Mumbai University > Electronics Engineering > Sem 7 > Embedded System Design

Marks: 20 Marks

Year: May 2016

Hardware block diagram

1. The heart of the system is CPU which could be a modern day application processor. This unit integrates to all other sub systems of the car like the engine, braking systems, electronics, etc. It also monitors a number of sensors so as to sense the environment.

2. The CPU interacts with the human using the front panel. The front panel consists of a display which could be a Graphics LCD. It also has number of buttons for starting, stopping, setting different parameters like speed, pausing and resuming the given route. All the alphanumerical inputs are given using the keypad.

3. The car has the knowledge of its current location through the GPS (Global positioning system) present on-board.

4. Four radars having a wide viewing angle are present on all the four sides of the cars. The viewing angle is selected such that it can capture information pertaining to obstacles, pedestrians and other vehicles on all four sides of the car. The radar is selected such that it can also detect moving objects.
5. Wheel encoders are placed on the two rear wheels of the car. These encoders help in determining the distance the car has moved. Two such encoders and used to reduce errors.
6. A 360o LASER is placed on top of the car. This gathers raw information about all the objects present around. This raw information along with the information from the radars are used to find the presence of objects around the car.
7. The steering control unit is used to control the direction of the car.
8. The braking control unit is used to monitor the speed of the car.
9. Automotive electronics control unit are used to turn-on/off the car’s headlight, backlight etc. in case of insufficient illumination, while giving signals to vehicles around.
10. Other subsystems control unit monitors the fuel tank, car battery’s voltage, temperature of the engine.

System working model (FSM):

1. The CPU acquires the current location from the GPS till it receives an error free response.
2. On receiving the location it asks the user to enter the destination through the HMI interface provided on the front panel.
3. The system then asks the user to set the maximum speed at which the route must be traversed.
4. The system then displays all the parameters and asks form confirmation. If the user doesn’t confirm then the system goes to the first state.
5. On confirming the system scans and processes information from all the sensors to get an idea of the obstacles. If obstacles are present then engine doesn’t start.
6. The system accelerates and periodically scans the sensors. If obstacles are present the car decelerates or stops depending on the type of the obstacle.
7. The system checks for speed and decelerates if the speed is too high. Other checking for direction, fuel etc. can also be done at this stage.
8. Finally the system checks if the destination has been reached, if so then it stops the engine and returns to the first state else it continues accelerating and checking the sensors.

Software architecture/ modules:

1. The drivers are low level entities. These blocks help in interfacing CPU to different peripherals present in the system. They contain implementations of different protocols required to interface the external devices. The various drivers include the display driver, GPS receiver driver, drivers for sensors, drivers for steering, braking and engine control, etc.
2. Functions are a level above the driver and consist of methods used for accessing the drivers. There are different functions for displaying using the Graphics LCD, Functions for acquiring the user data using the Keypad/HMI. Functions for actuating the control systems.
3. The modules help in final application development. They help in integrating the functions for perform different tasks together. For e.g. a module can be defined for integrating all the car’s subsystem like engine control, steering and braking control, fuel monitoring, engine temperature control.