Module: MJActuator

class MJActuatorObject : public MJObject<mjsActuator>
#include <MJActuator.h>

A class representing a MuJoCo actuator object.

MuJoCo actuators, and thus also MJActuatorObject, are single-input single-output. This means that the force/torque produced by the actuator is determined by a single degree of freedom. However, in simulation we usually want to control force and torque along multiple dimensions. Thus, we use MJActuator, which is a collection of MJActuatorObject.

This class wraps a MuJoCo actuator object and provides functionality to update its control value.

Public Functions

void updateCtrl(mjData *data, double value)

Updates the control value of the actuator in the simulation data.

Parameters:

  • data – Pointer to the MuJoCo simulation data.

  • value – The control value to set.

class MJActuator
#include <MJActuator.h>

Base class representing a MuJoCo actuator.

This class represents a general actuator composed of one or more MJActuatorObject instances. It provides methods for configuring the actuator and updating its control values.

MJActuatorObject and MuJoCo actuators are single-input single-output, which means that they can be controlled with only one degree of freedom. For convenience, subclasses of MJActuator represent a useful collection of these 1-dof actuators. See MJSingleActuator, MJForceActuator, MJTorqueActuator, and MJForceTorqueActuator.

Subclassed by MJForceActuator, MJForceTorqueActuator, MJSingleActuator, MJTorqueActuator

Public Functions

inline MJActuator(std::string name, std::vector<MJActuatorObject> &&subActuators)

Constructs an MJActuator with a specified name and actuator objects.

Parameters:

  • name – The name of the actuator.

  • subActuators – A vector of MJActuatorObject representing the individual actuator parts.

MJActuator(const MJActuator&) = delete
MJActuator(MJActuator&&) = delete
MJActuator &operator=(const MJActuator&) = delete
MJActuator &operator=(MJActuator&&) = delete
inline virtual ~MJActuator()

Virtual destructor for MJActuator.

inline const std::string &getName()

Gets the name of the actuator.

Returns:

The name of the actuator.

void configure(const mjModel *model)

Configures the actuator within a given MuJoCo model.

Parameters:

model – Pointer to the MuJoCo model used for configuration.

void updateCtrl(mjData *data)

Updates the control value of the actuator(s) in the MuJoCo data.

Parameters:

data – Pointer to the MuJoCo simulation data.

virtual std::vector<double> readControlMessages() = 0

Reads control messages for the actuator.

This pure virtual function must be implemented by derived classes to read specific control messages.

Returns:

A vector of control values.

Protected Attributes

std::string name

The name of the actuator.

std::vector<MJActuatorObject> subActuators

The individual actuator objects.

class MJSingleActuator : public MJActuator
#include <MJActuator.h>

Class representing a 1-degree-of-freedom actuator.

This actuator type has 1 control degree of freedom. This can be useful to represent forces applied to linear joints, torques applied to revolute joints, or forces/torques applied along a fixed direction.

This class is designed to handle one SingleActuatorMsgPayload message to control the force / torque magnitude applied.

Public Functions

virtual std::vector<double> readControlMessages() override

Reads control messages for a single actuator.

Returns:

A vector containing the control value.

inline MJActuator(std::string name, std::vector<MJActuatorObject> &&subActuators)

Use the same constructor as MJActuator

MJActuator(const MJActuator&) = delete

Use the same constructor as MJActuator

MJActuator(MJActuator&&) = delete

Use the same constructor as MJActuator

Public Members

ReadFunctor<SingleActuatorMsgPayload> actuatorInMsg

Functor to read actuator control messages.

class MJForceActuator : public MJActuator
#include <MJActuator.h>

Class representing an actuator that can exert an arbitrary force vector.

This actuator has 3 degrees of freedom. To achieve this, it’s composed of three 1-degree-of-freedom MJActuatorObject, each applying a force along perpendicular directions.

This class is designed to handle one ForceAtSiteMsgPayload message to control the force vector applied.

Public Functions

virtual std::vector<double> readControlMessages() override

Reads force control messages for the actuator.

Returns:

A vector containing the force control values.

inline MJActuator(std::string name, std::vector<MJActuatorObject> &&subActuators)

Use the same constructor as MJActuator

MJActuator(const MJActuator&) = delete

Use the same constructor as MJActuator

MJActuator(MJActuator&&) = delete

Use the same constructor as MJActuator

Public Members

ReadFunctor<ForceAtSiteMsgPayload> forceInMsg

Functor to read force control messages.

class MJTorqueActuator : public MJActuator
#include <MJActuator.h>

Class representing an actuator that can exert an arbitrary torque vector.

This actuator has 3 degrees of freedom. To achieve this, it’s composed of three 1-degree-of-freedom MJActuatorObject, each applying a torque along perpendicular directions.

This class is designed to handle one TorqueAtSiteMsgPayload message to control the torque vector applied.

Public Functions

virtual std::vector<double> readControlMessages() override

Reads torque control messages for the actuator.

Returns:

A vector containing the torque control values.

inline MJActuator(std::string name, std::vector<MJActuatorObject> &&subActuators)

Use the same constructor as MJActuator

MJActuator(const MJActuator&) = delete

Use the same constructor as MJActuator

MJActuator(MJActuator&&) = delete

Use the same constructor as MJActuator

Public Members

ReadFunctor<TorqueAtSiteMsgPayload> torqueInMsg

Functor to read torque control messages.

class MJForceTorqueActuator : public MJActuator
#include <MJActuator.h>

Class representing an actuator that can exert an arbitrary force and torque vectors.

This actuator has 6 degrees of freedom. To achieve this, it’s composed of size 1-degree-of-freedom MJActuatorObject, each applying a force and torque along perpendicular directions.

This class is designed to handle one ForceAtSiteMsgPayload and one TorqueAtSiteMsgPayload messages to control the force and torque vectors applied.

Public Functions

virtual std::vector<double> readControlMessages() override

Reads force and torque control messages for the actuator.

Returns:

A vector containing the force and torque control values.

inline MJActuator(std::string name, std::vector<MJActuatorObject> &&subActuators)

Use the same constructor as MJActuator

MJActuator(const MJActuator&) = delete

Use the same constructor as MJActuator

MJActuator(MJActuator&&) = delete

Use the same constructor as MJActuator

Public Members

ReadFunctor<ForceAtSiteMsgPayload> forceInMsg

Functor to read force control messages.

ReadFunctor<TorqueAtSiteMsgPayload> torqueInMsg

Functor to read torque control messages.