CITRIC: A low-bandwidth wireless camera network platform

In this paper, we propose and demonstrate a novel wireless camera network system, called CITRIC. The core component of this system is a new hardware platform that integrates a camera, a frequency-scalable (up to 624 MHz) CPU, 16 MB FLASH, and 64 MB RAM onto a single device. The device then connects with a standard sensor network mote to form a camera mote. The design enables in-network processing of images to reduce communication requirements, which has traditionally been high in existing camera networks with centralized processing. We also propose a back-end client/server architecture to provide a user interface to the system and support further centralized processing for higher-level applications. Our camera mote enables a wider variety of distributed pattern recognition applications than traditional platforms because it provides more computing power and tighter integration of physical components while still consuming relatively little power. Furthermore, the mote easily integrates with existing low-bandwidth sensor networks because it can communicate over the IEEE 802.15.4 protocol with other sensor network platforms. We demonstrate our system on three applications: image compression, target tracking, and camera localization

Development and application of stereo camera-based upper extremity workspace evaluation in patients with neuromuscular diseases.

BackgroundThe concept of reachable workspace is closely tied to upper limb joint range of motion and functional capability. Currently, no practical and cost-effective methods are available in clinical and research settings to provide arm-function evaluation using an individual's three-dimensional (3D) reachable workspace. A method to intuitively display and effectively analyze reachable workspace would not only complement traditional upper limb functional assessments, but also provide an innovative approach to quantify and monitor upper limb function.Methodology/principal findingsA simple stereo camera-based reachable workspace acquisition system combined with customized 3D workspace analysis algorithm was developed and compared against a sub-millimeter motion capture system. The stereo camera-based system was robust, with minimal loss of data points, and with the average hand trajectory error of about 40 mm, which resulted to ~5% error of the total arm distance. As a proof-of-concept, a pilot study was undertaken with healthy individuals (n = 20) and a select group of patients with various neuromuscular diseases and varying degrees of shoulder girdle weakness (n = 9). The workspace envelope surface areas generated from the 3D hand trajectory captured by the stereo camera were compared. Normalization of acquired reachable workspace surface areas to the surface area of the unit hemi-sphere allowed comparison between subjects. The healthy group's relative surface areas were 0.618±0.09 and 0.552±0.092 (right and left), while the surface areas for the individuals with neuromuscular diseases ranged from 0.03 and 0.09 (the most severely affected individual) to 0.62 and 0.50 (very mildly affected individual). Neuromuscular patients with severe arm weakness demonstrated movement largely limited to the ipsilateral lower quadrant of their reachable workspace.Conclusions/significanceThe findings indicate that the proposed stereo camera-based reachable workspace analysis system is capable of distinguishing individuals with varying degrees of proximal upper limb functional impairments

Relative contribution of each quadrant surface to the overall surface area of the reachable workspace envelope as assessed in the group of healthy controls.

<p>Relative contribution of each quadrant surface to the overall surface area of the reachable workspace envelope as assessed in the group of healthy controls.</p

Patient data and corresponding results of the surface envelope assessment are presented as the average value over three trials.

*<p>BMD: Becker muscular dystrophy; DMD: Duchenne muscular dystrophy; FSHD: Facioscapulohumeral dystrophy; Pompe: Pompe disease (glycogen storage disease type II).</p

Relative surface area of the reachable workspace envelope as measured in the healthy controls and patients with different neuromuscular diseases (See <b>Tables 1</b> and <b>2</b> for details and corresponding absolute values).

<p>Relative surface area of the reachable workspace envelope as measured in the healthy controls and patients with different neuromuscular diseases (See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0045341#pone-0045341-t001" target="_blank"><b>Tables 1</b></a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0045341#pone-0045341-t002" target="_blank"><b>2</b></a> for details and corresponding absolute values).</p