Microcontrollers and their functions

1. Microcontrollers and their functions

Microcontrollers in AVAS are settled by territorial criterion, i.e. in places where there is maximum number of sensors of systems and executing mechanisms (example in Application 4.1, Application 4.2). One microcontroller can serve sensors and executing mechanisms of different systems by the principle of its proximity to an object of control.

Connection of units in a ubiquitous control system takes place in a common information window. Information window contains all data about the current state of vehicle units and systems. The structure and contents of the window depends on the set of systems installed in a particular vehicle. The functioning of the network is shown in Application 9. The maximum capacity of the system allows to connect up to 1280 sensors and executing mechanisms.

Functions of a microcontroller:

• processes data from connected to it sensors in order to form information window;
• controls connected to it executing mechanisms using shared information window;
• implements functions of a computational node in a common computational network of an automobile. Such distributed computational network executes vehicle control tasks.

One microcontroller serves up to 10 sensors and executing mechanisms. Only one type of microcontroller is used in AVAS; it is directly connected to the vehicle power cable in the voltage range from 5 to 75 volts.

2. Computing environment

The network solution used in the AVAS technology allows to achieve a nonlinear growth of computing capacity of the entire network. Large information processing capacity is necessary for solving a number of vehicle control tasks simultaneously. Figure 1 shows graphs of dependence of a total network computing capacity (number of operations per second) on the number of connected to the network identical microcontrollers.

Figure 1

Graph 1 is a standard network with a “task—microcontroller” distribution (linear dependence). Graph 2 is a network with an optimal distribution of tasks between microcontrollers (exponential dependence). Graph 3 is a maximum computing capacity.

For instance, for creating AVAS-network computing capacity of 100 MIPS 22 microcontrollers with V=5 MIPS are needed. In this case AVAS computing environment executes all options of a microcontroller’s peripheral set of this family. AVAS allows to engage “vacant” network computing capacity with control tasks. This increases network efficiency while reducing costs on communication and data exchange between vehicle units.

Value of such solution:

• Vehicle system can be customized and configured by IT products. The problem of designing and modifying different vehicle systems is simplified;
• Vehicle systems can be united with each other leading to cost reduction. An example of the solution ABS+ESP+ECU+… in Application 5;
• Reliability of the system is increased due to lowering of the number of its elements, single-type electronic components with a possibility of doubling and transfer of functions, IT solutions for increase of reliability provided in AVAS;

Electronic solutions in the AVAS technology allow to utilize the capacity of microcontrollers to the full extent and obtain technical advantages in vehicle systems. AVAS provides the synergy of systems and creates adaptive environment in an automobile on the basis of modern electronic components.

3. Software for the implementation of the network solution. Vehicle operating system. Connection of systems with CAN, LIN protocols into the AVAS network

AVAS software solves a number of tasks:

• Forms a distributed computing network in an automobile;
• Provides the functioning of vehicle control programs in a network of microcontrollers;
• Adjusts, downloads and changes the structure of a network of microcontrollers;
• Operating system adapts control tasks to a flexible computing environment;
• Operating system allows to change the structure and characteristics of a computing environment for the implementation of tasks of different complexity classes;
• Eliminates conflicting situations between several tasks in an automobile;
• Software allows to connect into the AVAS network vehicle systems with protocols CAN, LIN, etc. as individual units.

4. Synchronous circular communication channel

Synchronous circular communication channel is used in the AVAS technology. The channel provides the synchronization of the transferred data to a fixed time-scale which is common for all control tasks.

5. AVAS communication protocol

AVAS communication protocol needs the master unit for synchronization of the communication channel and forming of time-scale. Unlike in CAN protocol, addressing and interchange-controlling information is not transferred in each transfer cycle. Due to this, information density of the channel trebles compared to CAN (Application 8).

AVAS protocol capacity allows to transfer information at lower data transfer speed. Such solution decreases the cost of transmission of one byte of data.

6. The technology of data transfer through the power cable

Control and power supply of vehicle units is implemented through a single channel—a power cable. This provides technical simplification of vehicle systems and achievement of economic advantages. The technology allows for a stable functioning of communication channel under high level of hindrances. Losses of the data transfer speed from hindrances are approximately 100 times lower than, for instance, in CAN protocol (experimental data).

7. The technology of “information condensing”

AVAS implies the technology that increases data transfer speed without increasing the signal transmission frequency. The technology increases the speed of data transfer 4 times in comparison with traditional methods which use 2 conditions of physical communication channel (0 and 1). The transfer method is similar to communication on orthogonal frequencies. A set of technical solutions allows to build a reliable and cheap communication system.

8. The technology of forming program shells for vehicles

A program shell is an integrated set of programs for the implementation of all vehicle functions. This is a set of programs for functioning of control loops of vehicle systems according to certain algorithms. A program shell enables functional integration of all vehicle systems and regard an automobile as a single whole.

The technology of forming program shells includes vehicle description as a set of ;“functional units” and programs of their joint operation. “Functional units” in this technology are virtual objects. Such approach allows for prompt creation with minimal costs of a large number of program shells. AVAS technology gives an opportunity to utilize a variety of program shells in one automobile, thus characteristics and functions of the latter can be changed in a wide range.