The data acquired by the various sensors is stored in the onboard computer. At the end of the test, the onboard computer can be connected to an Ethernet network and the data can be downloaded on to another PC for offline analysis. A software application was developed for the offline data review and analysis, shown below. This application includes a review module that can be used to review the test data and view graphs that plot various parameters against time, such as pressure, acceleration, speed, and brake-pad temperature.OperationThe encoder used in this system gives an output of 1,000 ppr. The encoder shaft connects to the front wheel of the motorbike. The encoder output connects to the two counters of the DAQ card. We measure the duration between the encoder pulses to obtain the instantaneous speed of the vehicle and another counts the number of pulses, which is translated into displacement.
We need reference signals to start and stop the counters during braking. The start signal is obtained from the pressure sensor, which is mounted on the disk brake hydraulic cylinder. The pressure signal is a trigger to start counting the pulses. Zero speed is the stop signal to stop counting the pulses. A low cut-off speed is used to detect the zero speed condition. The figure below shows a schematic that depicts this basic scheme used for measuring braking distance.
With the user interface kit and integrated LCD display and keyboard, the user can enter various speeds at which to start braking, and the LabVIEW application monitors the motorbike speed and gives a signal to start braking at the desired speed range. When the bike comes to a stop, the display immediately shows the braking distance. During the braking, the brake -pad temperature and acceleration are also acquired using the high-speed data acquisition card.ConclusionThe on-road brake test system we developed can measure braking distance to an accuracy of 1% over a distance of 30 m. The system also handled wheel-lock conditions by using the accelerometer data during these periods. The small form factor of the NI PCMCIA data acquisition cards and the FieldWorks 2000 embedded computer made it easy to mount it on the motorbike. The whole system was rugged enough to handle accidental falls during testing. With user interface, the user can set up different tests during the road trials and also see the results without having to connect a laptop to the embedded computer. We plan to make the system more user friendly by interfacing a microphone to one of the DAQ channels, so the rider can record comments during the tests.
We need reference signals to start and stop the counters during braking. The start signal is obtained from the pressure sensor, which is mounted on the disk brake hydraulic cylinder. The pressure signal is a trigger to start counting the pulses. Zero speed is the stop signal to stop counting the pulses. A low cut-off speed is used to detect the zero speed condition. The figure below shows a schematic that depicts this basic scheme used for measuring braking distance.
With the user interface kit and integrated LCD display and keyboard, the user can enter various speeds at which to start braking, and the LabVIEW application monitors the motorbike speed and gives a signal to start braking at the desired speed range. When the bike comes to a stop, the display immediately shows the braking distance. During the braking, the brake -pad temperature and acceleration are also acquired using the high-speed data acquisition card.ConclusionThe on-road brake test system we developed can measure braking distance to an accuracy of 1% over a distance of 30 m. The system also handled wheel-lock conditions by using the accelerometer data during these periods. The small form factor of the NI PCMCIA data acquisition cards and the FieldWorks 2000 embedded computer made it easy to mount it on the motorbike. The whole system was rugged enough to handle accidental falls during testing. With user interface, the user can set up different tests during the road trials and also see the results without having to connect a laptop to the embedded computer. We plan to make the system more user friendly by interfacing a microphone to one of the DAQ channels, so the rider can record comments during the tests.
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