This class provides a simple mechanical bladder which is used to control the buoyancy of an underwater glider. It uses Archimedes' principle to apply an upward force based on the volume of the bladder. It listens to the topic buoyancy_engine or /model/{namespace}/buoyancy_engine topic for the volume of the bladder in cubicmeters. More...

#include <BuoyancyEngine.hh>

Public Member Functions
	BuoyancyEnginePlugin ()
	Constructor.

void	Configure (const Entity &_entity, const std::shared_ptr< const sdf::Element > &_sdf, EntityComponentManager &_ecm, EventManager &)
	Configure the system.

void	PreUpdate (const UpdateInfo &_info, EntityComponentManager &_ecm)

Public Member Functions inherited from System
	System ()=default
	Constructor.

virtual	~System ()=default
	Destructor.

Additional Inherited Members
Public Types inherited from System
using	PriorityType = int32_t
	Signed integer type used for specifying priority of the execution order of PreUpdate and Update phases.

Static Public Attributes inherited from System
static constexpr PriorityType	kDefaultPriority = {0}
	Default priority value for execution order of the PreUpdate and Update phases.

static constexpr std::string_view	kPriorityElementName
	Name of the XML element from which the priority value will be parsed.

Detailed Description

This class provides a simple mechanical bladder which is used to control the buoyancy of an underwater glider. It uses Archimedes' principle to apply an upward force based on the volume of the bladder. It listens to the topic buoyancy_engine or /model/{namespace}/buoyancy_engine topic for the volume of the bladder in cubicmeters.

System Parameters

<link_name>: The link which the plugin is attached to [required, string]
<namespace>: The namespace for the topic. If empty the plugin will listen on buoyancy_engine otherwise it listens on /model/{namespace}/buoyancy_engine [optional, string]
<min_volume>: Minimum volume of the engine [optional, float, default=0.00003m^3]
<neutral_volume>: At this volume the engine has neutral buoyancy. Used to estimate the weight of the engine [optional, float, default=0.0003m^3]
<default_volume>: The volume which the engine starts at [optional, float, default=0.0003m^3]
<max_volume>: Maximum volume of the engine [optional, float, default=0.00099m^3]
<max_inflation_rate>: Maximum inflation rate for bladder [optional, float, default=0.000003m^3/s]
<fluid_density>: The fluid density of the liquid its suspended in kgm^-3. [optional, float, default=1000kgm^-3]
<surface>: The Z height in metres at which the surface of the water is. If not defined then there is no surface [optional, float]

Topics

Subscribes to a gz::msgs::Double on buoyancy_engine or /model/{namespace}/buoyancy_engine. This is the set point for the engine.
Publishes a gz::msgs::Double on buoyancy_engine or /model/{namespace}/buoyancy_engine/current_volume on the current volume

Examples

To get started run:

gz sim buoyancy_engine.sdf

Enter the following in a separate terminal:

gz topic -t /model/buoyant_box/buoyancy_engine/ -m gz.msgs.Double \

-p "data: 0.003"

to see the box float up.

gz topic -t /model/buoyant_box/buoyancy_engine/ -m gz.msgs.Double \

-p "data: 0.001"

to see the box go down.

To see the current volume enter:

gz topic -t /model/buoyant_box/buoyancy_engine/current_volume -e

Constructor & Destructor Documentation

◆ BuoyancyEnginePlugin()

BuoyancyEnginePlugin ( )

Constructor.

Member Function Documentation

◆ Configure()

void Configure	(	const Entity &	_entity,
		const std::shared_ptr< const sdf::Element > &	_sdf,
		EntityComponentManager &	_ecm,
		EventManager &	_eventMgr
	)

virtual

Configure the system.

Parameters

[in]	_entity	The entity this plugin is attached to.
[in]	_sdf	The SDF Element associated with this system plugin.
[in]	_ecm	The EntityComponentManager of the given simulation instance.
[in]	_eventMgr	The EventManager of the given simulation instance.