Submitted version of the thesis - Airlab, the Artificial Intelligence ...

3.6. Batteries 31
itself also works fine for user buttons and switches as well. There are many
designs possible for bump switches, often depending on the design goals of
the robot itself. But the circuit remains the same. They usually implement
a mechanical button to short the circuit, pulling the signal line high or low.
An example is the micro switch with a lever attached to increase its range,
as shown in Figure 3.11. The cost is nothing if compared to the other solutions
such as photo-resistors and sonars, and the usage is pretty simple since
the values can be read directly from the microcontroller pins without having
any control circuits. Major drawback is its limited range, but we tried to
improve the range using the foam and the external springs attached to the
foam. Since the robot is light in the weight and collision can be useful in
development of games, we decided to use tactile bumpers.
Figure 3.11: Bumpers are mechanical buttons to short the circuit, pulling the signal
line high or low.
The collision detection for robot is made with bumpers, which are placed
ontheplexiglas every 60 ◦ (Figure3.12). Thecoverage was not enough, sothe
bumpers are covered with foams which are connected to the springs. The
springs are enabling the push back of the switches, the foams are increasing
the coverage of the collision detection and also enhance the safety both for
the damage that could be caused by the robot and to the robot from environment
(Figure 3.13). After some tests we realized there are still dead
points which the collision are not detected. We decided to cut the foam into
three, placing the around the robot leaving the parts with the wheel open.
The best results are obtained using this configuration so we decided to keep
it.
3.6 Batteries
The robot’s battery life without the need of recharging is crucial for the
game. The game play must continue for about 2 hours without any interruption.
This brings the question of how to choose the correct battery.
LiPo batteries are suitable battery choice for our application over conven-