6DOF Acceleration

Compute acceleration of body in six-degrees-of-freedom motion

Since R2025a

• 

Libraries:
Aerospace Blockset / Equations of Motion / Acceleration

Description

The 6DOF Acceleration block computes the acceleration of a body in six-degrees-of-freedom motion with respect to body-fixed coordinate frame and inertial (flat Earth) coordinate frame. Use this block for only these 6DOF equations of motion blocks:

• 6DOF (Euler Angles)

• 6DOF (Quaternion)

• Custom Variable Mass 6DOF (Euler Angles)

• Custom Variable Mass 6DOF (Quaternion)

• Simple Variable Mass 6DOF (Euler Angles)

• Simple Variable Mass 6DOF (Quaternion)

To compute the acceleration for these blocks:

• Select Output mass properties for acceleration computation.

• Feed signals from the matching output ports of the associated 6DOF equation of motion block into the associated input ports of 6DOF Acceleration.

Tip

Match all the parameter values for 6DOF Acceleration and the 6DOF equations of motion blocks.

Ports

Input

V_b — Velocity in body-fixed frame

three-element vector

Velocity in body-fixed frame, specified as a three-element vector, in the units selected in Units.

Data Types: double

ω_b (rad/s) — Angular rates in body-fixed axes

three-element vector

Angular rates in body-fixed axes, specified as a three-element vector, in radians per second.

Data Types: double

Fuel — Fuel tank status

scalar

Fuel tank status, specified as:

• 1 — Tank is full.

• 0 — Tank is neither full nor empty.

• -1 — Tank is empty.

Dependencies

To enable this port, set Mass type to Simple Variable.

Data Types: double

m — Mass

scalar

Mass, specified as a scalar, in the units selected in Units.

Data Types: double

F_xyz — Applied forces

three-element vector

Applied forces, specified as a three-element vector, in the units selected in Units.

Data Types: double

dm/dt — Rates of change of mass

scalar

One or more rates of change of mass (positive if accreted, negative if ablated), specified as a scalar, in the units selected in Units.

Dependencies

To enable this port, set Mass type to Simple Variable or Custom Variable.

Data Types: double

V_re — Relative velocities

three-element vector

One or more relative velocities at which the mass is accreted to or ablated from the body in body-fixed axes, specified as a three-element vector, in the units selected in Units.

Dependencies

To enable this port:

• Set Mass type to Simple Variable or Custom Variable.

• Select Include mass flow relative velocity.

Data Types: double

Output

A_bb — Accelerations in body-fixed axes

three-element vector

Accelerations of the body with respect to the body-fixed axes with the body-fixed coordinate frame, returned as a three-element vector, in the units selected in Units.

Data Types: double

A_be — Accelerations with respect to inertial frame

three-element vector

Accelerations in body-fixed axes with respect to inertial frame (flat Earth), returned as a three-element vector. You typically connect this signal to the accelerometer, in the units selected in Units.

Data Types: double

Parameters

To edit block parameters interactively, use the Property Inspector. From the Simulink^® Toolstrip, on the Simulation tab, in the Prepare gallery, select Property Inspector.

Units — Input and output units

Metric (MKS) (default) | English (Velocity in ft/s) | English (Velocity in kts)

Input and output units, specified as Metric (MKS), English (Velocity in ft/s), or English (Velocity in kts).

Units	Forces	Moment	Acceleration	Velocity	Position	Mass	Inertia
Metric (MKS)	Newton	Newton-meter	Meters per second squared	Meters per second	Meters	Kilogram	Kilogram meter squared
English (Velocity in ft/s)	Pound	Foot-pound	Feet per second squared	Feet per second	Feet	Slug	Slug foot squared
English (Velocity in kts)	Pound	Foot-pound	Feet per second squared	Knots	Feet	Slug	Slug foot squared

Programmatic Use

Block Parameter: units

Type: character vector

Values: Metric (MKS) | English (Velocity in ft/s) | English (Velocity in kts)

Default: Metric (MKS)

Mass type — Mass type

Fixed (default) | Simple Variable | Custom Variable

Mass type, specified according to the following table.

Mass Type	Description	Default for
Fixed	Mass is constant throughout the simulation.	6DOF (Euler Angles) 6DOF (Quaternion)
Simple Variable	Mass and inertia vary linearly as a function of mass rate.	Simple Variable Mass 6DOF (Euler Angles) Simple Variable Mass 6DOF (Quaternion)
Custom Variable	Mass and inertia variations are customizable.	Custom Variable Mass 6DOF (Euler Angles) Custom Variable Mass 6DOF (Quaternion)

The Simple Variable selection conforms to the previously described equations of motion.

Programmatic Use

Block Parameter: mtype

Type: character vector

Values: Fixed | Simple Variable | Custom Variable

Default: 'Fixed'

Include mass flow relative velocity — Mass flow relative velocity port

off (default) | on

Select this check box to add a mass flow relative velocity port. This is the relative velocity at which the mass is accreted or ablated.

Dependencies

To enable this parameter, set Mass type to Simple Variable or Custom Variable.

Programmatic Use

Block Parameter: vre_flag

Type: character vector

Values: off | on

Default: off

Version History

Introduced in R2025a