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Chapter 5. Evaluation 67

gateway driver

devicemanager

device_changed

visualization &

namespace

simulation

node

protocol_out device_changed_ns

switch_device_nsswitch_deviceprotocol_in

10.4ms 1.8ms

45.8ms 7.8ms

2.2ms

6.9ms

Figure 5.2.: The latency of the complete system. Each time was measured 100 times and has

been averaged.

During normal operation, the maximum number of received protocols during a certain time is

limited to a small number (see ﬁgure 3.6 on page 34). This number can, however, be greatly

increased by using the simulation node, which makes it possible to send messages faster than

they can be processed. As ROS topics are buﬀered internally, the input buﬀers are ﬁlled, and the

node is not jammed. Nevertheless, the message order can be interchanged due to small delays

in communication. As a result, the database entries may be faulty, for example when a device

is turned on and oﬀ and the oﬀ message is received ﬁrst, it will be saved as on. However, this

problem only occurs during simulation and not during real operation. Due to the low message

throughput, the data traﬃc between the nodes can be neglected and was therefore not measured.

5.2. Home and oﬃce scenario

In addition to the previous benchmarks, the system has been tested in two real environments in

order to evaluate its long-term behaviour. The data was recorded with ROS-bag, which enables

them to be analysed for patterns and to be played them back in diﬀerent environments. Figure 5.3

on the following page shows the structure of the oﬃce and home scenario with its devices.

The following device types were used:

• Remote control: A universal IT remote control with four channels (A, B, C and D) for

controlling devices all over the room.

• Contact switches: Simple reed contacts for detecting whether a door or window is open

or closed.

• Passive infrared sensor (PIR): A PIR sensor for presence detection.

• Power plugs: Switchable power plugs for turning electrical appliances on or oﬀ.

• Wall switch: Switches as inputs to turn devices on or oﬀ.

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RFXCOM RFXtrx433 Spezifikationen Seite 74