Low Cost Indoor Positioning System

Autonomous indoor ultrasonic positioning system based on a low-cost conditioning circuit

“…The system is based on a low-cost FPGA [16,17] and also inexpensive electronics. Nonetheless, the proposed system achieves a similar or better accuracy (few centimeters) than previous systems using a PC [7,8,9,10,11,12,13] with the exception of [14] which obtains an accuracy of millimeters but using also inertial sensors. The key component of the system, which is also a novelty, is the ad-hoc conditioning circuit for the amplification of the received ultrasonic signal.…”

“…This differs from the traditional approach which uses envelope or tone detectors for the 40 kHz component. In our case, the 40 kHz detection is accomplished inside the FPGA with a state machine and timers, reducing the cost of the system and avoiding the delay and uncertainty introduced by envelope detection, as shown in [10]. Furthermore, circuit.…”

“…Both systems use RF transmissions in order to synchronize transmitters with receivers. The location system of Randell and Muller [10] also has a passive ultrasonic-based system using radiofrequency. Later, these authors improved the system [11,12] eliminating the radiofrequency, but requiring harder processing, such as the use of the Kalman filter.…”

A framework for designing sensor-based interactions to promote exploration and reflection in play

“…This mode of operating ignores the continuous part of the activity altogether. In order to take the continuous part of the searching activity into account, we employed an enhanced ultrasound position sensing device (Randell and Muller, 2001) which tells the PDA where it is at any one time, and a compass that measures the orientation of the device. Having the additional information of location and orientation, enables various display formats to be designed to show where the person holding it is and where the hidden objects are.…”

Designing Engaging Experiences with Children and Artists

“…Equipped with headphones connected to a small shoulder bag, visitors typically spend around twenty minutes wandering around the exhibition, viewing the photographs and listening to audio pieces chosen to enhance the images (see figure 3). The particular sounds heard by a visitor at any point are determined automatically by a small computer system in the bag that monitors the visitor's location within the exhibition space [4,5]. For example, when standing close to certain photographs, a visitor might hear atmospheric music fitting the scenes depicted.…”