Wireless Control via Bluetooth

University essay from Lunds universitet/Industriell elektroteknik och automation

Author: Asta Andresdottir; [2009]

Keywords: Technology and Engineering;

Abstract: A personal transporter is under development at LTH, Industrial Electrical Engineering and Automation, IEA. A wireless link is desired to develop control remotely for the transporter. The development of the control becomes easier without wires and if the transporter can move freely within the range of the link. A link is built, using Bluetooth devices and a microprocessor from Microchip. This link is able to carry an eight bit signal back and forth. The development of the transporter has not reached a state in which it can receive or transmit signals. Instead the link is tested with a signal generator and an oscilloscope at first and then for DC-motor control. A test run is carried out with a signal generator and an oscilloscope. A signal is created with the signal generator, which is fed to the microcontroller that forwards the signal by a Bluetooth transceiver. Another Bluetooth transceiver receives the signal at the remote site. The signal is forwarded to a computer hosted control system, dSPACE, and a control signal is produced. The control signal is sent back to the microprocessor by the Bluetooth transceivers and forwarded to an oscilloscope via a D/A converter. The link is furthermore used to control a DC motor. A PWM signal is created using the microcontroller and forwarded to the motor via an H-bridge, an electronic circuit that controls the direction and velocity of the DC motor. A potentiometer is used to sense the location of the motor. The voltage from the potentiometer is forwarded to the microcontroller that converts it to a digital signal. The digital signal for the measurement is sent through the Bluetooth transceivers to dSPACE where the desired control signal is calculated. The control signal is sent to the microcontroller that generates the corresponding PWM signal. An 8 bit signal can be sent and received with the wireless Bluetooth link. Some problems occurred with buffer overflows, which were eliminated by tuning the sampling of signals. The range of the wireless link is close to 40 m and should be enough to develop control for the transporter. Depending on the amount of signals, that affect the control of the transporter, a multichannel link might be desirable.

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