WOLFRAM SYSTEMMODELER

Revolute

Revolute joint (1 rotational degree-of-freedom, 2 potential states, optional axis flange)

Diagram

Wolfram Language

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Click for copyable input
SystemModel["Modelica.Mechanics.MultiBody.Joints.Revolute"]
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Information

This information is part of the Modelica Standard Library maintained by the Modelica Association.

Joint where frame_b rotates around axis n which is fixed in frame_a. The two frames coincide when the rotation angle "phi = 0".

Optionally, two additional 1-dimensional mechanical flanges (flange "axis" represents the driving flange and flange "support" represents the bearing) can be enabled via parameter useAxisFlange. The enabled axis flange can be driven with elements of the Modelica.Mechanics.Rotational library.

In the "Advanced" menu it can be defined via parameter stateSelect that the rotation angle "phi" and its derivative shall be definitely used as states by setting stateSelect=StateSelect.always. Default is StateSelect.prefer to use the joint angle and its derivative as preferred states. The states are usually selected automatically. In certain situations, especially when closed kinematic loops are present, it might be slightly more efficient, when using the StateSelect.always setting.

If a planar loop is present, e.g., consisting of 4 revolute joints where the joint axes are all parallel to each other, then there is no longer a unique mathematical solution and the symbolic algorithms will fail. Usually, an error message will be printed pointing out this situation. In this case, one revolute joint of the loop has to be replaced by a Joints.RevolutePlanarLoopConstraint joint. The effect is that from the 5 constraints of a usual revolute joint, 3 constraints are removed and replaced by appropriate known variables (e.g., the force in the direction of the axis of rotation is treated as known with value equal to zero; for standard revolute joints, this force is an unknown quantity).

In the following figure the animation of a revolute joint is shown. The light blue coordinate system is frame_a and the dark blue coordinate system is frame_b of the joint. The black arrow is parameter vector "n" defining the translation axis (here: n = {0,0,1}, phi.start = 45o).

Connectors (4)

axis

Type: Flange_a

Description: 1-dim. rotational flange that drives the joint

support

Type: Flange_b

Description: 1-dim. rotational flange of the drive support (assumed to be fixed in the world frame, NOT in the joint)

frame_a

Type: Frame_a

Description: Coordinate system fixed to the joint with one cut-force and cut-torque

frame_b

Type: Frame_b

Description: Coordinate system fixed to the joint with one cut-force and cut-torque

Parameters (7)

useAxisFlange

Value: false

Type: Boolean

Description: = true, if axis flange is enabled

animation

Value: true

Type: Boolean

Description: = true, if animation shall be enabled (show axis as cylinder)

n

Value: {0, 0, 1}

Type: Axis ()

Description: Axis of rotation resolved in frame_a (= same as in frame_b)

cylinderLength

Value: world.defaultJointLength

Type: Distance (m)

Description: Length of cylinder representing the joint axis

cylinderDiameter

Value: world.defaultJointWidth

Type: Distance (m)

Description: Diameter of cylinder representing the joint axis

stateSelect

Value: StateSelect.prefer

Type: StateSelect

Description: Priority to use joint angle phi and w=der(phi) as states

e

Value: Modelica.Math.Vectors.normalizeWithAssert(n)

Type: Real[3] ()

Description: Unit vector in direction of rotation axis, resolved in frame_a (= same as in frame_b)

Components (6)

world

Type: World

Description:

R_rel

Type: Orientation

Description: Relative orientation object from frame_a to frame_b or from frame_b to frame_a

cylinder

Type: Shape

Description:

fixed

Type: Fixed

Description: support flange is fixed to ground

internalAxis

Type: InternalSupport

Description:

constantTorque

Type: ConstantTorque

Description:

Used in Examples (22)

DoublePendulum

Simple double pendulum with two revolute joints and two bodies

DoublePendulumInitTip

Demonstrate how to initialize a double pendulum so that its tip starts at a predefined position

ForceAndTorque

Demonstrate usage of ForceAndTorque element

InitSpringConstant

Determine spring constant such that system is in steady state at given position

LineForceWithTwoMasses

Demonstrate line force with two point masses using a JointUPS and alternatively a LineForceWithTwoMasses component

Pendulum

Simple pendulum with one revolute joint and one body

PendulumWithSpringDamper

Simple spring/damper/mass system

UserDefinedGravityField

Demonstrate the modeling of a user-defined gravity field

Engine1a

Model of one cylinder engine

Engine1b

Model of one cylinder engine with gas force and preparation for assembly joint JointRRP

Engine1b_analytic

Model of one cylinder engine with gas force and analytic loop handling

EngineV6

V6 engine with 6 cylinders, 6 planar loops and 1 degree-of-freedom

Fourbar1

One kinematic loop with four bars (with only revolute joints; 5 non-linear equations)

Fourbar2

One kinematic loop with four bars (with UniversalSpherical joint; 1 non-linear equation)

Fourbar_analytic

One kinematic loop with four bars (with JointSSP joint; analytic solution of non-linear algebraic loop)

PlanarLoops_analytic

Mechanism with three planar kinematic loops and one degree-of-freedom with analytic loop handling (with JointRRR joints)

Engine1bBase

Model of one cylinder engine with gas force

GyroscopicEffects

Demonstrates that a cylindrical body can be replaced by Rotor1D model

ActuatedDrive

Demonstrates usage of models Rotor1D and Mounting1D

MovingActuatedDrive

Demonstrates usage of model Rotor1D mounted on a moving body

BevelGear1D

Demonstrates the usage of a BevelGear1D model and how to calculate the power of such an element

RevoluteConstraint

Body attached by one spring and revolute joint or constrained to environment

Used in Components (8)

Cylinder

Cylinder with rod and crank of a combustion engine

EngineV6_analytic

V6 engine with analytic loop handling

MechanicalStructure

Model of the mechanical part of the r3 robot (without animation)

Cylindrical

Cylindrical joint (2 degrees-of-freedom, 4 potential states)

Universal

Universal joint (2 degrees-of-freedom, 4 potential states)

Planar

Planar joint (3 degrees-of-freedom, 6 potential states)

GearConstraint

Ideal 3-dim. gearbox (arbitrary shaft directions)

RollingWheelSet

Joint (no mass, no inertia) that describes an ideal rolling wheel set (two ideal rolling wheels connected together by an axis)