The Notices and Disclaimers for Ocean Worlds Autonomy Testbed for Exploration Research and Simulation can be found in README.md in the root directory of this repository.

ow_power_system

It creates a node called power_system_node, which monitors power consumption (mainly based off mechanical power at the current time), publishes the messages from the owl_msgs package that individually describe the estimated state of charge (SOC), estimated remaining useful life (RUL) in seconds and also publishes the estimated battery temperature in degrees Celsius. To monitor any of these values simply subscribe to their respective topics:

rostopic echo /battery_state_of_charge
rostopic echo /battery_remaining_useful_life
rostopic echo /battery_temperature

state_of_charge (SOC): The SOC estimate provides the amount of energy present in the battery. It varies from 0 - 100%. When the SOC level goes below a certain set threshold a fault is detected.

remaining_useful_life (RUL): The RUL estimate is that of the time remaining before the battery reaches the set SOC threshold.

battery_temperature: The internal battery temperature changes based on the operating conditions. The battery temperature should not rise above a certain threshold to prevent the battery from going into thermal runaway.

The RUL, SOC, and battery temperature values are computed via the GSAP prognostics library based on power input values from a precomputed constant or variable load csv. The values are published every second.

The predicted RUL and SOC values are expected to fluctuate slightly (rather than decrease monotonically) due to uncertainties in the Monte Carlo predictor method, with the predicted value becoming more accurate closer to EOD (end of discharge). The battery temperature is expected to hover around a constant value of approximately 20 degrees C.

You may initialize the power_system_node in ros launch file as follows:

<node name="power_system_node" pkg="ow_power_system" type="power_system_node" />

NOTE: Currently the frequency of the three topics is dependent on the update rate of the mechanical power topic which itself is dependent on the frequency of joint_states topics. This likely to change.