将步进电机移动到精确位置

Question

我的设置：一个 Arduino 从串行（步数）中读取数字，然后它将步进电机移动许多步。它使用 a4988 驱动器，12 伏电源，1.5 安培 Nema 17。一切都很好，我的问题在于 Python 方面。

在 Python 中，我尝试过以多种方式创建函数。 我使用 tkinter 来获取屏幕上的鼠标位置，它在 x 轴上移动，旋转步进器。步进器有一个手电筒，可以照亮我用鼠标指向的任何东西。

假设步进器下方有一个摄像头，如果我将鼠标移到一个物体上，它会移到那里，无论哪种方式都在 5 步的容差范围内。 +5, -5 我尝试创建的函数应该是这样工作的。

while True:
#I change direction by writing 400, clockwise, or 401, anti clockwise to serial.
    step(10)#move only 10 steps
    step(10)#it should do nothing as it has already moved 10 steps.
    step(15)#it should move 5 steps as it has moved 10 already
    step(5)#change direction and move back 10 steps
I am somewhat decent at python(or so I think)
here is my most promising code so far:

#I have direction changes done by writing a 400 for clockwise or 401 for anti clockwise to serial.
import tkinter as tk
import serial
ser = serial.Serial("COM8", 9600)
root = tk.Tk()
wi = root.winfo_screenwidth() / 2
width = root.winfo_screenwidth()
hi = root.winfo_screenheight() / 2
height = root.winfo_screenheight()
sere = '\r\n'
sender = sere.encode('utf_8')
pps = height / 200 
# p.p.s pixels per step divide that by the same thing to get correct.
#how many pixels are for 1 step
print(pps)
#number of pixels difference divided by pps to get steps, then round for ease of use
past = 0
print(height, width, wi) # height divided by pps should always = max steps in my case 200
def send(steps):
        global past
        global current
        sere = '\r\n'
        current = steps
        neg = past - 5
        pos = past + 5
        if current != past:
                if current > pos or current < neg:
                        if steps > 1:
                                sender = sere.encode('utf_8')
                                e = str(steps).encode('utf_8')
                                ser.write(e + sender)
        past = steps
while True:
        pos = root.winfo_pointerx() - wi
        steps = round(pos / pps)
        print(pos, steps) # shows cursor position
#direction code is not in here as I have no need for it atm.For one simple reason, IT DOESN'T WORK!

如果可能，请解释答案，我是一个长期的潜伏者，只是为了这个才注册了一个帐户。谢谢大家的帮助。 编辑： 问题是如何制作一个将步进电机移动到一定步数的功能。如果你命令它两次执行 10 步，它只会移动 10 步。 step(10) 步进器移动 10 步，再做一次电机什么也不做，因为它已经是 10 步了。 如果我执行第（15）步，它只会再移动 5 步，因为它是 10 步。 Edit2 说明： 我的意思是功能

def step(steps):
    #logic that makes it work

Answer 1

对于遇到此问题并且人们似乎无能为力的其他人，这是我的新代码来驱动它，

past = 0
sender = sere.encode('utf_8')
dir1 = str(400).encode('utf_8')
dir2 = str(401).encode('utf_8')
def send(steps):
        global past
        global current
        global sender
        global dir1
        global dir2
        global stepstaken
        sere = '\r\n'
        current = steps
        neg = past - 5 # tolerance both are unused atm
        pos = past + 5 # tolerance
        needed = current - past
        print(needed, steps)
        if current != past:
                if needed > 0:
                        serialsteps = str(needed).encode('utf_8')
                        ser.write(dir1 + sender)
                        ser.write(serialsteps + sender)
                if needed < 0:
                        needed = needed * -1
                        serialstepss = str(needed).encode('utf_8')
                        ser.write(dir2 + sender)
                        ser.write(serialstepss + sender)
        past = steps

这是我的鼠标到步进电机的完整代码，

import tkinter as tk
root = tk.Tk()
import serial
import struct
import time
stepstaken = 0
ardunioport = "COM" + str(input("Ardunio Port Number:")) # port number only
ser = serial.Serial(ardunioport, 9600)
wi = root.winfo_screenwidth() / 2
width = root.winfo_screenwidth()
hi = root.winfo_screenheight() / 2
height = root.winfo_screenheight()
sere = '\r\n' #still don't understand why but it does not work without this.
sender = sere.encode('utf_8')
pps = width / 200 #how many pixels are in 1 step
past = 0
sender = sere.encode('utf_8')
dir1 = str(400).encode('utf_8')
dir2 = str(401).encode('utf_8')
def send(steps):
        global past
        global current
        global sender
        global dir1
        global dir2
        global stepstaken
        #need overcome overstepping
        sere = '\r\n'
        current = steps
        neg = past - 5 # tolerance 
        pos = past + 5 # tolerance
        needed = current - past
        print(needed, steps)
        if current != past:
                if needed > 0:
                        serialsteps = str(needed).encode('utf_8')
                        ser.write(dir1 + sender)
                        ser.write(serialsteps + sender)
                if needed < 0:
                        needed = needed * -1
                        serialstepss = str(needed).encode('utf_8')
                        ser.write(dir2 + sender)
                        ser.write(serialstepss + sender)
        past = steps

while True:
        pos = root.winfo_pointerx() - wi
        steps = round(pos / pps)
        #print("Mouse Position " + str(pos) + " Steps Needed" + str(steps)) # shows cursor position
        send(steps)        

对我来说，它适用于 Arduino，Arduino 没有被编程为接受负数。相反，它删除了 - 符号，将负数乘以负数 = 正数。它发送相反方向的代码/号码，然后发送到达那里所需的步骤。大家好运。此代码适用于我，不保证它会适用于您。如果不适用，我很抱歉。