Table 3.

Safety rules for the smart walker.

Situation	Action	Notes
No legs/only one leg detected, several times sequentially	Increase the counter	There is a counter that increases each time both legs are not detected. If this counter reaches the limit number, the walker stops immediately. The limit number can be defined inside the code. If the leg is detected before the counter reaches the limit, the counter is zeroed.
Counter exceeded limit	Brake the robot	If the counter reaches the maximum limit, it brakes the robot and stops its movement.
High speed	Limit speed	This safety rule is applicable for both linear and angular speeds.
Backwards movement	Brake the robot	Braking the robot in this case means the speed will be set up to zero.
Obstacle (detected by ultrasound sensors)	Brake the robot	The robot is stopped while the obstacle is not removed from the path.