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UMjMuscleActuator

Specific Muscle Actuator component.

Attribute Value
Kind Class
UE Macro UCLASS
Inherits UMjActuator
Blueprint Spawnable ✅ Yes

Properties

Public Properties

Property Type Description
TimeConst float Time constant for activation dynamics.
TimeConst2 float Second time constant (e.g. deactivation time).
TauSmooth float Smoothing time constant.
Force float Peak active force.
Scale float Force scaling factor.
LMin float Minimum fiber length.
LMax float Maximum fiber length.
VMax float Maximum shortening velocity.
FPMax float Peak passive force.
FVMax float Peak viscous force.
Type EMjActuatorType The type of actuator dynamics (e.g. Motor, Position).
TransmissionType EMjActuatorTrnType The transmission type connecting the actuator to the system.
MjClassName FString Optional MuJoCo class name to inherit defaults from.
TargetName FString Name of the target element (Joint, Tendon, Site, etc.) this actuator acts upon.
Gear TArray<float> Gear ratio scaling for the transmission.
GainPrm TArray<float> Custom gain parameters (gainprm).
BiasPrm TArray<float> Custom bias parameters (biasprm).
bCtrlLimited bool Whether control limiting is enabled.
bForceLimited bool Whether force limiting is enabled.
bActLimited bool Whether internal activation state is limited.
CrankLength float Length range for muscle/tendon actuators.
SliderSite FString Name of the slider site for slider-crank transmission.
RefSite FString Reference site name.
Group int Actuator group ID.
bActEarly bool Whether to apply actuation early (before other forces).
DynPrm TArray<float> Custom dynamic parameters (dynprm).

TimeConst

Time constant for activation dynamics.

  • Type: float
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator|Parameters
  • Notes: Override-enabled (bOverride_TimeConst)

TimeConst2

Second time constant (e.g. deactivation time).

  • Type: float
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator|Parameters
  • Notes: Override-enabled (bOverride_TimeConst2)

TauSmooth

Smoothing time constant.

  • Type: float
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator|Parameters
  • Notes: Override-enabled (bOverride_TauSmooth)

Force

Peak active force.

  • Type: float
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator|Parameters
  • Notes: Override-enabled (bOverride_Force)

Scale

Force scaling factor.

  • Type: float
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator|Parameters
  • Notes: Override-enabled (bOverride_Scale)

LMin

Minimum fiber length.

  • Type: float
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator|Parameters
  • Notes: Override-enabled (bOverride_LMin)

LMax

Maximum fiber length.

  • Type: float
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator|Parameters
  • Notes: Override-enabled (bOverride_LMax)

VMax

Maximum shortening velocity.

  • Type: float
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator|Parameters
  • Notes: Override-enabled (bOverride_VMax)

FPMax

Peak passive force.

  • Type: float
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator|Parameters
  • Notes: Override-enabled (bOverride_FPMax)

FVMax

Peak viscous force.

  • Type: float
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator|Parameters
  • Notes: Override-enabled (bOverride_FVMax)

Type

The type of actuator dynamics (e.g. Motor, Position).

  • Type: EMjActuatorType
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator

TransmissionType

The transmission type connecting the actuator to the system.

  • Type: EMjActuatorTrnType
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator

MjClassName

Optional MuJoCo class name to inherit defaults from.

  • Type: FString
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator

TargetName

Name of the target element (Joint, Tendon, Site, etc.) this actuator acts upon.

  • Type: FString
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator

Gear

Gear ratio scaling for the transmission.

  • Type: TArray
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator
  • Notes: Override-enabled (bOverride_Gear)

GainPrm

Custom gain parameters (gainprm).

  • Type: TArray
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator
  • Notes: Override-enabled (bOverride_GainPrm)

BiasPrm

Custom bias parameters (biasprm).

  • Type: TArray
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator
  • Notes: Override-enabled (bOverride_BiasPrm)

bCtrlLimited

Whether control limiting is enabled.

  • Type: bool
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator
  • Notes: Override-enabled (bOverride_CtrlLimited)

bForceLimited

Whether force limiting is enabled.

  • Type: bool
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator
  • Notes: Override-enabled (bOverride_ForceLimited)

bActLimited

Whether internal activation state is limited.

  • Type: bool
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator
  • Notes: Override-enabled (bOverride_ActLimited)

CrankLength

Length range for muscle/tendon actuators.

  • Type: float
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator
  • Notes: Override-enabled (bOverride_LengthRange)

SliderSite

Name of the slider site for slider-crank transmission.

  • Type: FString
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator

RefSite

Reference site name.

  • Type: FString
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator

Group

Actuator group ID.

  • Type: int
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator
  • Notes: Override-enabled (bOverride_Group)

bActEarly

Whether to apply actuation early (before other forces).

  • Type: bool
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator
  • Notes: Override-enabled (bOverride_ActEarly)

DynPrm

Custom dynamic parameters (dynprm).

  • Type: TArray
  • Editor: ✏️ EditAnywhere
  • Blueprint: 🔵 ReadWrite
  • Category: Mj Actuator
  • Notes: Override-enabled (bOverride_DynPrm)

Functions

Public Functions

General

Function Returns Description
ImportFromXml() void Imports properties and override flags directly from the raw XML node.
ParseSpecifics() void Parses subclass-specific properties from the XML node.
ExtractSpecifics() void Extracts subclass-specific properties from the MuJoCo spec mechanism.
RegisterToSpec() void Registers this actuator to the MuJoCo spec.
Bind() void Binds this component to the live MuJoCo simulation.
GetMjName() FString Gets the full prefixed name of this actuator as it appears in the compiled MuJoCo model.
ResolveDesiredControl() float Resolves the final control value to apply based on the specified source.
SetNetworkControl() void Sets the control value from the ZMQ networked stream.
ImportFromXml

Imports properties and override flags directly from the raw XML node.

  • Signature: ImportFromXml(const class FXmlNode* Node)
ParseSpecifics

Parses subclass-specific properties from the XML node.

  • Signature: ParseSpecifics(const class FXmlNode* Node)
ExtractSpecifics

Extracts subclass-specific properties from the MuJoCo spec mechanism.

  • Signature: ExtractSpecifics(const mjsActuator* Actuator)
RegisterToSpec

Registers this actuator to the MuJoCo spec.

Bind

Binds this component to the live MuJoCo simulation.

  • Signature: Bind(mjModel* Model, mjData* Data, const FString& Prefix)
GetMjName

Gets the full prefixed name of this actuator as it appears in the compiled MuJoCo model.

  • Signature: GetMjName()
  • Returns: FString
ResolveDesiredControl

Resolves the final control value to apply based on the specified source.

  • Signature: ResolveDesiredControl(uint8 Source)
  • Returns: float
SetNetworkControl

Sets the control value from the ZMQ networked stream.

  • Signature: SetNetworkControl(float Value)

MuJoCo|Runtime

Function Returns Description
SetControl() void Sets the internal control input (ctrl) for this actuator.
ResetControl() void Resets the control input (ctrl) for this actuator to zero.
GetControl() float Gets the current resolved control value being applied.
GetForce() float Gets the current force generated by this actuator.
GetLength() float Gets the current length of the actuator.
GetVelocity() float Gets the current velocity of the actuator.
GetControlRange() FVector2D Gets the control range [min, max] from the compiled model. Returns ZeroVector if ctrl is not limited.
GetActivation() float Gets the current activation state (for stateful actuators like muscle/intvelocity). Returns 0 if stateless.
SetGear() void Sets the gear ratio (expert use).
GetGear() TArray<float> Gets the gear ratio.
SetControl

Sets the internal control input (ctrl) for this actuator.

  • Signature: SetControl(float Value)
  • Blueprint: 🔵 Callable
ResetControl

Resets the control input (ctrl) for this actuator to zero.

  • Signature: ResetControl()
  • Blueprint: 🔵 Callable
GetControl

Gets the current resolved control value being applied.

  • Signature: GetControl()
  • Blueprint: 🔵 Callable
  • Returns: float
GetForce

Gets the current force generated by this actuator.

  • Signature: GetForce()
  • Blueprint: 🔵 Callable
  • Returns: float
GetLength

Gets the current length of the actuator.

  • Signature: GetLength()
  • Blueprint: 🔵 Callable
  • Returns: float
GetVelocity

Gets the current velocity of the actuator.

  • Signature: GetVelocity()
  • Blueprint: 🔵 Callable
  • Returns: float
GetControlRange

Gets the control range [min, max] from the compiled model. Returns ZeroVector if ctrl is not limited.

  • Signature: GetControlRange()
  • Blueprint: 🔵 Callable
  • Returns: FVector2D
GetActivation

Gets the current activation state (for stateful actuators like muscle/intvelocity). Returns 0 if stateless.

  • Signature: GetActivation()
  • Blueprint: 🔵 Callable
  • Returns: float
SetGear

Sets the gear ratio (expert use).

  • Signature: SetGear(const TArray<float>& NewGear)
  • Blueprint: 🔵 Callable
GetGear

Gets the gear ratio.

  • Signature: GetGear()
  • Blueprint: 🔵 Callable
  • Returns: TArray