Microprocessor-based system for roll-down and acceleration tests

A microprocessor-based, road-test system for measuring and recording roll-down and acceleration data has been designed and built. The system provides for rapid testing of vehicles, can be operated by a single individual, and allows detailed data acquisition when required. Digital data storage and output capability allows direct exchange of data with other computers or calculators for data analysis and reduction. System input is distance from a fifth wheel and elapsed time. The microcomputer system records time to the nearest 0.01 second, distance to the nearest foot, and calculates velocity to the nearest 0.1 mile per hour. Data can be stored at specified time, distance, and velocity intervals. Current time, distance, and velocity are displayed on a liquid crystal display panel. A printing calculator prints a summary of the run. Detailed data is stored in RAM and is output to magnetic tape at the end of the run. The tapes are used to obtain plots and as input for data reduction programs that calculate rolling friction and aerodynamic drag. The road-test system has been used to test a number of vehicles. In most of the tests one person drove the vehicle and operated the system.