Propulsion-system reliability

The propulsion model evaluates how the number and placement of operational motors affects vehicle reliability. Motor state is represented by a sequence in which 1 means operational and 0 means failed.

Supported configurations

Configuration	Vehicle	Status-vector length
PNPN	Quadcopter	4
PNPNPN	Hexacopter, alternating rotation	6
PPNNPN	Hexacopter, grouped rotation	6
PPNNPPNN	Octocopter	8

P and N describe the motor rotation direction around the airframe. Because controllability after a motor failure depends on placement, two vehicles with the same number of operational motors can occupy different Markov states.

Example

from SafeDrones.core.SafeDrones import SafeDrones

model = SafeDrones()

p_fail, mttf = model.Motor_Failure_Risk_Calc(
    MotorStatus=[0, 1, 1, 1, 1, 1],
    Motors_Configuration="PNPNPN",
    Motors_Lambda=0.001,
    time=5,
)

Inputs

Parameter	Description
MotorStatus	Ordered operational/failed state for every motor
Motors_Configuration	One of the supported rotation arrangements
Motors_Lambda	Propulsion-unit failure rate, including motor, driver, rotor, and propeller assumptions
time	Mission time at which failure probability is evaluated

Important

Keep MotorStatus in the same physical motor order used by the selected configuration. Reordering the same zeros and ones may change the result.

Decision support

The output can support higher-level logic such as continuing the mission, returning to the station, or initiating a safe landing. The decision thresholds and safety policy remain the responsibility of the integrating system.