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MotionSolve Reference Guide
This manual provides a detailed list and usage information regarding command statements, model statements, functions and the Subroutine Interface available in MotionSolve.
Model Statements
Force: Gravity
Model ElementForce_Gravity defines the acceleration due to gravity along the global X, Y, and Z directions.

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Overview
MotionSolve^® is an integrated solution to analyze, evaluate, and optimize the performance of multibody systems.
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MotionSolve User Guide
MotionSolve is a system level, multibody solver that is based on the principles of mechanics.
MotionSolve Reference Guide
This manual provides a detailed list and usage information regarding command statements, model statements, functions and the Subroutine Interface available in MotionSolve.
- Notation and Syntax
- Creating MotionSolve XML Files
- Writing Custom Elements for MotionSolve
- Writing Custom Functions for MotionSolve
- Supported Versions - Third Party Software
- Command Statements
- Model Statements
  - Body: Flexible
    Model ElementBody_Flexible defines a flexible body object in MotionSolve.
  - Body: Rigid
    Model ElementBody_Rigid defines a rigid body object in MotionSolve. This entity has mass and inertia properties.
  - Constraint: Coupler
    Model ElementCOUPLER defines an algebraic relationship between the degrees of freedom of two or three joints.
  - Constraint: CVCV
    Model ElementConstraint_CVCV defines higher pair constraint. The constraint consists of a 3D curve fixed on one body rolling and sliding on a 3D curve fixed on a second body. The curves are required to have a unique point of contact and a common tangent at that point of contact.
  - Constraint: CVSF
    Model ElementConstraint_CVSF defines a higher pair constraint. A curve on one body slides on a surface that is fixed to a second body. The curve is not allowed to lift off the surface.
  - Constraint: Gear
    Model ElementConstraint_Gear defines a gear constraint between two bodies.
  - Constraint: General
    Model ElementThe Constraint_General element is used to specify a user defined general constraint.
  - Constraint: Joint
    Model ElementConstraint_Joint is used to specify an idealized connector between two bodies.
  - Constraint: Mate
    Model ElementConstraint_MATE is used to specify general mating constraints between geometric primitives.
  - Constraint: Primitive
    Model ElementConstraint_Jprim is used to remove degrees of freedom between two bodies by specifying conditions in which the relative translational or rotational motion can occur.
  - Constraint: PTCV
    Model ElementConstraint_PTCV defines a higher pair constraint. A fixed point on one body slides on a curve that is fixed on a second body. The point is not allowed to lift off the curve.
  - Constraint: PTdCV
    Model ElementThe Constraint_PTdCV element constrains a fixed point on a body to slide along a curve that passes through the origins of a specified set of markers.
  - Constraint: PTdSF
    Model ElementThe Constraint_PTdSF element constrains a fixed point on a body to slide along a surface that passes through the origins of a specified set of markers.
  - Constraint: PTSF
    Model ElementConstraint_PTSF defines a higher pair constraint. A fixed point on one body slides on a surface that is fixed on a second body. The point is not allowed to lift off the surface.
  - Constraint: SFSF
    Model ElementConstraint_SFSF defines a higher pair constraint. The constraint consists of a surface on one body rolling and sliding on a surface on a second body. The surfaces are required to have a unique contact point.
  - Constraint: User
    Model ElementThe Constraint_UserConstr element is used to specify a user defined constraint. Your constraint equations may involve the configuration as well as velocity of the system.
  - Control: Differential Equation
    Model ElementControl_Diff defines a single, first order, user-defined differential equation in MotionSolve. A single, dynamic state is associated with the differential equation. This state is integrated along with the rest of the system states.
  - Control: FMU
    Model ElementFMU (Functional Mock-up Unit) is an abstract modeling entity that defines a generic modeling element in MotionSolve.
  - Control: Plant Input
    Model ElementThe Control_PlantInput element defines the inputs to a mechanical system or plant.
  - Control: Plant Output
    Model ElementThe Control_PlantOutput element defines the outputs from a mechanical system or plant.
  - Control: SISO
    Model ElementControl_SISO is an abstract modeling element that defines a linear, time invariant dynamic system in the Laplace domain. SISO stands for Single Input Single Output.
  - Control: State Equation
    Model ElementControl_StateEqn is an abstract modeling element that defines a generic dynamic system. The dynamic system is characterized by a vector of inputs u, a vector of dynamic states x, and a vector of outputs y. The state vector x is defined through a set of differential equations.
  - Force: Beam
    Model ElementForce_Beam defines a straight, massless beam of uniform cross section acting between two Reference_Markers, I and J that belong to two different bodies.
  - Force: Bushing
    Model ElementForce_Bushing defines a linear force and torque acting between two Reference_Markers, I and J.
  - Force: Contact
    Model ElementForce_Contact defines a 2D or 3D contact force between two bodies.
  - Force: DCVCV
    Model ElementThe Force: DCVCV element defines a contact force between two deformable curves.
  - Force: DCVSF
    Model ElementThe Force: DCVSF element defines a contact force between a deformable curve and deformable surface.
  - Force: DSFSF
    Model ElementThe Force: DSFSF element defines a contact force between two deformable surfaces.
  - Force: Field
    Model ElementForce_Field defines a force and torque acting between two Reference_Markers, I and J.
  - Force: FlexModal
    Model ElementForce_FlexModal defines a distributed force on a flexible body.
  - Force: Frequency Dependent
    Model ElementForce: Frequency Dependent defines a frequency dependent force and/or torque acting on a Reference_Marker.
  - Force: GRADCV
    Model ElementThe Force: GRADCV element defines a contact force between a deformable curve and graphic.
  - Force: GRADSF
    Model ElementThe Force: GRADSF element defines a contact force between a deformable surface and graphic.
  - Force: Gravity
    Model ElementForce_Gravity defines the acceleration due to gravity along the global X, Y, and Z directions.
  - Force: Joint Friction
  - Force: Multi-Point
    Model ElementForce_MultiPoint defines a force and torque acting between many Reference_Markers.
  - Force: One Body Vector
    Model ElementForce_Vector_OneBody defines a general force and/or torque acting on a Reference_Marker.
  - Force: Penalty
    Model ElementForce_Penalty defines a generalized force whose purpose is to maintain a "soft" constraint in the system.
  - Force: PTdCV
    Model ElementThe Force: PTdCV element defines a contact force between a deformable curve and point.
  - Force: PTdSF
    Model ElementThe Force_PTdSF element defines a contact force between a deformable surface and point.
  - Force: Spring Damper
    Model ElementForce_SpringDamper defines a spring damper force acting between two Reference_Markers.
  - Force: State Equation
    Model ElementForce_StateEqn is an abstract modeling element that combines the modeling capabilities of the Control_StateEqn and the Force_Vector_TwoBody model elements.
  - Force: Two Body Scalar
    Model ElementForce_Scalar_TwoBody defines a force or torque acting between two Reference_Markers.
  - Force: Two Body Vector
    Model ElementForce_Vector_TwoBody defines a general force and/or torque acting between two Reference_Markers.
  - Joint Initial Velocity: Cylindrical
    Model ElementThe JointInitialvel_Cyl element defines the initial velocity for a cylindrical joint element. It allows you to specify the initial velocities for both the translational and the rotational degree of freedom.
  - Joint Initial Velocity: Revolute
    Model ElementThe Jointlnitialvel_Rev element defines the initial angular velocity for a revolute joint element.
  - Joint Initial Velocity: Translational
    Model ElementThe JointInitialvel_Trans element defines the initial translational velocity for a translational joint element.
  - Messaging
    Model ElementThe Messaging element allows you to control how MotionSolve generates messages.
  - Motion: Joint Based
    Model ElementMotion_Joint defines a motion input at a degree-of-freedom in a joint.
  - Motion: Marker Based
    Model ElementMotion_Marker defines a motion input between two Reference_Markers.
  - Parameters: Linear Solver
    Model ElementParam_Linear defines the solution control parameters for a linear analysis. These parameters control the types of linear analyses to be done and the output options.
  - Parameters: Simulation
    Model ElementParam_Simulation defines the solution control parameters for simulations that are associated with more than one analysis method. Exceptions are noted.
  - Parameters: Static Solver
    Model ElementDefines the solution control parameters for static and quasi-static analysis, where the parameters control the accuracy of the solution and the method to be used for solution.
  - Parameters: Transient Solver
    Model ElementParam_Transient defines the simulation control parameters for a time-domain-based nonlinear dynamic analysis.
  - Parameters: Units
    Model ElementParam_Unit defines the units for the model being defined.
  - Point Mass
    Model ElementBody_Point defines a point mass entity in MotionSolve.
  - Post: Graphic
    Model ElementPost_Graphic defines a graphic element that can be used for visualization and also for 3D body contact.
  - Post: Output Request
    Model ElementPOST_REQUEST defines an output request entity in MotionSolve. POST_REQUESTs are written to MotionSolve output files so that they may be used for plotting and signal processing by HyperGraph and HyperGraph 3D.
  - Post: User Output Request
    Model ElementThe Post_UserAPI element allows you to generate your own results file. You can only have one Post_UserAPI without an ID. Use Post_UserAPIS to have more than one Post_UserAPI.
  - Post: User Outputs Request
    Model ElementThe Post_UserAPIS element allows you to generate your own results file. Post_UserAPIS supports more than one Post_UserAPI with an ID.
  - Reference: 2DCluster
    Model ElementA Reference_2DCluster specifies that a given set of bodies be constrained to move in one of the three principal planes: XY, YZ, or ZX.
  - Reference: Array
    Model ElementThe Reference_Array model statement specifies a list of variables (which are used by other MotionSolve modeling elements) or constants.
  - Reference: Deformable Curve
    Model ElementReference_DeformCurve specifies a deformable curve that is made to pass through the origins of a specified set of markers, using CUBIC spline interpolation. These markers may be on separate bodies. As the markers move in space, the curve shape is recalculated using CUBIC spline interpolation, thereby allowing the curve to deform.
  - Reference: Deformable Surface
    Model ElementReference_DeformSurface element specifies a deformable surface that is made to pass through the origins of a specified set of markers, using CUBIC spline interpolation.
  - Reference: Flexible Body Data
    Model ElementReference_FlexData contains the condensed representation of the flexibility characteristics of a flexible body. The flexibility data is calculated using a finite element solver, where the complete finite element model is available.
  - Reference: FrequencyInput
    Model ElementA Reference_FrequencyInput defines the input to the frequency response analysis.
  - Reference: Marker
    Model ElementA Reference_Marker defines an orthonormal, right-handed coordinate system and reference frame in MotionSolve. A Reference_Marker must belong to a body. The body can be any type: rigid, flexible, or point.
  - Reference: Matrix
    Model ElementReference_Matrix defines a general, real-valued, M x N matrix for use in MotionSolve.
  - Reference: Parametric Curve
    Model ElementReference_ParamCurve defines a parametric curve element. A parametric curve is defined in terms of one free parameter, u. Referring to the image below, assume a curve C is defined with respect to a coordinate system OXYZ.
  - Reference: Parametric Surface
    Model ElementReference_ParamSurface defines a parametric surface element. A parametric surface is defined in terms of two free parameters: u and v. Referring to the image below, assume a surface S is defined with respect to a coordinate system OXYZ.
  - Reference: PlantState
    Model ElementReference_PlantState defines a list of user-defined states used in generating a linear representation of a model about an operating point. The linear representation is used for both eigenvalue analysis and state matrix generation.
  - Reference: Solver Variable
    Model ElementReference_Variable defines an algebraic state in MotionSolve.
  - Reference: Spline
    Model ElementReference_Spline defines a spline with one or two independent variables.
  - Reference: String
    Model ElementReference_String defines a user defined text string in MotionSolve. The string may be of any length. It must contain only printable ASCII characters.
  - Sensor: Evaluate
    Model ElementA Sensor_Evaluate element is always associated with one or more Sensor_Event modeling elements. When a Sensor_Event becomes "active", a Sensor_Evaluate may be optionally called to define a scalar value based on the current value of the system states. This value is not re-evaluated until one of the parent Sensor_Event's becomes active again.
  - Sensor: Event
    Model ElementThis model element defines an event sensor in the model.
  - Sensor: Proximity
    Model ElementThe Sensor_Proximity element defines a sensor that measures the minimum distance between the graphics/mesh of two bodies. The sensor tracks the state of interference of the graphics/mesh, the length of the minimum distance, and the coordinates of a pair of closest points. These quantities can be accessed using the PROXIMITY function for use in defining expressions or for plotting.
  - Subsystem: Planar
    Model ElementA Subsystem_Planar element aggregates a collection of Reference_2DCluster elements.
- Functions
- The Subroutine Interface for MotionSolve
- ADM/ACF Entities
- NLFE Statements
- msolve API Statements

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Force: Gravity

Model ElementForce_Gravity defines the acceleration due to gravity along the global X, Y, and Z directions.

Format

<Force_Gravity

     grav_x = "real" 
    
     grav_y = "real"     

     grav_z = "real" >
/>

Attributes

grav_x: Defines the acceleration due to gravity in the global X direction. The default value is 0.0.
grav_y: Defines the acceleration due to gravity in the global Y direction. The default value is 0.0.
grav_z: Defines the acceleration due to gravity in the global X direction. The default value is 0.0.

Example

The example below shows the gravity components in SI units.

<Force_Gravity
     grav_x = "0."
     grav_y = "0."
     grav_z = "-9810."
/>

The following example shows gravity components modeled as a function of time.

<Force_Gravity
     grav_x = "9810*STEP(TIME,0,0,2,1)"
     grav_y = "0."
     grav_z = "-9810*STEP(TIME,0,1,2,0)"
/>

Comments

grav_x, grav_y, grav_z may be specified as real numbers or as function expressions. This allows you to model gravity as a function of time. If gravity is modeled as a function of displacements, forces or other states of the system, MotionSolve may have difficulty finding a converged solution.
To represent state dependent gravity effects, use Force_Vector_TwoBody.
The dimension of acceleration due gravity is: L T^-2.