diff --git a/notebooks/Object_following-avoid/servoserial.py b/notebooks/Object_following-avoid/servoserial.py
new file mode 100644
index 00000000..646d2e01
--- /dev/null
+++ b/notebooks/Object_following-avoid/servoserial.py
@@ -0,0 +1,86 @@
+#-*- coding:UTF-8 -*-
+import RPi.GPIO as GPIO
+import time
+import string
+import serial
+
+#Set the GPIO port to BCM encoding mode.
+GPIO.setmode(GPIO.BCM)
+
+class ServoSerial:
+    def __init__(self):
+        self.ser = serial.Serial("/dev/ttyTHS1", 115200, timeout = 0.001)
+        print ("serial Open!")
+    
+    def __del__(self):
+        self.ser.close()
+        print ("serial Close!")
+
+    def Servo_serial_control(self, index, angle):
+        pack1 = 0xff
+        pack2 = 0xff
+        id = index
+        len = 0x07
+        cmd = 0x03
+        addr = 0x2A
+        #Keep the servo pulse of the servo within a safe range
+        if index == 1:
+            if angle<600:
+                angle=600
+            elif angle>3600:
+                angle = 3600
+        elif index == 2:
+            if angle<1300:
+                angle=1300
+            elif angle>4095:
+                angle=4095
+
+        pos_H = (angle >> 8) & 0x00ff
+        pos_L = angle & 0x00ff
+        
+        time_H = 0x00   # time = 500ms Decomposed into two
+        time_L = 0x0A
+        checknum = (~(id + len + cmd + addr + pos_H + pos_L + time_H + time_L)) & 0xff
+        print(checknum)
+        data = [pack1, pack2, id, len, cmd, addr, pos_H, pos_L, time_H, time_L, checknum]
+        print(bytes(data))
+        self.ser.write(bytes(data))
+
+    def Servo_serial_double_control(self, index_1, angle_1, index_2, angle_2):
+        pack1 = 0xff
+        pack2 = 0xff
+        id = 0xFE
+        id_1 = index_1
+        id_2 = index_2
+        len = 0x0E
+        cmd = 0x83
+        addr1 = 0x2A
+        addr2 = 0x04
+        #Keep the servo pulse of the servo within a safe range
+        if angle_1<600:
+            angle_1=600
+        elif angle_1>3600:
+            angle_1 = 3600
+
+        if angle_2<1300:
+            angle_2=1300
+        elif angle_2>4095:
+            angle_2=4095
+
+        pos1_H = (angle_1 >> 8) & 0x00ff
+        pos1_L = angle_1 & 0x00ff
+
+        pos2_H = (angle_2 >> 8) & 0x00ff
+        pos2_L = angle_2 & 0x00ff
+        
+        time1_H = 0x00   # time = 10ms Decomposed into two
+        time1_L = 0x0A
+
+        time2_H = 0x00   # time = 10ms Decomposed into two
+        time2_L = 0x0A
+
+        checknum = (~(id + len + cmd + addr1 + addr2 + id_1 + pos1_H + pos1_L + time1_H + time1_L + id_2 + pos2_H + pos2_L + time2_H + time2_L)) & 0xff
+        print(checknum)
+        data = [pack1, pack2, id, len, cmd, addr1, addr2, id_1, pos1_H, pos1_L, time1_H, time1_L, id_2, pos2_H, pos2_L, time2_H, time2_L, checknum]
+        print(bytes(data))
+        self.ser.write(bytes(data))
\ No newline at end of file
diff --git a/notebooks/Object_following-optimized/PID.py b/notebooks/Object_following-optimized/PID.py
new file mode 100644
index 00000000..147759ab
--- /dev/null
+++ b/notebooks/Object_following-optimized/PID.py
@@ -0,0 +1,67 @@
+#  PID control first-order inertial system test program
+#*****************************************************************#
+#                      Incremental PID system                     #
+#*****************************************************************#
+class IncrementalPID:
+    def __init__(self, P, I, D):
+        self.Kp = P
+        self.Ki = I
+        self.Kd = D
+ 
+        self.PIDOutput = 0.0             #PID controller output
+        self.SystemOutput = 0.0          #System output value
+        self.LastSystemOutput = 0.0      #Last system output value
+ 
+        self.Error = 0.0                 #The deviation of the output value from the input value
+        self.LastError = 0.0
+        self.LastLastError = 0.0
+ 
+    #Set the PID controller parameters
+    def SetStepSignal(self,StepSignal):
+        self.Error = StepSignal - self.SystemOutput
+        IncrementValue = self.Kp * (self.Error - self.LastError) +\
+        self.Ki * self.Error +\
+        self.Kd * (self.Error - 2 * self.LastError + self.LastLastError)
+
+        self.PIDOutput += IncrementValue
+        self.LastLastError = self.LastError
+        self.LastError = self.Error
+
+    #Set the first-order inertial link system, where InertiaTime is the inertia time constant
+    def SetInertiaTime(self,InertiaTime,SampleTime):
+        self.SystemOutput = (InertiaTime * self.LastSystemOutput + \
+            SampleTime * self.PIDOutput) / (SampleTime + InertiaTime)
+
+        self.LastSystemOutput = self.SystemOutput
+ 
+ 
+# *****************************************************************#
+#                      Positional PID system                       #
+# *****************************************************************#
+class PositionalPID:
+    def __init__(self, P, I, D):
+        self.Kp = P
+        self.Ki = I
+        self.Kd = D
+ 
+        self.SystemOutput = 0.0
+        self.ResultValueBack = 0.0
+        self.PidOutput = 0.0
+        self.PIDErrADD = 0.0
+        self.ErrBack = 0.0
+    
+    #Set the PID controller parameters
+    def SetStepSignal(self,StepSignal):
+        Err = StepSignal - self.SystemOutput
+        KpWork = self.Kp * Err
+        KiWork = self.Ki * self.PIDErrADD
+        KdWork = self.Kd * (Err - self.ErrBack)
+        self.PidOutput = KpWork + KiWork + KdWork
+        self.PIDErrADD += Err
+        self.ErrBack = Err
+
+    #Set the first-order inertial link system, where InertiaTime is the inertia time constant
+    def SetInertiaTime(self, InertiaTime,SampleTime):
+       self.SystemOutput = (InertiaTime * self.ResultValueBack + \
+           SampleTime * self.PidOutput) / (SampleTime + InertiaTime)
+       self.ResultValueBack = self.SystemOutput
\ No newline at end of file