424 lines
13 KiB
Python
424 lines
13 KiB
Python
"""
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Electronic components
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"""
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from dataclasses import dataclass
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from typing import Optional, Tuple
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import math
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import cadquery as Cq
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from nhf.materials import Role
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from nhf.parts.item import Item
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from nhf.parts.fasteners import FlatHeadBolt, HexNut
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import nhf.utils
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import scipy.optimize as SO
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@dataclass(frozen=True)
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class LinearActuator(Item):
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stroke_length: float
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shaft_diam: float = 9.04
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front_hole_ext: float = 4.41
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front_hole_diam: float = 4.41
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front_length: float = 9.55
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front_width: float = 9.24
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front_height: float = 5.98
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segment1_length: float = 37.55
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segment1_width: float = 15.95
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segment1_height: float = 11.94
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segment2_length: float = 37.47
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segment2_width: float = 20.03
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segment2_height: float = 15.03
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back_hole_ext: float = 4.58
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back_hole_diam: float = 4.18
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back_length: float = 9.27
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back_width: float = 10.16
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back_height: float = 8.12
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@property
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def name(self) -> str:
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return f"LinearActuator {self.stroke_length}mm"
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@property
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def role(self) -> Role:
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return Role.MOTION
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@property
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def conn_length(self):
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return self.segment1_length + self.segment2_length + self.front_hole_ext + self.back_hole_ext
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def generate(self, pos: float=0) -> Cq.Assembly:
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assert -1e-6 <= pos <= 1 + 1e-6
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stroke_x = pos * self.stroke_length
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front = (
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Cq.Workplane('XZ')
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.cylinder(
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radius=self.front_width / 2,
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height=self.front_height,
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centered=True,
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)
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.box(
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length=self.front_hole_ext,
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width=self.front_width,
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height=self.front_height,
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combine=True,
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centered=(False, True, True)
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)
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.copyWorkplane(Cq.Workplane('XZ'))
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.cylinder(
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radius=self.front_hole_diam / 2,
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height=self.front_height,
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centered=True,
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combine='cut',
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)
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)
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front.copyWorkplane(Cq.Workplane('XZ')).tagPlane('conn')
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if stroke_x > 0:
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shaft = (
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Cq.Workplane('YZ')
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.cylinder(
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radius=self.shaft_diam / 2,
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height=stroke_x,
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centered=(True, True, False)
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)
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)
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else:
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shaft = None
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segment1 = (
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Cq.Workplane()
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.box(
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length=self.segment1_length,
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height=self.segment1_width,
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width=self.segment1_height,
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centered=(False, True, True),
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)
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)
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segment2 = (
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Cq.Workplane()
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.box(
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length=self.segment2_length,
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height=self.segment2_width,
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width=self.segment2_height,
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centered=(False, True, True),
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)
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)
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back = (
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Cq.Workplane('XZ')
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.cylinder(
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radius=self.back_width / 2,
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height=self.back_height,
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centered=True,
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)
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.box(
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length=self.back_hole_ext,
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width=self.back_width,
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height=self.back_height,
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combine=True,
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centered=(False, True, True)
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)
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.copyWorkplane(Cq.Workplane('XZ'))
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.cylinder(
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radius=self.back_hole_diam / 2,
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height=self.back_height,
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centered=True,
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combine='cut',
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)
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)
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back.copyWorkplane(Cq.Workplane('XZ')).tagPlane('conn')
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result = (
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Cq.Assembly()
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.add(front, name="front",
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loc=Cq.Location((-self.front_hole_ext, 0, 0)))
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.add(segment1, name="segment1",
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loc=Cq.Location((stroke_x, 0, 0)))
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.add(segment2, name="segment2",
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loc=Cq.Location((stroke_x + self.segment1_length, 0, 0)))
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.add(back, name="back",
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loc=Cq.Location((stroke_x + self.segment1_length + self.segment2_length + self.back_hole_ext, 0, 0), (0, 1, 0), 180))
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)
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if shaft:
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result.add(shaft, name="shaft")
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return result
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@dataclass(frozen=True)
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class MountingBracket(Item):
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"""
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Mounting bracket for a linear actuator
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"""
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mass: float = 1.6
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hole_diam: float = 4.0
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width: float = 8.0
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height: float = 12.20
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thickness: float = 0.98
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length: float = 13.00
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hole_to_side_ext: float = 8.10
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def __post_init__(self):
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assert self.hole_to_side_ext - self.hole_diam / 2 > 0
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@property
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def name(self) -> str:
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return f"MountingBracket M{int(self.hole_diam)}"
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@property
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def role(self) -> Role:
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return Role.MOTION
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def generate(self) -> Cq.Workplane:
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result = (
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Cq.Workplane('XY')
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.box(
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length=self.hole_to_side_ext,
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width=self.width,
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height=self.height,
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centered=(False, True, True)
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)
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.copyWorkplane(Cq.Workplane('XY'))
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.cylinder(
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height=self.height,
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radius=self.width / 2,
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combine=True,
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)
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.copyWorkplane(Cq.Workplane('XY'))
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.box(
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length=2 * (self.hole_to_side_ext - self.thickness),
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width=self.width,
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height=self.height - self.thickness * 2,
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combine='cut',
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)
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.copyWorkplane(Cq.Workplane('XY'))
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.cylinder(
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height=self.height,
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radius=self.hole_diam / 2,
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combine='cut'
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)
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.copyWorkplane(Cq.Workplane('YZ'))
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.cylinder(
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height=self.hole_to_side_ext * 2,
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radius=self.hole_diam / 2,
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combine='cut'
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)
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)
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result.copyWorkplane(Cq.Workplane('YZ', origin=(self.hole_to_side_ext, 0, 0))).tagPlane("conn_side")
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result.copyWorkplane(Cq.Workplane('XY', origin=(0, 0, self.height/2))).tagPlane("conn_top")
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result.copyWorkplane(Cq.Workplane('YX', origin=(0, 0, -self.height/2))).tagPlane("conn_bot")
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result.copyWorkplane(Cq.Workplane('XY')).tagPlane("conn_mid")
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return result
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@dataclass(frozen=True)
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class BatteryBox18650(Item):
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"""
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A number of 18650 batteries in series
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"""
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mass: float = 17.4 + 68.80 * 3
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length: float = 75.70
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width_base: float = 61.46 - 18.48 - 20.18 * 2
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battery_dist: float = 20.18
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height: float = 19.66
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# space from bottom to battery begin
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thickness: float = 1.66
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battery_diam: float = 18.48
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battery_height: float = 68.80
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n_batteries: int = 3
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def __post_init__(self):
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assert 2 * self.thickness < min(self.length, self.height)
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@property
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def name(self) -> str:
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return f"BatteryBox 18650*{self.n_batteries}"
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@property
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def role(self) -> Role:
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return Role.ELECTRONIC
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def generate(self) -> Cq.Workplane:
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width = self.width_base + self.battery_dist * (self.n_batteries - 1) + self.battery_diam
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return (
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Cq.Workplane('XY')
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.box(
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length=self.length,
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width=width,
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height=self.height,
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centered=(True, True, False),
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)
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.copyWorkplane(Cq.Workplane('XY', origin=(0, 0, self.thickness)))
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.box(
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length=self.length - self.thickness*2,
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width=width - self.thickness*2,
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height=self.height - self.thickness,
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centered=(True, True, False),
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combine='cut',
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)
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.copyWorkplane(Cq.Workplane('XY', origin=(-self.battery_height/2, 0, self.thickness + self.battery_diam/2)))
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.rarray(
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xSpacing=1,
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ySpacing=self.battery_dist,
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xCount=1,
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yCount=self.n_batteries,
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center=True,
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)
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.cylinder(
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radius=self.battery_diam/2,
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height=self.battery_height,
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direct=(1, 0, 0),
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centered=(True, True, False),
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combine=True,
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)
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)
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LINEAR_ACTUATOR_50 = LinearActuator(
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mass=34.0,
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stroke_length=50,
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# FIXME: Measure
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front_hole_ext=6,
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back_hole_ext=6,
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segment1_length=50,
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segment2_length=50,
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)
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LINEAR_ACTUATOR_30 = LinearActuator(
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mass=34.0,
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stroke_length=30,
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)
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LINEAR_ACTUATOR_21 = LinearActuator(
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# FIXME: Measure
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mass=0.0,
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stroke_length=21,
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front_hole_ext=4,
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back_hole_ext=4,
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segment1_length=75/2,
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segment2_length=75/2,
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)
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LINEAR_ACTUATOR_10 = LinearActuator(
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# FIXME: Measure
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mass=0.0,
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stroke_length=10,
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front_hole_ext=4.5/2,
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back_hole_ext=4.5/2,
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segment1_length=30.0,
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segment2_length=30.0,
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)
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LINEAR_ACTUATOR_HEX_NUT = HexNut(
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mass=0.8,
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diam_thread=4,
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pitch=0.7,
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thickness=4.16,
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width=6.79,
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)
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LINEAR_ACTUATOR_BOLT = FlatHeadBolt(
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mass=1.7,
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diam_head=6.68,
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height_head=2.98,
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diam_thread=4.0,
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height_thread=15.83,
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)
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LINEAR_ACTUATOR_BRACKET = MountingBracket()
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BATTERY_BOX = BatteryBox18650()
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@dataclass
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class Flexor:
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"""
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Actuator assembly which flexes, similar to biceps
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"""
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motion_span: float
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actuator: LinearActuator = LINEAR_ACTUATOR_50
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nut: HexNut = LINEAR_ACTUATOR_HEX_NUT
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bolt: FlatHeadBolt = LINEAR_ACTUATOR_BOLT
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bracket: MountingBracket = LINEAR_ACTUATOR_BRACKET
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# FIXME: Add a compression spring so the serviceable distances are not as fixed
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mount_loc_r: float = float('nan')
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mount_loc_angle: float = float('nan')
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def __post_init__(self):
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d_open = self.actuator.conn_length + self.actuator.stroke_length
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d_closed = self.actuator.conn_length
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theta = math.radians(self.motion_span)
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def target(args):
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r, phi = args
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e1 = d_open * d_open - 2 * r * r * (1 - math.cos(theta + phi))
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e2 = d_closed * d_closed - 2 * r * r * (1 - math.cos(phi))
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return [e1, e2]
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self.mount_loc_r, phi = SO.fsolve(target, [self.actuator.conn_length, theta])
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self.mount_loc_angle = math.degrees(theta + phi)
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@property
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def mount_height(self):
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return self.bracket.hole_to_side_ext
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@property
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def min_serviceable_distance(self):
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return self.bracket.hole_to_side_ext * 2 + self.actuator.conn_length
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@property
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def max_serviceable_distance(self):
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return self.min_serviceable_distance + self.actuator.stroke_length
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def target_length_at_angle(
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self,
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angle: float = 0.0
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) -> float:
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# law of cosines
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r = self.mount_loc_r
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th = math.radians(self.mount_loc_angle - angle)
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d2 = 2 * r * r * (1 - math.cos(th))
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return math.sqrt(d2)
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def add_to(
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self,
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a: Cq.Assembly,
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target_length: float,
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tag_prefix: Optional[str] = None,
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tag_hole_front: Optional[str] = None,
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tag_hole_back: Optional[str] = None,
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tag_dir: Optional[str] = None):
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"""
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Adds the necessary mechanical components to this assembly. Does not
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invoke `a.solve()`.
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"""
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pos = (target_length - self.actuator.conn_length) / self.actuator.stroke_length
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if tag_prefix:
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tag_prefix = tag_prefix + "_"
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name_actuator = f"{tag_prefix}actuator"
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name_bracket_front = f"{tag_prefix}bracket_front"
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name_bracket_back = f"{tag_prefix}bracket_back"
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name_bolt_front = f"{tag_prefix}front_bolt"
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name_bolt_back = f"{tag_prefix}back_bolt"
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name_nut_front = f"{tag_prefix}front_nut"
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name_nut_back = f"{tag_prefix}back_nut"
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(
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a
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.add(self.actuator.assembly(pos=pos), name=name_actuator)
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.add(self.bracket.assembly(), name=name_bracket_front)
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.add(self.bolt.assembly(), name=name_bolt_front)
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.add(self.nut.assembly(), name=name_nut_front)
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.constrain(f"{name_actuator}/front?conn", f"{name_bracket_front}?conn_mid",
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"Plane", param=0)
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.constrain(f"{name_bolt_front}?root", f"{name_bracket_front}?conn_top",
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"Plane", param=0)
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.constrain(f"{name_nut_front}?bot", f"{name_bracket_front}?conn_bot",
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"Plane")
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.add(self.bracket.assembly(), name=name_bracket_back)
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.add(self.bolt.assembly(), name=name_bolt_back)
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.add(self.nut.assembly(), name=name_nut_back)
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.constrain(f"{name_actuator}/back?conn", f"{name_bracket_back}?conn_mid",
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"Plane", param=0)
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.constrain(f"{name_bolt_back}?root", f"{name_bracket_back}?conn_top",
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"Plane", param=0)
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.constrain(f"{name_nut_back}?bot", f"{name_bracket_back}?conn_bot",
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"Plane")
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)
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if tag_hole_front:
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a.constrain(tag_hole_front, f"{name_bracket_front}?conn_side", "Plane")
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if tag_hole_back:
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a.constrain(tag_hole_back, f"{name_bracket_back}?conn_side", "Plane")
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if tag_dir:
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a.constrain(tag_dir, f"{name_bracket_front}?conn_mid", "Axis", param=0)
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