and link i. θi is the angle between link i-1 and link i. θi is the
joint variable. i is from 1 to 6. The default values of θi are -90°,
-120°, -90°, 210°, 90°, and 90° respectively. The ranges of the
joint variables and the parameters of the links are shown in
Table I. The six rotation joints are driven by six servo motors.
The hardware components of the robot are shown in Fig. 5.
The power supply module can convert the 7.4 V voltage of the
primary battery or the battery backup to 5V for the motors and
3.3V for the control module and the sensors. If the primary a
battery is exhausted, the battery backup will provide power for
the robot during the battery swapping process. The control
module controls other modules and sensors. The Wi-Fi
module transmits data between the robot and the home server.
The DC motor driving module drives the four DC motors of
the wheels. The servo motor driving module drives the six
servo motors of the manipulator and two servo motors of the
camera. The battery voltage sensor detects the voltages of the
primary battery and the battery backup. The camera provides
video information for the user to control the robot remotely.