我正在使用python脚本来控制驱动翻译台的步进电机
舞台有两个限位开关，一个靠近电机(位于底部(，另一个远离电机(顶部(
我参考电机附近限位开关处的电机，该限位开关将该位置控制器的内部步数设置为0。
但是，我希望默认的0位置始终位于顶部。因此，根据我选择的参考点，在将其发送到控制器之前，我必须重新计算步数。
像这样：
if self.__reference_point == 'near':
steps = steps - 50000
当我调用函数move_absolute(0)时，电机总是移动到顶部。
但是，如果我用从MATLAB调用这个脚本
lt = py.lt_control.LT('COM4');
lt.do_referencing();
lt.move_absolute(0);
舞台移回底部。因此，步数的转换似乎以某种方式失败了
为什么
我安装了python 3.7.8 x64
步进控制器是nanotec SMCI33-1，如果有用的话。
这里是大部分python文件，我删除了不相关的函数。
import serial
import time
from decimal import Decimal
import signal
class MotorNotReferencedError(Exception):
def __init__(self):
super().__init__('Motor not referenced! Please call do_referencing()!')
class LT(object):
def __init__(self, portname, reference='near', com_timeout=1):
"""
Create a new motor control object.
:param portname: The Port for the serial connection (e.g. 'COM4' for Windows, '/dev/ttyS1' for Linux)
:param reference: Which limit switch will be used for referencing the motor, far means away from motor, near means near, coordinates are positive away from reference
:param com_timeout: Timeout in sek for serial port
"""
signal.signal(signal.SIGINT, self.sig_handler)
signal.signal(signal.SIGTERM, self.sig_handler)
self.__serial_port = serial.Serial(portname, 115200, timeout=com_timeout)
self.__debug = False
self.__substeps = 8 #does not do anything right now, for future
self.__reference_point = reference
self.__reference_changed = False
self.__status = 1
self.__positioning_error = 0
self.setup_defaults()
if not self.is_referenced():
print('Referencing is required!')
def __delete__(self, instance):
if self.__serial_port:
self.__serial_port.close()
def __del__(self):
if self.__serial_port:
self.__serial_port.close()
def sig_handler(self, sig, fr):
self.stop()
print('Keyboard Interrupt: Motor stopped!')
def close(self):
self.__serial_port.close()
def query(self, message):
"""
Send a message to the controller with newline char and reads response.
:param message: The message to send, should be in proper syntax
:returns: The response without newline
:rtype: String
"""
msg = message + 'r'
if self.__debug: print(message)
self.__serial_port.write(msg.encode())
ans = self.__serial_port.read_until(b'r').decode('utf-8')
if len(ans) == 0:
raise TimeoutError
else:
if self.__debug: print(ans.strip())
return ans.strip()
def is_referenced(self):
"""
Check whether the motor is referenced.
This is necessary after every loss of power to the controller
:returns: True if motor is referenced
:rtype: Boolean
"""
ans = self.query('#1:is_referenced')
if ans[-1] == '1' and not self.__reference_changed:
return True
else:
return False
def setup_defaults(self):
self.command('#1g8') # microstepping, 8 microsteps per step
def command(self, message):
"""
Send commands to controller. Check if write was successful.
This is simply a query wrapper that does a validity check on the commandsand checks the response of the controller.
:param message: Query like string, following the proper syntax
:returns: True if operation was successful, else False
:rtype: Boolean
"""
ans = self.query(message)
if ans[-1] == '?':
return False
else:
return True
def fetch_status(self):
"""
Fetch status from controller, extract integer value, save positioning error and state to internal variable for later use.
:returns: The status value
:rtype: int
.. seealso:: is_control_ready(), has_position_error()
"""
#extract int value and mask only useful 4 bits
tmp = self.query('#1$')[-3:]
tmp = int(tmp)
self.__status = tmp & 0xF
#self.__status = int(self.query('#1$')[-3:]) & 0xF
self.__positioning_error = (self.__status & 0b0100) >> 2
return self.__status
def is_control_ready(self):
"""
Check if the control is ready for movement
:returns: True if control is ready
:rtype: Boolean
"""
ans = self.fetch_status()
if ans & 1:
return True
else:
return False
def has_positioning_error(self):
"""
Check control if a positioning error has occured since last clear_positioning_error()
:returns: True if a positioning error has occured
:rtype: Boolean
.. seealso:: clear_position_error
"""
self.fetch_status()
if self.__positioning_error:
return True
else:
return False
def clear_positioning_error(self, reset_position=False):
"""
Clear the positioning error to reenable movement.
:param reset_postiton: False (default): Absolute position does not change, True: Set current absolute position to 0
"""
self.__positioning_error = 0
if reset_position:
self.query('#1D0')#1C')
ans = ans[2:] # extract position
self.query('#1D' + ans) # clear error and set position
def steps_to_mm(self, steps):
"""
Converts the number of steps to distance in millimeters
:param steps: The number of steps
:returns: The distance in millimeters
"""
steps_per_turn = self.__substeps * 200
return (1.25/steps_per_turn) * steps
def mm_to_steps(self, mm):
"""
Converts the distance in millimeters to number of steps
:param mm: The distance in millimeters
:returns: The number of steps
"""
steps_per_turn = self.__substeps * 200
return int(round(Decimal((steps_per_turn/1.25) * mm)))
def wait_movement(self):
"""
Wait for movement ot finish.
"""
while not self.is_control_ready():
time.sleep(0.1)
if self.has_positioning_error():
# in endschalter gelaufen
# reset position
self.clear_positioning_error()
print('Movement ended prematurely, limit switch engaged!')
def stop(self):
"""
Immediately stops the motor
"""
self.command('#1S')
def set_reference_point(self, reference):
"""
Redefine the reference point.
:param reference: Which limit switch will be used for referencing the motor, 'far' means away from motor, 'near' means near, coordinates are positive away from reference
"""
self.__reference_point = reference
self.__reference_changed = True
print('Please reference motor again!')
def do_referencing(self):
"""
Reference the motor to the limit switch defined by the reference
point.
"""
self.command('#1p4')
self.command('#1l5154') # endschalterverhalten auf r�ckw�rts vom schalter runterfahren
if self.__reference_point == 'near':
self.command('#1d1')
else:
self.command('#1d0')
self.command('#1o4000')
self.command('#1A')
self.wait_movement()
self.__reference_changed = False
def move_relative(self, steps, speed=4000):
"""Move the Stage relative to its current position.
:param steps: number of steps to travel, max 50000
steps < 0: Movement towards reference
steps > 0: Movemento away from reference
:param speed: Speed in steps/s (max 16000)
"""
if abs(steps) > 50000:
print("Relative Movement: Too many steps!")
return
if self.__reference_point == 'far':
self.command('#1d1')
else:
self.command('#1d0')
self.command('#1o' + str(speed))
self.command('#1s' + str(steps))
self.command('#1A')
self.wait_movement()
def move_absolute(self, steps, speed=4000):
"""Move the Stage to absolute position, 0 is opposite of motor.
:param steps: Absolute position between 0 and 50000
:param speed: Speed in steps/s
"""
if not self.is_referenced():
raise MotorNotReferencedError
if abs(steps) > 50000:
print('Absolute Movement: Too many steps!')
return
print("" + str(steps))
if not self.__reference_point == 'far':
steps = steps - 50000
print("" + str(steps))
self.command('#1p2')
self.command('#1o' + str(speed))
self.command('#1s' + str(steps))
self.command('#1A')
self.wait_movement()
def move_relative_mm(self, distance_mm, speed=3):
"""Move the Stage relative to its current position.
:param distance_mm: travel distance in millimeters
< 0: Movement away from motor
> 0: Movement towards motor
:param speed: Speed in mm/s
"""
steps = self.mm_to_steps(distance_mm)
speed = self.mm_to_steps(speed)
self.move_relative(steps, speed)
def move_absolute_mm(self, position_mm, speed=3):
"""Move the Stage to absolute position, 0 ist limit switch opposite of motor.
:param position_mm: Absolute position between 0 and 39
:param speed: Speed in mm/s
"""
if not self.is_referenced():
raise MotorNotReferencedError
steps = self.mm_to_steps(position_mm)
speed = self.mm_to_steps(speed)
self.move_absolute(steps, speed)
def get_position(self):
"""Return absolute position in steps.
:returns: absolute position in steps
"""
real_pos = int(self.query('#1C')[2:])
if self.__reference_point == 'far':
disp_pos = real_pos
else:
disp_pos = real_pos + 50000
return disp_pos
因此，当从MATLAB调用时，str(steps)似乎返回浮点表示'0.0'，其中它需要是整数'0'才能工作。
将其更改为str(int(steps))解决了问题
但奇怪的是，普通的python解释器对此没有问题。
正如Cris Luengo所指出的：当从MATLAB调用lt.move_absolute(0)时，0是一个浮点数。这就是从python命令行调用相同表达式的区别。