Role of Bluetooth in automotive applications
Bluetooth in cars:
The new generations of cars will have an increasing number of microcontrollers connected through two or more networks. One advantage of this is that the car can be individually customized via software, another being that to a large extent the car can have self-diagnostic functions. To fully utilize these functions, it is necessary to have two-way communication between the car’s system and production tools, as well as service tools for downloading new parameters and software, and uploading status and diagnostic messages. This production and service tool will be largely based on PC technology. The connection between the car system and the tool is made via a cable, either directly to the CAN bus (Controller Area Network) via a gateway. The cheapest way is to connect the PC directly to the CAN bus by drip line, but this has to be short. According to the CAN standard, it must be less than 39 cm at a bit rate of 1 Mbit/s. Compare to USB and Bluetooth, the mobility and versatility is high-performance Bluetooth.
Bluetooth in car production:
In automobile production, a large amount of software is downloaded as the final step on the production line. This is an application where Bluetooth would be ideal. The Bluetooth base station is connected to the production fieldbus. When the online car connects to the Bluetooth base station, it uploads its serial number. The production computer then downloads the software for this very car via the fieldbus to the base station, which in turn transmits it to the car. However, this is a dedicated use and no Bluetooth units other than those installed in cars should be connected to the cell.
Bluetooth for car service:
A scenario for using Bluetooth could be:
1) When the car enters the service station, its Bluetooth station contacts the main computer of the service station. This has previously exchanged information with the car’s computer via the mobile phone system.
2) The service station main computer alerts the service man assigned to the task and his PC establishes contact with the car and downloads any necessary information.
3) The technician receives the necessary work instructions on his PC. When he maintains the car, he can control and adjust various functions through the PC, for example, lights, windows, climate control, engine parameters, etc. He can also download the latest software versions to any Electronic Control Unit (ECU)
CAN/Bluetooth Basics:
CAN was developed to be a basis for highly reliable communication over a twisted pair of wires that could be applied from very simple tasks to advanced real-time control. To achieve this goal, it is based on the principle that every node in a system simultaneously checks every bit transmitted on the bus. Based on this principle, a number of issues such as bus access, collision detection, data consistency, etc. are elegantly resolved. However, the condition that all nodes see the same bit at the same time requires a controlled waveform delay. This is easily accomplished in a wired system but difficult to achieve in a wireless system. Therefore, any wireless transmission in CAN systems must be done through gateways and Bluetooth offers the best possibilities for this task among the available radio standards.
The ideal Bluetooth concept for diagnostics:
The ideal concept of Bluetooth for diagnosis should display the following qualities:
1 Low cost
2 Performance as needed
3 standards as needed
To achieve these goals, we must have a low-cost, high-performance Bluetooth unit that can be used for any application. So it has to be stripped of everything that not everyone needs, that is, a concept like CAN. It MAY provide the basic functions needed by any controller network, but the remaining required functions must be provided by an additional upper layer protocol. The basic block of Bluetooth must take care of the RF part and the essential part of the baseband protocol which is of little or no interest for any application but essential for the functionality of Bluetooth.
Communication during production:
The use of wireless communication between the vehicle and the production line automation system could open the way to completely new functions in the production process. Depending on the process step, for example during final assembly, the vehicle controller and production line controllers can exchange both product and process status information.
Communication during the service:
Potential in-service applications can easily be derived from the scenario for the production process described above. Wireless communication between the vehicle and a service station computer can be used to exchange status information and service-specific information. This step may be supported by previous data exchange using telecommunications. Wireless communication in combination with a mobile service computer offers optimum flexibility for service personnel.
Advantages and benefits:
The most important advantages of wireless technologies for technical tasks are more or less hidden from the vehicle customer. The advantage of this solution is increased flexibility, modularity and reliability. Although the benefit cannot be directly experienced by customers, it is important to the automotive industry. In addition, the potential of wireless communication at the level of technical tasks between smart devices and control units inside the vehicle, as well as control units and human-machine interfaces in the area surrounding the car, may lead to new functionalities and increased of flexibility during production and service. The benefit to the customer is an increase in reliability. For the product development phases, the increased flexibility is a great benefit. A simplified wiring harness and wireless interfaces are advantages for manufacturing. For service, maintenance and repair, wireless interfaces are advantageous with respect to the disassembly and assembly of parts. In addition, wireless communication opens up possibilities for flexible connections to human-machine interfaces and diagnostic systems. Although, in general, an electronic component for a wireless transmission unit is more expensive than a cable, there are several possibilities to reduce the cost of the product, for example through standardization and reduction of assembly efforts.
Conclusion:
There is a potential for up to hundreds of millions of Bluetooth nodes per year within the vehicle manufacturer market if Bluetooth can be used for real-time control and other technical tasks. For several years, an important trend in vehicle development has been the increase in the number of electrical and electronic systems. Many of these systems have been introduced to offer customer innovations through increased functionality, comfort and safety. Another reason is the partial replacement of mechanical components by electrical components or their integration into mechatronic systems.
References
1) Bluetooth in automotive applications
Lars-Berno Fredriksson, KVASER AB
2) The potential of Bluetooth in automotive applications
Horst Wunderlich and Martin Schwab, DaimlerChrysler R&T, Germany Lars-Berno Fredriksson, Kvaser AB, Sweden
3) Bluetooth wireless technology optimization
as the ideal interface for car diagnostics -Lars-Berno Fredriksson, Kvaser AB, Sweden