LIBRARY

tests.GearConstraintTest

Gear Constraint Test

Ported from the Multibody.jl GearConstraint test (basic_tests.jl). Two parallel subsystems with the same 10:1 gear ratio:

• 3D side: a GearConstraint couples two Body instances mounted on the world via the constraint's bearing frame; a 3D Torque applies [2*sin(t), 0, 0] between world and the first body.

• 1D side: a 1D IdealGear between two Inertia instances (with the same J as the bodies), driven by a 1D torque source 2*sin(t).

Both subsystems should follow the gear-ratio relation, so the angles and torques on either side of the 1D gear differ by a factor of ratio.

Usage

MultibodyComponents.tests.GearConstraintTest(ratio=10, J=0.001)

Parameters:

Name	Description	Units	Default value
ratio		–	10
J		kg.m2	0.001

Behavior

Source

"""
# Gear Constraint Test

Ported from the Multibody.jl GearConstraint test (basic_tests.jl).
Two parallel subsystems with the same 10:1 gear ratio:

- 3D side: a `GearConstraint` couples two `Body` instances mounted on the
  world via the constraint's `bearing` frame; a 3D `Torque` applies
  `[2*sin(t), 0, 0]` between world and the first body.
- 1D side: a 1D `IdealGear` between two `Inertia` instances (with the same
  `J` as the bodies), driven by a 1D torque source `2*sin(t)`.

Both subsystems should follow the gear-ratio relation, so the angles and
torques on either side of the 1D gear differ by a factor of `ratio`.
"""
example component GearConstraintTest
  # Common world
  world = MultibodyComponents.World() {}
  # 3D gear-constraint subsystem
  gear = MultibodyComponents.GearConstraint(ratio = ratio, n_a = [1, 0, 0], n_b = [1, 0, 0], phi_b(initial = 0), w_b(initial = 0)) {}
  cyl1 = MultibodyComponents.Body(m = 1, r_cm = [0.4, 0, 0], I_11 = J) {}
  cyl2 = MultibodyComponents.Body(m = 1, r_cm = [0.4, 0, 0], I_11 = J) {}
  torque1 = MultibodyComponents.Torque(resolve_in_frame = ResolveInFrame.FrameB()) {}
  # 1D rotational subsystem (mirror of the 3D side)
  inertia1 = RotationalComponents.Components.Inertia(J = J) {}
  ideal_gear = RotationalComponents.Components.IdealGear(ratio = ratio) {}
  inertia2 = RotationalComponents.Components.Inertia(J = J) {}
  torque2 = RotationalComponents.Sources.TorqueSource() {}
  rot_ground = RotationalComponents.Components.Fixed() {}
  parameter ratio::Real = 10
  parameter J::Inertia = 0.001
relations
  initial inertia1.phi = 0
  initial inertia1.w = 0
  # 3D side
  connect(world.frame_b, gear.bearing) {}
  connect(gear.frame_a, cyl1.frame_a, torque1.frame_b) {}
  connect(gear.frame_b, cyl2.frame_a) {}
  connect(world.frame_b, torque1.frame_a) {}
  torque1.torque_x = 2 * sin(time)
  torque1.torque_y = 0
  torque1.torque_z = 0
  # 1D side
  connect(torque2.spline, inertia1.spline_a) {}
  connect(inertia1.spline_b, ideal_gear.spline_a) {}
  connect(ideal_gear.spline_b, inertia2.spline_a) {}
  connect(rot_ground.spline, ideal_gear.support, torque2.support) {}
  torque2.tau = 2 * sin(time)
end

Flattened Source

"""
# Gear Constraint Test

Ported from the Multibody.jl GearConstraint test (basic_tests.jl).
Two parallel subsystems with the same 10:1 gear ratio:

- 3D side: a `GearConstraint` couples two `Body` instances mounted on the
  world via the constraint's `bearing` frame; a 3D `Torque` applies
  `[2*sin(t), 0, 0]` between world and the first body.
- 1D side: a 1D `IdealGear` between two `Inertia` instances (with the same
  `J` as the bodies), driven by a 1D torque source `2*sin(t)`.

Both subsystems should follow the gear-ratio relation, so the angles and
torques on either side of the 1D gear differ by a factor of `ratio`.
"""
example component GearConstraintTest
  # Common world
  world = MultibodyComponents.World() {}
  # 3D gear-constraint subsystem
  gear = MultibodyComponents.GearConstraint(ratio = ratio, n_a = [1, 0, 0], n_b = [1, 0, 0], phi_b(initial = 0), w_b(initial = 0)) {}
  cyl1 = MultibodyComponents.Body(m = 1, r_cm = [0.4, 0, 0], I_11 = J) {}
  cyl2 = MultibodyComponents.Body(m = 1, r_cm = [0.4, 0, 0], I_11 = J) {}
  torque1 = MultibodyComponents.Torque(resolve_in_frame = ResolveInFrame.FrameB()) {}
  # 1D rotational subsystem (mirror of the 3D side)
  inertia1 = RotationalComponents.Components.Inertia(J = J) {}
  ideal_gear = RotationalComponents.Components.IdealGear(ratio = ratio) {}
  inertia2 = RotationalComponents.Components.Inertia(J = J) {}
  torque2 = RotationalComponents.Sources.TorqueSource() {}
  rot_ground = RotationalComponents.Components.Fixed() {}
  parameter ratio::Real = 10
  parameter J::Inertia = 0.001
relations
  initial inertia1.phi = 0
  initial inertia1.w = 0
  # 3D side
  connect(world.frame_b, gear.bearing) {}
  connect(gear.frame_a, cyl1.frame_a, torque1.frame_b) {}
  connect(gear.frame_b, cyl2.frame_a) {}
  connect(world.frame_b, torque1.frame_a) {}
  torque1.torque_x = 2 * sin(time)
  torque1.torque_y = 0
  torque1.torque_z = 0
  # 1D side
  connect(torque2.spline, inertia1.spline_a) {}
  connect(inertia1.spline_b, ideal_gear.spline_a) {}
  connect(ideal_gear.spline_b, inertia2.spline_a) {}
  connect(rot_ground.spline, ideal_gear.support, torque2.support) {}
  torque2.tau = 2 * sin(time)
metadata {}
end

Test Cases

No test cases defined.

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