Functional Description

This project is intended to be a practical use of electronics on the Formula SAE car designed in conjunction with the Mechanical Engineering Department. The Formula team expressed the need for the ability to measure 0-60 mph acceleration times of the car. This could be implemented by placing magnetic sensors with two magnets 180° apart from each other at the axles. As the magnets pass over one another, electrical pulses are generated which can be processed by a microcontroller. Optical sensors are also being considered for this application. The intent of the calculations performed is to either display on the LCD or stored for downloading at a later time.

A tachometer other than a mechanical - analog unit will be needed. It should be noted that the engine control computer purchased by the ME department has a tachometer output. This will be examined further, however, an electronic tachometer will most likely be developed. The engine speed signal can be taken from the distributor, which will produce pulses to be processed by the microcontroller. The engine speed can then be displayed on the LCD.

It is also useful to find the engaged transmission gear. Since a motorcycle engine is used for this application, it is sometimes difficult to determine if the transmission is in neutral or in a certain gear. Under racing conditions, a quicker method than currently implemented is needed to determine engaged gear. Options for transmission gear sensors will be explored. If a direct method of obtaining this information is not found, wheel rotation speed and engine speed in conjunction with transmission gear ratios can be used to calculate the gear engaged. Wheel rotation speed and engine speed signals will be present as a result of previous processing. This step will be taking those measurements to further calculation.

Information gathered and calculated can be displayed on a LCD display interfaced with a microcontroller. The gear engaged could also be displayed in a sequential LED display. Options will be examined. Figure 1 shows the basic block diagram of system inputs and outputs.

Description of Inputs and Outputs

INPUTS

Wheel Rotation Sensors	Magnetic or optical sensors placed on the rear axles to measure speed of rotation. For measurement of 0-60 mph acceleration times, only one sensor is needed. However, to detect wheel slippage, two are used, one on each axle.
Engine Speed Sensor	Signal taken from distributor so engine speed (RPMs) can be measured and displayed on a tachometer.
Transmission Gear Sensor	Possibly implemented. Methods of detection to be examined. If no direct acquisition can be obtained, wheel rotation, engine speed, and gear ratios can be used.
User Control Interface	A 12-digit keypad interfaced with a microcontroller allowing the user to enter a desired acceleration measurement to a certain speed. For example, the user can enter 0-20 mph measurement or 0-60 depending on the application.

OUTPUTS

LCD (EL) Display	Interfaced with a microcontroller. Displays all information acquired or calculated about acceleration time, engine speed in RPMs, and gear engaged.
LED Indicators	Possibly implemented. Displays gear engaged in an LED sequence to cut down on weight of the system.

View Basic Block Diagram of System