weigh, etc.) that use pressure sensors attached to the air suspension bellows [2]. Various products have been developed in this regard, and manufacturers have obtained patents [3-4].
Our company currently produces fixed truck scales consisting of load cells, weighing platform, and an electronic display system installed at the roadside, where trucks can be weighed by driving onto the scale. However, our new product, which will be directly attached to the truck, will weigh the material loaded onto the truck from the moment of loading. It will determine whether the load on the truck's axles complies with legal limits according to highway regulations before the truck hits the road, preventing fines. It will also ensure road safety by preventing the drawbacks of overloading and preventing road damage. In this context, our newly developed product is entirely based on a new product design and development project.
Since the demands from our customers started to come in, we began researching how to measure the load while it is still on the truck. However, considering the limitations of our existing load cells in solving this issue and the fact that a load cell fixed in one place would quickly degrade or cause significant measurement errors during the truck's movement, encountering bumps and vibrations, we postponed our involvement in the project. However, a competitor company in the United States (www.rwls.com) mentioned a sensor attached to the air suspension bellows of trucks, which provided us with a way out. Since we couldn't thoroughly examine the product of this company, we decided to design and develop a pneumatic pressure sensor that would be attached to the compressed air line through trial measurements.
In the scope of our project, we first developed a pneumatic pressure sensor. Subsequently, we developed an electronic display system that processes the data from this pressure sensor to show the measured weight value. Additionally, to remotely monitor and track the measurement data, we developed a CAN-BUS software that interfaces with the vehicle tracking systems present in each truck.
In our TÜBİTAK-supported project, we produced a solution to the need for a "Smart weight measurement system that can be mounted on trucks and trailers" with sensors for weight, angle, acceleration, and temperature, which is not available in similar systems worldwide. The product we developed is designed to be easily attached directly to the air suspension bellows of all trucks, tractors, and trailers with air suspension.
The system, after installation, automatically corrects measurement errors due to road conditions, slope, vehicle acceleration, and ambient temperature changes using angle, acceleration, and temperature sensors. This is the world's first system that compensates for measurement errors caused by road slope, vehicle acceleration and braking-induced acceleration, and temperature changes. Our system, which works in harmony with vehicle tracking systems through the CAN-BUS communication network, will be a highly preferred 100% domestic product, providing remote monitoring, data acquisition, and control of the load on each axle and axle.

Structure and Technological Features of Our Developed System
Our developed system, as part of the R&D project, can be summarized briefly as follows:
- The developed system will be a pneumatic pressure sensor and weight measurement system designed to attach to the air suspension bellows of trucks with air suspension, and it will be applied by our company for the first time in our country.
- The developed pressure sensor will measure with a strain gauge and bridge circuit.
- The developed pressure sensor will be an intelligent system that automatically corrects measurement errors due to road slope, vehicle acceleration, and temperature changes by embedding angle, acceleration, and temperature sensors.
- Our system will work in harmony with vehicle tracking systems through the CAN-BUS communication infrastructure, providing the opportunity to remotely monitor, acquire data, and control the load on each axle and axle.
- Microprocessor, communication, weight measurement, and DAC circuits will be added to the truck and tractor weight measurement system.


Innovative Aspects of Our Developed System Our developed system has many innovative aspects compared to competing products:
- The strain gauge pressure sensor, specially designed to be attached to the compressed air line of the truck's air suspension system, has been developed for the first time in our country.
- The system, equipped with angle sensors, corrects measurement errors on inclined roads, acceleration sensors correct acceleration measurement errors caused by the truck's movement and braking, and temperature sensors correct measurement errors due to external temperature changes and changes in compressed air temperature. It will be introduced to the market as the world's first SMART system.
- Loads on truck axles and suspensions can be read independently with a multi-channel display.
- Coupled with vehicle tracking systems, it will transfer weight data via the CAN-BUS communication network for each axle and axle.

Mechanical Manufacturing of the Truck-mounted Pneumatic Pressure Sensor
In our project, a strain gauge pressure sensor specially designed to be attached to the compressed air line of air suspension bellows used in vehicles carrying both cargo and passengers has been developed, and the prototype has been completed.
The production of a strain gauge pressure sensor has been realized by our company for the first time in Turkey as part of our project. The design was made using AISI 17-4 PH stainless steel to withstand outdoor conditions since trucks would be used in open areas and operate with compressed air at 7
bars. The system's precision and reliability will be proven in the ongoing trial measurements, and it will be delivered to the market as a Turkish product.
The structure of the developed system includes a pneumatic pressure sensor, a microprocessor to process the data obtained from this sensor, an electronic display system to show the measured weight value, and a CAN-BUS software to monitor and track the measurement data remotely.
The entire structure of the system, from the pressure sensor to the display unit and communication software, is designed to work in harmony to provide accurate and reliable weight measurements for trucks and trailers with air suspension.

**Applications of the Truck-mounted Pneumatic Pressure Sensor** The system developed within the scope of the R&D project can be applied to various types of trucks, tractors, and trailers equipped with air suspension systems,
which are widely used in both cargo and passenger transportation.
- **Cargo Trucks:** The system is suitable for all types of cargo trucks with air suspension, including those used in construction, logistics, and transportation of goods.
- **Trailers:** It can be easily mounted on trailers with air suspension, providing accurate weight measurements for various types of trailers used in different industries.
- **Passenger Buses:** The system is applicable to buses with air suspension, ensuring that passenger buses comply with weight regulations for safe transportation.
- **Special Purpose Vehicles:** It can be integrated into special-purpose vehicles with air suspension, such as fire trucks, ambulances, and other specialized vehicles, to monitor weight distribution.


**Advantages of the Truck-mounted Pneumatic Pressure Sensor**

The newly developed truck-mounted pneumatic pressure sensor offers several advantages over traditional weighing methods:

- **Real-time Weight Measurement:** The system provides real-time weight measurements as the material is loaded onto the truck, allowing for immediate compliance with legal weight limits.
- **Prevention of Overloading:** By monitoring the weight distribution on each axle and axle group, the system helps prevent overloading, ensuring road safety and compliance with regulations.
- **Automatic Error Correction:** The system's intelligent design, with embedded angle, acceleration, and temperature sensors, automatically corrects measurement errors caused by road conditions, slope, vehicle acceleration, and temperature changes.
- **Remote Monitoring and Tracking:** Integrated with vehicle tracking systems through the CAN-BUS communication network, the system enables remote monitoring, data acquisition, and control of the load on each axle and axle group.
- **Versatility:** The system can be applied to various types of trucks, trailers, and special-purpose vehicles with air suspension, making it a versatile solution for different industries.
- **Precision and Reliability:** The strain gauge pressure sensor, designed and manufactured by our company, ensures precision and reliability in weight measurements, even in challenging outdoor conditions.


**Conclusion**
The truck-mounted pneumatic pressure sensor developed as part of our R&D project represents a significant advancement in the field of weight measurement for trucks, trailers, and other vehicles with air suspension. Its innovative design, incorporating a strain gauge pressure sensor, angle sensors, acceleration sensors, and temperature sensors, sets it apart as a SMART system capable of providing accurate and reliable weight measurements.
The system's ability to perform real-time weight measurements, prevent overloading, and automatically correct measurement errors enhances road safety, prevents fines, and ensures compliance with legal weight regulations. Additionally, its integration with vehicle tracking systems enables remote monitoring and tracking of weight distribution, contributing to efficient fleet management.
Our commitment to producing a high-quality, domestically developed product is reflected in the precision and reliability of the strain gauge pressure sensor, a first-of-its-kind in Turkey. As we continue with trial measurements and gather feedback from users, we aim to further refine and optimize the system for widespread adoption in various industries.
In summary, our truck-mounted pneumatic pressure sensor stands as a testament to our dedication to innovation and excellence in the field of weighing technology, offering a solution that meets the evolving needs of the transportation and logistics industry.