WYD-A portable brake performance tester I. Overview WYD-A portable braking performance tester, is my company developed a handheld intelligent tester. Uses a 32-bit embedded systems arm, its intelligent design, making it easy to operate. The instrument developed in accordance with the national mandatory standards GB7258-2004 "safe operation of motor vehicle technology," Road Test braking performance test requirements applicable to motor vehicle accidents braking performance testing and exploration. The instrument uses 240 * 128 large-screen LCD, character tips, you can display a number of test data, curves, clear and intuitive. Test project using menu-driven operation, easy to use, and automatic storage of test results after the test data are available for viewing analysis. Is the automobile manufacturing industry, forensic, automotive repair industry and automotive testing, research departments ideal test equipment. System is equipped with a standard RS232 interface, can be connected with an external printer for convenient test results and test data dynamic curve print out the test results can also be sent to other devices or computers, or be controlled by other host computers, flexible constitution online testing system. Machine with portable design, compact, equipped with powerful magnets on the external sensor, easy to install, but also for testing on small space vehicles. The instrument can enter the license plate number and 7-digit postcode of the word. The two methods can be used to test the instrument, especially for large vehicles, steam train road test detection. ? Second, the main technical parameters and performance indicators built-in power:? DC9.6v (1.2v 1200mAH NiMH batteries 8) standard 9-pin RS232 interface. (3 feet signal output, 2 feet signal input, 5 feet signals). 9600 baud, 8 data bits, 1 stop bit and no parity. Specific data see attached instructions. ? Dimensions: 205 X 145 X 55 mm Weight:? 1 kg (including internal battery). ? Measuring range: Acceleration: ≤ ± 1.5g Time: ≤10s Resolution:? Acceleration: 0.01m / s2 Speed: 0.01km / h time: 0.01s Distance: 0.01m Accuracy:? 2.0 Third, test items 1, Brake muzzle velocity (v0) unit: km / h 2, the braking distance (s) Unit: m 3, Coordinated Universal Time (t ') Unit: s 4, maximum deceleration (Gmax) Unit: m / s2 5, the average reduction Speed ??(G ') Unit: m / s2 6, the average deceleration fully developed (MFDD) Unit: m / s2