import asyncio
from typing import Optional
from bluesky.protocols import Flyable, Movable, Preparable, Stoppable
from pydantic import BaseModel, Field
from ophyd_async.core import (
ConfigSignal,
HintedSignal,
StandardReadable,
WatchableAsyncStatus,
)
from ophyd_async.core.async_status import AsyncStatus
from ophyd_async.core.signal import observe_value
from ophyd_async.core.utils import (
DEFAULT_TIMEOUT,
CalculatableTimeout,
CalculateTimeout,
WatcherUpdate,
)
from ..signal.signal import epics_signal_r, epics_signal_rw, epics_signal_x
class MotorLimitsException(Exception):
pass
class InvalidFlyMotorException(Exception):
pass
DEFAULT_MOTOR_FLY_TIMEOUT = 60
DEFAULT_WATCHER_UPDATE_FREQUENCY = 0.2
class FlyMotorInfo(BaseModel):
"""Minimal set of information required to fly a motor:"""
#: Absolute position of the motor once it finishes accelerating to desired
#: velocity, in motor EGUs
start_position: float = Field(frozen=True)
#: Absolute position of the motor once it begins decelerating from desired
#: velocity, in EGUs
end_position: float = Field(frozen=True)
#: Time taken for the motor to get from start_position to end_position, excluding
#: run-up and run-down, in seconds.
time_for_move: float = Field(frozen=True, gt=0)
#: Maximum time for the complete motor move, including run up and run down.
#: Defaults to `time_for_move` + run up and run down times + 10s.
timeout: CalculatableTimeout = Field(frozen=True, default=CalculateTimeout)
[docs]
class Motor(StandardReadable, Movable, Stoppable, Flyable, Preparable):
"""Device that moves a motor record"""
def __init__(self, prefix: str, name="") -> None:
# Define some signals
with self.add_children_as_readables(ConfigSignal):
self.motor_egu = epics_signal_r(str, prefix + ".EGU")
self.velocity = epics_signal_rw(float, prefix + ".VELO")
with self.add_children_as_readables(HintedSignal):
self.user_readback = epics_signal_r(float, prefix + ".RBV")
self.user_setpoint = epics_signal_rw(float, prefix + ".VAL")
self.max_velocity = epics_signal_r(float, prefix + ".VMAX")
self.acceleration_time = epics_signal_rw(float, prefix + ".ACCL")
self.precision = epics_signal_r(int, prefix + ".PREC")
self.deadband = epics_signal_r(float, prefix + ".RDBD")
self.motor_done_move = epics_signal_r(int, prefix + ".DMOV")
self.low_limit_travel = epics_signal_rw(float, prefix + ".LLM")
self.high_limit_travel = epics_signal_rw(float, prefix + ".HLM")
self.motor_stop = epics_signal_x(prefix + ".STOP")
# Whether set() should complete successfully or not
self._set_success = True
# end_position of a fly move, with run_up_distance added on.
self._fly_completed_position: Optional[float] = None
# Set on kickoff(), complete when motor reaches self._fly_completed_position
self._fly_status: Optional[WatchableAsyncStatus] = None
# Set during prepare
self._fly_timeout: Optional[CalculatableTimeout] = CalculateTimeout
super().__init__(name=name)
[docs]
def set_name(self, name: str):
super().set_name(name)
# Readback should be named the same as its parent in read()
self.user_readback.set_name(name)
[docs]
@AsyncStatus.wrap
async def prepare(self, value: FlyMotorInfo):
"""Calculate required velocity and run-up distance, then if motor limits aren't
breached, move to start position minus run-up distance"""
self._fly_timeout = value.timeout
# Velocity, at which motor travels from start_position to end_position, in motor
# egu/s.
fly_velocity = await self._prepare_velocity(
value.start_position,
value.end_position,
value.time_for_move,
)
# start_position with run_up_distance added on.
fly_prepared_position = await self._prepare_motor_path(
abs(fly_velocity), value.start_position, value.end_position
)
await self.set(fly_prepared_position)
await self.velocity.set(fly_velocity)
[docs]
@AsyncStatus.wrap
async def kickoff(self):
"""Begin moving motor from prepared position to final position."""
assert (
self._fly_completed_position
), "Motor must be prepared before attempting to kickoff"
self._fly_status = self.set(
self._fly_completed_position, timeout=self._fly_timeout
)
[docs]
def complete(self) -> WatchableAsyncStatus:
"""Mark as complete once motor reaches completed position."""
assert self._fly_status, "kickoff not called"
return self._fly_status
[docs]
@WatchableAsyncStatus.wrap
async def set(
self, new_position: float, timeout: CalculatableTimeout = CalculateTimeout
):
self._set_success = True
(
old_position,
units,
precision,
velocity,
acceleration_time,
) = await asyncio.gather(
self.user_setpoint.get_value(),
self.motor_egu.get_value(),
self.precision.get_value(),
self.velocity.get_value(),
self.acceleration_time.get_value(),
)
if timeout is CalculateTimeout:
assert velocity > 0, "Motor has zero velocity"
timeout = (
abs(new_position - old_position) / velocity
+ 2 * acceleration_time
+ DEFAULT_TIMEOUT
)
move_status = self.user_setpoint.set(new_position, wait=True, timeout=timeout)
async for current_position in observe_value(
self.user_readback, done_status=move_status
):
yield WatcherUpdate(
current=current_position,
initial=old_position,
target=new_position,
name=self.name,
unit=units,
precision=precision,
)
if not self._set_success:
raise RuntimeError("Motor was stopped")
[docs]
async def stop(self, success=False):
self._set_success = success
# Put with completion will never complete as we are waiting for completion on
# the move above, so need to pass wait=False
await self.motor_stop.trigger(wait=False)
async def _prepare_velocity(
self, start_position: float, end_position: float, time_for_move: float
) -> float:
fly_velocity = (end_position - start_position) / time_for_move
max_speed, egu = await asyncio.gather(
self.max_velocity.get_value(), self.motor_egu.get_value()
)
if abs(fly_velocity) > max_speed:
raise MotorLimitsException(
f"Motor speed of {abs(fly_velocity)} {egu}/s was requested for a motor "
f" with max speed of {max_speed} {egu}/s"
)
# move to prepare position at maximum velocity
await self.velocity.set(abs(max_speed))
return fly_velocity
async def _prepare_motor_path(
self, fly_velocity: float, start_position: float, end_position: float
) -> float:
# Distance required for motor to accelerate from stationary to fly_velocity, and
# distance required for motor to decelerate from fly_velocity to stationary
run_up_distance = (
(await self.acceleration_time.get_value()) * fly_velocity * 0.5
)
self._fly_completed_position = end_position + run_up_distance
# Prepared position not used after prepare, so no need to store in self
fly_prepared_position = start_position - run_up_distance
motor_lower_limit, motor_upper_limit, egu = await asyncio.gather(
self.low_limit_travel.get_value(),
self.high_limit_travel.get_value(),
self.motor_egu.get_value(),
)
if (
not motor_upper_limit >= fly_prepared_position >= motor_lower_limit
or not motor_upper_limit
>= self._fly_completed_position
>= motor_lower_limit
):
raise MotorLimitsException(
f"Motor trajectory for requested fly is from "
f"{fly_prepared_position}{egu} to "
f"{self._fly_completed_position}{egu} but motor limits are "
f"{motor_lower_limit}{egu} <= x <= {motor_upper_limit}{egu} "
)
return fly_prepared_position
