rateControl#

Executive Summary#

This module implements a feedback control law to damp the angular rates of the spacecraft until they are brought to zero.

Message Connection Descriptions#

The following table lists all the module input and output messages. The msg type contains a link to the message structure definition, while the description provides information on what this message is used for.

Module I/O Messages#
Msg Variable Name	Msg Type	Description
vehConfigInMsg	VehicleConfigMsgPayload	Attitude guidance input message
guidInMsg	AttGuidMsgPayload	Vehicle configuration input message
cmdTorqueOutMsg	CmdTorqueBodyMsgPayload	Commanded torque output message

Detailed Module Description#

The control is similar to mrpPD, but does not feed back on the orientation error:

\[{\bf L}_{r} = -K \pmb\sigma - [P] \delta\pmb\omega + [I](\dot{\pmb\omega}_{r} - [\tilde{\pmb\omega}]\pmb\omega_{r}) +[\tilde{\pmb \omega}_{r}] ] [I]\pmb\omega - \bf L\]

where \(P\) is a positive, user-defined scalar quantity.

User Guide#

The required module configuration is:

module = rateDamp.RateDamp()
module.modelTag = "rateDamp"
module.setDerivativeGainP(P)
module.setKnownTorquePntB_B(knownTorquePntB_B)

Class RateControl#

class RateControl : public SysModel#

Public Functions

void reset(uint64_t currentSimNanos) override#

This method performs a complete reset of the module. Local module variables that retain time varying states between function calls are reset to their default values.

Parameters:: callTime – [ns] Time the method is called
Returns:: void

void updateState(uint64_t currentSimNanos) override#

This method takes the attitude and rate errors relative to the reference frame, as well as the reference frame angular rates and acceleration, and computes the required control torque Lr.

Parameters:: callTime – [ns] Time the method is called
Returns:: void

void setDerivativeGainP(double P)#

Setter method for the derivative gain P.

Parameters:: P – [N*m*s] Rate error feedback gain applied
Returns:: void

double getDerivativeGainP() const#

Getter method for the derivative gain P.

Returns:: const double

void setKnownTorquePntB_B(const Eigen::Vector3d &knownTorquePntB_B)#

Setter method for the known external torque about point B.

Parameters:: knownTorquePntB_B – [N*m] Known external torque expressed in body frame components
Returns:: void

const Eigen::Vector3d &getKnownTorquePntB_B() const#

Getter method for the known torque about point B.

Returns:: const Eigen::Vector3d

Public Members

ReadFunctor<AttGuidMsgPayload> guidInMsg#: Attitude guidance input message.

ReadFunctor<VehicleConfigMsgPayload> vehConfigInMsg#: Vehicle configuration input message.

Message<CmdTorqueBodyMsgPayload> cmdTorqueOutMsg#: Commanded torque output message.