Human body tracking with electric field ranging

Abstract

This paper presents a passive, simple, and affordable electric field based ranging method for capturing human position, leaning, and hand or leg movements. A test system transforms the physical input into a two-dimensional position in an indoor environment. The method and the designed test system can be used, for example, in gaming, virtual exhibition, and virtual reality applications. The proposed system measures the capacitances between a user, standing on a transmitting floor electrode, and four vertically aligned receiver wires placed at the corners of the tracking area. The system converts the measured capacitances to absolute distances, which in turn can be used to resolve the unambiguous position of the user. The design was verified in a 1.8 x 1.8 m-sized test space by using the structures of a virtual reality cave. The test system can track a human body with relative accuracy of less than 10.4 cm at an update rate of 19.5 Hz.

Capacitive User Tracking Methods for Smart Environments

“…The test system which was constructed and described in publication [49] demonstrates that a person's body position and movements can be tracked passively with a simple electrode configuration and affordable electronics by converting the measured capacitances to absolute distances. The system works with different size people and in some applications the correction factor k could be used to adequately identify different-sized people or to identify the insulation properties of an individual's footwear.…”

“…Moreover, this method allows even slight movements, such as leaning or moving an arm or a leg, to be discerned, assuming that an adequate signal can be received by the receivers. As was demonstrated in publication [49], this method allows the test system developed in publication [49] to be used not only for human position tracking, but also in gaming, virtual exhibitions, and virtual reality applications.…”

“…By measuring the user distance from the vertical wires placed in each corner of the tracking space, the user position can be calculated and used in addition to indoor positioning, for example, to control a flight simulator game. [49] into a two-dimensional position in an indoor environment. The method and a demonstration platform has been built and presented in detail in [49] and will be presented in this section with sufficient details about the system structure, capacitance model and results for the reader to understand the operation and possibilities of the measurement setup.…”

“…[49] into a two-dimensional position in an indoor environment. The method and a demonstration platform has been built and presented in detail in [49] and will be presented in this section with sufficient details about the system structure, capacitance model and results for the reader to understand the operation and possibilities of the measurement setup. Although this test system at the current state of development can only be used in small scale setups, it provides interesting possibilities to application developers, for example, in gaming, virtual exhibition, and virtual reality industries.…”

“…The test system described in publication [49] consists of a single large transmitter, 180×180 cm in size with four vertical wire receivers placed at the corners of the transmitter. The transmitter consist of nine commercial raised floor tiles that have been electrically connected, and the receivers are made of standard power-line cables.…”