Charm hardware properties

Charm is a Scout robot from Nomadic Technologies Inc [14,22].

Figure 3.6: Charm

Charm is not independent. It has to be controlled by a host computer via a serial link. A Motorola MC68332 main processor is responsible for this communication and a DSP processor is responsible for the motor control. Table 3.2 summarizes its physical characteristics.

Table 3.2: Physical characteristics of Charm

diameter	$41 cm$
height	$35 cm$
weight	$23 kg$
payload	$5 kg$
maximum speed	$1.0 m/s$
maximum acceleration	$2 m/s^2$
encoder resolution:
translation	$756 counts/cm$
rotation	$230 counts/degree$

Charm is equipped with 16 sonar sensors and 6 independent bumper switches. It has a two wheel differential drive system. The user can provide the speed of each motor independently.

Charm is controlled by a 486 PC running Linux via its serial port. Therefore, the software of the Scout provided by Nomadic Technologies is mostly compatible with the software of the Nomad 200 [21,22]. This allowed us to change the robot during the project and to run the same code with only a few changes in it. The same graphical user interface as FortyTwo's one can be used with Charm.