Add Translational library similar to MSL (#151)

* Add Translational library similar to MSL

* add tests

* fix tests

* add partial and constant torque soruces

* rm tau from InternalSupport state variables

* format

* add docs and tests for constant torque

Author: baggepinnen

src/Mechanical/Mechanical.jl

@@ -8,6 +8,7 @@ using ModelingToolkit
 include("Rotational/Rotational.jl")
 include("Translational/Translational.jl")
 include("TranslationalPosition/TranslationalPosition.jl")
+include("TranslationalModelica/TranslationalModelica.jl")
 include("MultiBody2D/MultiBody2D.jl")
 
 end

src/Mechanical/Rotational/Rotational.jl

@@ -15,7 +15,7 @@ include("utils.jl")
 export Fixed, Inertia, Spring, Damper, IdealGear, RotationalFriction
 include("components.jl")
 
-export Torque, Speed
+export Torque, ConstantTorque, Speed
 include("sources.jl")
 
 export AngleSensor, SpeedSensor, TorqueSensor, RelSpeedSensor

src/Mechanical/Rotational/sources.jl

@@ -1,11 +1,22 @@
+
+function PartialTorque(; name, use_support = false)
+    @named partial_element = PartialElementaryOneFlangeAndSupport2(use_support = use_support)
+    @unpack flange, phi_support = partial_element
+    @variables phi(t) [
+        description = "Angle of flange with respect to support (= flange.phi - support.phi)",
+    ]
+    eqs = [phi ~ flange.phi - phi_support]
+    return extend(ODESystem(eqs, t; name = name), partial_element)
+end
+
 """
     Torque(; name, use_support=false)
 
 Input signal acting as external torque on a flange
 
 # States:
 
-  - `phi_support(t)`: [`rad`] Absolute angle of support flange"
+  - `phi_support(t)`: [`rad`] Absolute angle of support flange
 
 # Connectors:
 
@@ -25,7 +36,41 @@ Input signal acting as external torque on a flange
 end
 
 """
-    Speed(; name, use_support=false, exact=false, f_crit=50)
+    ConstantTorque(; name, tau_constant, use_support = false)
+
+Constant torque source
+
+# State variables:
+  
+- `phi_support(t)`: [`rad`] Absolute angle of support flange, only available if `use_support = true`
+- `tau`: Accelerating torque acting at flange (= -flange.tau)
+- `w`: Angular velocity of flange with respect to support (= der(phi))
+
+# Connectors:
+- `flange` [Flange](@ref)
+
+# Arguments:
+- `tau_constant`: The constant torque applied by the source
+- `use_support`: Whether or not an internal support flange is added, defaults to false.
+"""
+function ConstantTorque(; name, tau_constant, use_support = false)
+    @named partial_element = PartialTorque(; use_support)
+    @unpack flange, phi = partial_element
+    @parameters tau_constant=tau_constant [
+        description = "Constant torque (if negative, torque is acting as load in positive direction of rotation)",
+    ]
+    @variables tau(t) [description = "Accelerating torque acting at flange (= -flange.tau)"]
+    @variables w(t) [
+        description = "Angular velocity of flange with respect to support (= der(phi))",
+    ]
+    eqs = [w ~ D(phi)
+           tau ~ -flange.tau
+           tau ~ tau_constant]
+    return extend(ODESystem(eqs, t; name = name), partial_element)
+end
+
+"""
+    Speed(; name, use_support=false, exact=false, f_crit=50) 
 
 Forced movement of a flange according to a reference angular velocity signal
 

src/Mechanical/Rotational/utils.jl

@@ -4,7 +4,7 @@
     ODESystem(Equation[], t, sts, [], name = name, defaults = Dict(phi => 0.0, tau => 0.0))
 end
 Base.@doc """
-    Flange(;name)
+    Support(;name)
 
 1-dim. rotational flange of a shaft.
 
@@ -14,10 +14,31 @@ Base.@doc """
 """ Flange
 
 @connector function Support(; name)
-    sts = @variables(phi(t), [description = "Rotation angle of support $name"],
-                     tau(t), [connect = Flow, description = "Cut torque in support $name"],)
-    ODESystem(Equation[], t, sts, [], name = name, defaults = Dict(phi => 0.0, tau => 0.0))
+    @named flange = Flange()
+    extend(ODESystem(Equation[], t, [], [], name = name), flange)
 end
+
+# Base.@doc """
+#     InternalSupport(;name, tau)
+
+# 1-dim. rotational flange of a shaft.
+
+# - `tau`: External support torque (must be computed via torque balance in model where InternalSupport is used; = flange.tau)
+
+# # States:
+# - `phi(t)`: [`rad`] Absolute rotation angle of flange
+# - `tau(t)`: [`N.m`] Cut torque in the flange
+# """ Flange
+
+# @connector function InternalSupport(; name, tau)
+#     @named flange = Flange()
+#     @variables phi(t)=0 [description = "Rotation angle of support $name"]
+#     # tau(t), [connect = Flow, description = "Cut torque in support $name"],)
+#     equations = [flange.tau ~ tau
+#                  flange.phi ~ phi]
+#     ODESystem(equations, t, [phi], [], name = name, systems = [flange]) # NOTE: tau not included since it belongs elsewhere
+# end
+
 Base.@doc """
     Support(;name)
 

src/Mechanical/TranslationalModelica/TranslationalModelica.jl

@@ -0,0 +1,21 @@
+"""
+Library to model 1-dimensional, translational mechanical components.
+"""
+module TranslationalModelica
+
+using ModelingToolkit, Symbolics, IfElse
+using ...Blocks: RealInput, RealOutput
+
+@parameters t
+D = Differential(t)
+
+export Flange
+include("utils.jl")
+
+export Fixed, Mass, Spring, Damper, IdealGear
+include("components.jl")
+
+export Force
+include("sources.jl")
+
+end

src/Mechanical/TranslationalModelica/components.jl

@@ -0,0 +1,104 @@
+"""
+    Fixed(;name, s0=0.0)
+
+Flange fixed in housing at a given position.
+
+# Parameters:
+
+  - `s0`: [m] Fixed offset position of housing
+
+# Connectors:
+
+  - `flange: 1-dim. translational flange`
+"""
+function Fixed(; name, s0 = 0.0)
+    pars = @parameters s0 = s0
+    vars = []
+
+    @named flange = Flange()
+
+    eqs = [flange.s ~ s0]
+
+    return compose(ODESystem(eqs, t, vars, pars; name = name, defaults = [flange.s => s0]),
+                   flange)
+end
+
+"""
+    Mass(; name, m, s0 = 0.0, v0 = 0.0)
+
+Sliding mass with inertia
+
+# Parameters:
+
+  - `m`: [kg] Mass of sliding mass
+  - `s0`: [m] Initial value of absolute position of sliding mass
+  - `v0`: [m/s] Initial value of absolute linear velocity of sliding mass
+
+# States:
+
+  - `s`: [m] Absolute position of sliding mass
+  - `v`: [m/s] Absolute linear velocity of sliding mass (= D(s))
+
+# Connectors:
+
+  - `flange: 1-dim. translational flange of mass`
+"""
+function Mass(m; name, s0 = 0.0, v0 = 0.0)
+    @named pr = PartialRigid(; L = 0, s0)
+    @unpack flange_a, flange_b, s = pr
+    @parameters m=m [description = "Mass of sliding mass [kg]"]
+    @variables v(t)=v0 [description = "Absolute linear velocity of sliding mass [m/s]"]
+    @variables a(t)=0 [description = "Absolute linear acceleration of sliding mass [m/s^2]"]
+    eqs = [v ~ D(s)
+           a ~ D(v)
+           m * a ~ flange_a.f + flange_b.f]
+    return extend(ODESystem(eqs, t; name), pr)
+end
+
+"""
+    Spring(c; name, s_rel0=0)
+
+Linear 1D translational spring
+
+# Parameters:
+
+  - `c`: [N/m] Spring constant
+  - `s_rel0`: Unstretched spring length
+
+# Connectors:
+
+  - `flange_a: 1-dim. translational flange on one side of spring`
+  - `flange_b: 1-dim. translational flange on opposite side of spring` #default function
+"""
+function Spring(c; name, s_rel0 = 0)
+    @named pc = PartialCompliant()
+    @unpack flange_a, flange_b, s_rel, f = pc
+    @parameters c=c [description = "Spring constant [N/m]"]
+    @parameters s_rel0=s_rel0 [description = "Unstretched spring length [m]"]
+
+    eqs = [f ~ c * (s_rel - s_rel0)]
+    return extend(ODESystem(eqs, t; name), pc)
+end
+
+"""
+    Damper(d; name)
+
+Linear 1D translational damper
+
+# Parameters:
+
+  - `d`: [N.s/m] Damping constant
+
+# Connectors:
+
+  - `flange_a: 1-dim. translational flange on one side of damper`
+  - `flange_b: 1-dim. translational flange on opposite side of damper`
+"""
+function Damper(d; name)
+    @named pc = PartialCompliantWithRelativeStates()
+    @unpack flange_a, flange_b, v_rel, f = pc
+    @parameters d=d [description = "Damping constant [Ns/m]"]
+    @variables lossPower(t)=0 [description = "Power dissipated by the damper [W]"]
+    eqs = [f ~ d * v_rel; lossPower ~ f * v_rel]
+    return extend(ODESystem(eqs, t; name), pc)
+end

src/Mechanical/TranslationalModelica/sources.jl

@@ -0,0 +1,12 @@
+"""
+    Force(;name) 
+
+Input signal acting as external force on a flange
+"""
+function Force(; name, use_support = false)
+    @named partial_element = PartialElementaryOneFlangeAndSupport2(use_support = use_support)
+    @unpack flange = partial_element
+    @named f = RealInput() # Accelerating force acting at flange (= -flange.tau)
+    eqs = [flange.f ~ -f.u]
+    return extend(ODESystem(eqs, t, [], []; name = name, systems = [f]), partial_element)
+end