cristhian
bde8582de3
The reader owns the pad on a thread of its own, and nothing outside that file may touch pygame: everything else sees a plain immutable Sample. That is what lets the rest of the node be tested with no hardware, and what keeps SDL's quirks out of the arm logic. Sample.present is the field that matters. A pad that has been unplugged reads as absent rather than as centred, so "the operator let go" and "the pad fell off the desk" stay distinguishable — they call for the same stop, but only one of them is worth logging. Only the display and joystick subsystems are initialised. pygame.init() also opens audio, which on a headless robot fills stderr with ALSA errors for a device this node never uses; the display is needed despite there being no window, because SDL refreshes joystick state during the event pump. Settings are parsed once at startup so a deadzone that would silently make the pad inert stops the node before it joins the dataflow.
100 lines
3.7 KiB
Python
100 lines
3.7 KiB
Python
"""Everything the node reads from the environment, parsed once at startup.
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Parsing happens here rather than where each value is used, so an unusable
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setting stops the node before it joins the dataflow instead of surfacing the
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first time somebody picks up the gamepad.
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"""
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import os
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from dataclasses import dataclass, field
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def env_float(name: str, default: float) -> float:
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"""Read a number, naming the variable if it cannot be read as one."""
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value = os.environ.get(name, "").strip()
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if not value:
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return default
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try:
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return float(value)
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except ValueError:
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raise ValueError(f"{name} must be a number, not {value!r}") from None
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def env_int(name: str, default: int) -> int:
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"""Read a whole number, naming the variable if it cannot be read as one."""
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value = os.environ.get(name, "").strip()
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if not value:
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return default
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try:
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return int(value)
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except ValueError:
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raise ValueError(f"{name} must be a whole number, not {value!r}") from None
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@dataclass
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class DeadmanConfig:
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"""How long a source may go quiet before the arm is told to stop.
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Three layers, outermost last. This node re-sends the current velocity every
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tick; `jog_ttl_s` is how long it will keep doing so without hearing from the
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source; and behind both sits the arm node's own `VELOCITY_COMMAND_TTL_S`,
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which the controller enforces whether or not this process is alive.
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Keep them in that order — ours shorter than the controller's — or the
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backstop fires before the thing it is backing up.
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"""
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jog_ttl_s: float = 0.4
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# How long a gamepad may sit untouched before it gives the arm back, so the
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# browser can take over without anyone having to press anything.
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gamepad_idle_release_s: float = 2.0
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# How often to ask the arm for the things telemetry does not carry: whether
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# the tool is engaged, whether freedrive is on, whether it is ready.
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state_poll_s: float = 0.5
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@classmethod
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def from_env(cls) -> "DeadmanConfig":
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"""Build the timings from the environment."""
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return cls(
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jog_ttl_s=env_float("JOG_TTL_S", 0.4),
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gamepad_idle_release_s=env_float("GAMEPAD_IDLE_RELEASE_S", 2.0),
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state_poll_s=env_float("STATE_POLL_S", 0.5),
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)
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@dataclass
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class Config:
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"""The node's settings."""
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# Full-deflection speeds. A stick is analog, so these are the maximum and
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# anything less moves proportionally slower — which is the whole reason a
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# gamepad beats the console's dial pad.
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speed_mm_s: float
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speed_deg_s: float
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# Stick travel to ignore. A worn stick that does not centre would otherwise
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# drive the arm across the table on its own.
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deadzone: float
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# How much of the curve is cubic: 0 is linear, 1 is fully cubic. Fine
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# positioning happens near centre, and expo is what buys resolution there.
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expo: float
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joystick_index: int
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deadman: DeadmanConfig = field(default_factory=DeadmanConfig)
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@classmethod
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def from_env(cls) -> "Config":
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"""Build the configuration from the environment, refusing anything unusable."""
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deadzone = env_float("DEADZONE", 0.12)
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if not 0.0 <= deadzone < 1.0:
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raise ValueError(f"DEADZONE must be at least 0 and below 1, not {deadzone}")
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expo = env_float("EXPO", 0.4)
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if not 0.0 <= expo <= 1.0:
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raise ValueError(f"EXPO must be between 0 and 1, not {expo}")
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return cls(
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speed_mm_s=env_float("SPEED_MM_S", 60.0),
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speed_deg_s=env_float("SPEED_DEG_S", 30.0),
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deadzone=deadzone,
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expo=expo,
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joystick_index=env_int("JOYSTICK_INDEX", 0),
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deadman=DeadmanConfig.from_env(),
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)
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