Revolute

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

Diagram

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 = 45^o).

Parameters (6)

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

Inputs (2)

cylinderColor	Default Value: Modelica.Mechanics.MultiBody.Types.Defaults.JointColor Type: Color Description: Color of cylinder representing the joint axis
specularCoefficient	Default Value: world.defaultSpecularCoefficient Type: SpecularCoefficient Description: Reflection of ambient light (= 0: light is completely absorbed)

cylinderColor

Default Value: Modelica.Mechanics.MultiBody.Types.Defaults.JointColor

Type: Color

Description: Color of cylinder representing the joint axis

specularCoefficient

Default Value: world.defaultSpecularCoefficient

Type: SpecularCoefficient

Description: Reflection of ambient light (= 0: light is completely absorbed)

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

Components (6)

	world	Type: World
	R_rel	Type: Orientation Description: Relative orientation object from frame_a to frame_b or from frame_b to frame_a
	cylinder	Type: Shape
	fixed	Type: Fixed Description: support flange is fixed to ground
	internalAxis	Type: InternalSupport
	constantTorque	Type: ConstantTorque

Used in Examples (21)

	DoublePendulum Modelica.Mechanics.MultiBody.Examples.Elementary Simple double pendulum with two revolute joints and two bodies
	DoublePendulumInitTip Modelica.Mechanics.MultiBody.Examples.Elementary Demonstrate how to initialize a double pendulum so that its tip starts at a predefined position
	ForceAndTorque Modelica.Mechanics.MultiBody.Examples.Elementary Demonstrate usage of ForceAndTorque element
	InitSpringConstant Modelica.Mechanics.MultiBody.Examples.Elementary Determine spring constant such that system is in steady state at given position
	LineForceWithTwoMasses Modelica.Mechanics.MultiBody.Examples.Elementary Demonstrate line force with two point masses using a JointUPS and alternatively a LineForceWithTwoMasses component
	Pendulum Modelica.Mechanics.MultiBody.Examples.Elementary Simple pendulum with one revolute joint and one body
	PendulumWithSpringDamper Modelica.Mechanics.MultiBody.Examples.Elementary Simple spring/damper/mass system
	UserDefinedGravityField Modelica.Mechanics.MultiBody.Examples.Elementary Demonstrate the modeling of a user-defined gravity field
	Engine1a Modelica.Mechanics.MultiBody.Examples.Loops Model of one cylinder engine
	Engine1b Modelica.Mechanics.MultiBody.Examples.Loops Model of one cylinder engine with gas force and preparation for assembly joint JointRRP
	EngineV6 Modelica.Mechanics.MultiBody.Examples.Loops V6 engine with 6 cylinders, 6 planar loops and 1 degree-of-freedom
	Fourbar1 Modelica.Mechanics.MultiBody.Examples.Loops One kinematic loop with four bars (with only revolute joints; 5 non-linear equations)
	Fourbar2 Modelica.Mechanics.MultiBody.Examples.Loops One kinematic loop with four bars (with UniversalSpherical joint; 1 non-linear equation)
	Fourbar_analytic Modelica.Mechanics.MultiBody.Examples.Loops One kinematic loop with four bars (with JointSSP joint; analytic solution of non-linear algebraic loop)
	PlanarFourbar Modelica.Mechanics.MultiBody.Examples.Loops Planar four bars mechanism with one kinematic loop (with RevolutePlanarLoopConstraint joint)
	PlanarLoops_analytic Modelica.Mechanics.MultiBody.Examples.Loops Mechanism with three planar kinematic loops and one degree-of-freedom with analytic loop handling (with JointRRR joints)
	GyroscopicEffects Modelica.Mechanics.MultiBody.Examples.Rotational3DEffects Demonstrates that a cylindrical body can be replaced by Rotor1D model
	ActuatedDrive Modelica.Mechanics.MultiBody.Examples.Rotational3DEffects Demonstrates usage of models Rotor1D and Mounting1D
	MovingActuatedDrive Modelica.Mechanics.MultiBody.Examples.Rotational3DEffects Demonstrates usage of model Rotor1D mounted on a moving body
	BevelGear1D Modelica.Mechanics.MultiBody.Examples.Rotational3DEffects Demonstrates the usage of a BevelGear1D model and how to calculate the power of such an element
	RevoluteConstraint Modelica.Mechanics.MultiBody.Examples.Constraints Body attached by one spring and revolute joint or constrained to environment

Used in Components (9)

	Cylinder Modelica.Mechanics.MultiBody.Examples.Loops.Utilities Cylinder with rod and crank of a combustion engine
	EngineV6_analytic Modelica.Mechanics.MultiBody.Examples.Loops.Utilities V6 engine with analytic loop handling
	Engine1bBase Modelica.Mechanics.MultiBody.Examples.Loops.Utilities Model of one cylinder engine with gas force
	MechanicalStructure Modelica.Mechanics.MultiBody.Examples.Systems.RobotR3.Components Model of the mechanical part of the r3 robot (without animation)
	Cylindrical Modelica.Mechanics.MultiBody.Joints Cylindrical joint (2 degrees-of-freedom, 4 potential states)
	Universal Modelica.Mechanics.MultiBody.Joints Universal joint (2 degrees-of-freedom, 4 potential states)
	Planar Modelica.Mechanics.MultiBody.Joints Planar joint (3 degrees-of-freedom, 6 potential states)
	GearConstraint Modelica.Mechanics.MultiBody.Joints Ideal 3-dim. gearbox (arbitrary shaft directions)
	RollingWheelSet Modelica.Mechanics.MultiBody.Joints Joint (no mass, no inertia) that describes an ideal rolling wheel set (two ideal rolling wheels connected together by an axis)