Sensor Power Model

Description

The Sensor Power Model is a Power Node Model that simulates power consumption for Sensor components. It models the sensor as a Constant Power Load (CPL), dynamically adjusting resistance so the sensor draws approximately the same power regardless of input voltage variations. The model supports automatic shutdown on power loss and restart when power is restored.

Example Use Cases

Sensor Power Simulation: Model realistic power draw across operational, standby, and shutdown states.
Power Budget Analysis: Evaluate sensor power consumption during different mission phases.
Brownout Protection: Simulate automatic sensor shutdown when voltage or power falls below operational thresholds.

Module Implementation

Power Consumption by State

The model defines configurable power consumption values for each sensor state:

State	Default Power (W)	Description
Operational	3.0	Sensor is actively measuring
Standby	0.65	Sensor is idle but ready
Shutdown	0.0	Sensor is disabled

Constant Power Load Model

The sensor is modeled as a CPL using quasi-static iteration. Each tick, the resistance is recomputed from the previous tick’s solved voltage:

R = \frac{V ^{2}}{P}

where $V$ is the voltage from the previous solve (or nominal voltage $V_{n}$ on the first tick) and $P$ is the target power for the current state. The voltage is floored at the minimum operational threshold to prevent resistance collapse during transient brownouts.

Brownout Detection

The model monitors two thresholds to detect insufficient power:

Voltage Threshold: The solved voltage must remain above a minimum fraction of the nominal operational voltage (default $V_{n} = 12$ V):

V_{node} \geq V_{n} \times r_{V}

where $r_{V}$ is the minimum voltage ratio (default 0.8).

Power Threshold: The absorbed electrical power must remain above a minimum fraction of the expected state power:

P_{absorbed} \geq P_{state} \times r_{P}

where $r_{P}$ is the minimum power ratio (default 0.13). Setting $r_{P} = 0$ disables this check.

State Management

The power model automatically manages the sensor’s operational state:

Power Loss: When voltage or power falls below thresholds, or the circuit becomes open, the model shuts down the sensor and sets the ModelShutdown flag.
Power Restored: When power is restored and the sensor is shut down with ModelShutdown set, the model automatically returns the sensor to Operational state.

Assumptions/Limitations

The power model must be attached to a Sensor component.
Power consumption values are constant for each state; dynamic power scaling is not modeled.
The quasi-static CPL iteration converges over multiple simulation ticks.
When manually changed to a state other than Shutdown while ModelShutdown is set, the flag is cleared.

Zendir