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  • PID object has no attribute 'set',我在寻迹小车实例添加一个函数,为什么会这样?



    • pid.py

      from pyb import millis
      from math import pi, isnan
      
      class PID:
          _kp = _ki = _kd = _integrator = _imax = 0
          _last_error = _last_derivative = _last_t = 0
          _RC = 1/(2 * pi * 20)
          def __init__(self, p=0, i=0, d=0, imax=0):
              self._kp = float(p)
              self._ki = float(i)
              self._kd = float(d)
              self._imax = abs(imax)
              self._last_derivative = float('nan')
          def set(self)
              pass
          def get_pid(self, error, scaler):
              tnow = millis()
              dt = tnow - self._last_t
              output = 0
              if self._last_t == 0 or dt > 1000:
                  dt = 0
                  self.reset_I()
              self._last_t = tnow
              delta_time = float(dt) / float(1000)
              output += error * self._kp
              if abs(self._kd) > 0 and dt > 0:
                  if isnan(self._last_derivative):
                      derivative = 0
                      self._last_derivative = 0
                  else:
                      derivative = (error - self._last_error) / delta_time
                  derivative = self._last_derivative + \
                                           ((delta_time / (self._RC + delta_time)) * \
                                              (derivative - self._last_derivative))
                  self._last_error = error
                  self._last_derivative = derivative
                  output += self._kd * derivative
              output *= scaler
              if abs(self._ki) > 0 and dt > 0:
                  self._integrator += (error * self._ki) * scaler * delta_time
                  if self._integrator < -self._imax: self._integrator = -self._imax
                  elif self._integrator > self._imax: self._integrator = self._imax
                  output += self._integrator
              return output
          def reset_I(self):
              self._integrator = 0
              self._last_derivative = float('nan')
      

      car.py

      from pyb import Pin, Timer
      inverse_left=False  #change it to True to inverse left wheel
      inverse_right=False #change it to True to inverse right wheel
      
      ain1 =  Pin('P0', Pin.OUT_PP)
      ain2 =  Pin('P1', Pin.OUT_PP)
      bin1 =  Pin('P2', Pin.OUT_PP)
      bin2 =  Pin('P3', Pin.OUT_PP)
      ain1.low()
      ain2.low()
      bin1.low()
      bin2.low()
      
      pwma = Pin('P7')
      pwmb = Pin('P8')
      tim = Timer(4, freq=1000)
      ch1 = tim.channel(1, Timer.PWM, pin=pwma)
      ch2 = tim.channel(2, Timer.PWM, pin=pwmb)
      ch1.pulse_width_percent(0)
      ch2.pulse_width_percent(0)
      
      def run(left_speed, right_speed):
          if inverse_left==True:
              left_speed=(-left_speed)
          if inverse_right==True:
              right_speed=(-right_speed)
      
          if left_speed < 0:
              ain1.low()
              ain2.high()
          else:
              ain1.high()
              ain2.low()
          ch1.pulse_width_percent(abs(left_speed))
      
          if right_speed < 0:
              bin1.low()
              bin2.high()
          else:
              bin1.high()
              bin2.low()
          ch2.pulse_width_percent(abs(right_speed))
      

      main.py

      THRESHOLD = (5, 70, -23, 15, -57, 0)
      import sensor, image, time
      from pyb import LED
      import car
      from pid import PID
      rho_pid = PID(p=0.4, i=0)
      theta_pid = PID(p=0.001, i=0)
      LED(1).on()
      LED(2).on()
      LED(3).on()
      sensor.reset()
      sensor.set_vflip(True)
      sensor.set_hmirror(True)
      sensor.set_pixformat(sensor.RGB565)
      sensor.set_framesize(sensor.QQQVGA)
      sensor.skip_frames(time = 2000)
      clock = time.clock()
      rho_pid.set()
      while(True):
          clock.tick()
          img = sensor.snapshot().binary([THRESHOLD])
          line = img.get_regression([(100,100,0,0,0,0)], robust = True)
          if (line):
              rho_err = abs(line.rho())-img.width()/2
              if line.theta()>90:
                  theta_err = line.theta()-180
              else:
                  theta_err = line.theta()
              img.draw_line(line.line(), color = 127)
              print(rho_err,line.magnitude(),rho_err)
              if line.magnitude()>8:
                  rho_output = rho_pid.get_pid(rho_err,1)
                  theta_output = theta_pid.get_pid(theta_err,1)
                  output = rho_output+theta_output
                  car.run(50+output, 50-output)
              else:
                  car.run(0,0)
          else:
              car.run(50,-50)
              pass
      


    • 你有没有把pid.py放到OpenMV里?



    • @kidswong999 我添加实例,然后自己写一个函数用来类外设置p,i,d值,一运行程序就出问题