## 11 Hardware and Testbeds
### Hardware Testbeds
The hardware components of the robot consist of mobile platform, 8-bit Rabbit semiconductor R3000 programmable microprocessor with Flash memory, a 320 \(\times\) 240 pixel X10 Cam2 color camera, sensing elements, communication devices, and batteries. Explorebots testbed has been used for target localization experiments by processing the sound and light sensors outputs to guide the robots towards the target source, in addition to validate hybrid routing protocols. **B) Multi-Tier Hardware Testbeds:**  
IrisNet [116], internet- scale resource-intensive sensor network services, is an example of wireless multimedia sensor network Multi-Tier Hardware testbed that provides shared internet-scale long-lived software platform for many sensor applications. IrisNet has been designed to overcome the difficulties of building large-scale distributed networks comprise of many scalar and visual sensors, and the challenges of dealing with large volumes of collected data. Therefore, the proposed platform enables the creation of a planetary infrastructure of multimedia sensors and enables application-specific processing of the collected data by these sensors using their processing capabilities. IrisNet allows user to query the collected information, stored in distributed XML database infrastructure close to its sources, by using internet-like queries. IrisNet also provides a number of multimedia processing primitives that new applications can use as building blocks such as camera calibration, key-points or reference points implementation, and image stitching. The architecture of IrisNet is two-tiered: Sensing Agents tier (SAs) for data collection and filtering, and Organizing Agents tier (OAs) for data storage and querying. There are three steps in order to develop an application using IrisNet. First, the application developer creates the sensor database XML schema that defines the attributes, tags, and hierarchies used to describe and organize distilled sensor data. Second, the application developer writes the software running in the SAs (called senselet) to filter the collected sensory data and update the database defined by the schema. Third, the application developer provides an application-specific front end interface for end users to access the application. In [98], the design and implementation of SenseEye is presented, a multi-tier network of heterogeneous wireless sensor nodes and cameras. SenseEye is designed for surveillance application in WMSN where resource-constrained low-power elements are employed to perform simpler application tasks while more capable high-power elements are used for more complex tasks. The work aims to exploits the advantages of multi-tier sensor network comparing to a single-tier network such as low cost, wide coverage, high functionality, and high reliability by proposing numerous mechanisms and optimizations for object detection, object localization, inter-tier wakeup, object recognition, and tracking. SenseEye is implemented in three-tier network consisting of four types of camera sensors where nodes within each tier are assumed to be homogeneous while different tiers are assumed to be heterogeneous with respect to their capabilities. The processing power, networking capabilities, and imaging resolution improve from the lower tier to the higher tier at the expense of increased power consumption. The lowest tier consists of low-power sensor motes such as MICA2 equipped with low fidelity and resolution camera sensors such as Cyclops or CMUcam3. The second tier consists of Stargate nodes equipped with higher fidelity and medium resolution webcams. The third tier contains a sparse deployment of high resolution pan-tilt-zoom (Sony SNC-RZ30N) cameras connected to embedded PCs. In this system, no base station is assumed and the communication between Tier 1 and Tier 2 is low rate through 900 MHz radio while the communication between Tier 2 and Tier 3 is done through 802.11 radio.