Vehicles Avoidance and Identify System

1
?????????????????????????? (Vehicles Avoidance
and Identify System)

• TRS

2
??????

• ??????????
• ?????????????? (Sensors)
• ??????????????????? (Avoid Obstacle System)
• ????????????? (Identify System)
• ????

3
??????????

• ?????????? ??????????????????????????????????????
  ???????????????? ?????????????????????????????
  ????????????????????????? ???? Sonars ??? Laser
  Scanner ??????????????????????????????????????????
  ??? ??????????????? ??????????????????????????????
  ???? ?????????????????????????????????????????????
  ??????????????????? ?????????????????
  ?????????????????? ?????????????
  ?????????????????????? ????????????????????????
  (Fuzzy Control) ??????????????????????????????
  (Basic Behaviors) ????????????????????????????????
  ?????????????? ??????????????????????????????????
  ??????????

4
?????????????? (Sensors)

• ?????????????????????????????????
• ?????????????????????? (Velocity Sensors)
• ???????????????????? (Heading Sensors)
• ?????????????????? (Distance Sensors)
• ????????????????????? (Position Sensors)

5
?????????????????????? (Velocity Sensors)

• ????????????????????????????????????? (Inertia
  Navigation Systems) ???????? gyroscope
  ?????????????????? (acceleration)
  ????????????????? (x, y, z) ????????? integrate
  ??????????????????? ???????????????????????????
  (???? DMU-6x)
• ??????????????????????????? Optical Encoders
  ?????????????????????????????????????????????

6
???????????????????? (Heading Sensors)

• Gyroscopes provides angle relative to robot, but
  are not good when the robot is turning very
  slowly.
• Compasses
• Magnetic Compasses
• Halls effect Compasses
• Fluxgate Compasses (i.e. KVH C100)

7
?????????????????? (Distance Sensors)

• Ultrasonic or Sonar Sensors measures the time
  elapsed between the transmission of a signal and
  the receiving of an echo of transmitted signal
  (time of flight) to determine the distance to an
  obstacle.
• Laser Sensors An optical measurement sensor
  system with a useful range of 0.3 to 50 m. for
  most diffuse reflective surfaces. It operates by
  emitting a collimated laser beam that is
  reflected from the target surface and collected
  by the sensor. The sensor is suitable for a wide
  variety of distance measurement applications that
  demand accuracy and fast response times.

8
Laser Sensors
Comparison of commercially available scanning
laser rangefinders
9
????????????????????? (Position Sensors)

• Dead Reckoning a simple procedure for
  determining the robots position. The most
  simplistic implementation of dead reckoning is
  called odometry which involves optical encoders
  directly coupled to the motor armatures or wheel
  axles.
• GPS a satellite navigation system. The GPS
  receiver will be considered as a global
  navigation device for mobile robots.

10
??????????????????? (Avoid Obstacle System)

• ??????????????????? ?? 2 ????? ????????????
  ?????????? ??????????????????????????Virtual
  Force Field (VFF) ??????????? ????????????????????
  ??? (Fuzzy-based Obstacle Avoidance)

11
Virtual Force Field
12
Fuzzy-based Obstacle Avoidance

• Feature extraction Read sonar and laser data
• Construct three membership functions for each
  Input
• Construct five MFs for output
• Construct nine rules for avoiding
• Defuzzification

13
Feature Extraction
Each fuzzy input is given by (e.g. sonar sensor)
Construct three membership functions for each
input
14
Input MFs
ZR MD
LG
15
MFs for Output 1 (w)
NB N Z P PB
16
MFs for Output 2 (v)
NB,N, P, PB
17
Rules for Output 1 (w)
18
Rules for Output 2 (v)
19
If-Then Rules
20
FIS 1
21
FIS 2
22
The output surface of a fuzzy system for angular
velocity and linear velocity
linear velocity
angular velocity
23
??????????????????
24
Avoid-Obstacle Behavior
--- Agent
Avoid-obstacle (Fuzzy)
S
Base Server
Avoid-obstacle (VFF)
S
25
????????????? (Identify System)

• ????????????????? ???????????????????????
  ??????????????????? ??????????????????????????????
  ????????????????????????????????? ???????????????
  ??????????????????????????????????????????????????
  ???? ?????????????????????????????

26
Learning Fuzzy Rules Technique

• Generate a Set of Fuzzy Rules

27
Learning Fuzzy Rules (Cont.)

• Reinforcement Learning Gain

28
Learning Fuzzy Rules (Cont.)

• Integrate a Set of Fuzzy Rules

29
????????????????????

• ??????????
• Sonar ??? Laser
• ?????????????? fuzzy inputs
• Obstacle force from all obstacle distances
• Closest obstacle distance
• Closest obstacle direction

30
Learning Fuzzy Rules

• Fuzzify the sensory readings
• Obstacle force direction (q )
• Closest obstacle distance (d )
• Closest obstacle direction (q )
• Fuzzify the motor action
• Linear velocity (v)
• Angular velocity (w )
• Learning to built a set of fuzzy rules

force
min
min
31
Learning Fuzzy Rules
Fuzzify
Max(.)
Max(.)
Obst. Force (q )
Linear Velocity
force
Xin-1
Yin
Closest obst. (d )
min
Angular Velocity
Closest obst. (q )
min
Inputs
Outputs
Rules
Example of Fuzzy Rules
32
Example of fuzzy rules for avoid-obstacle
behavior
Fuzzy Control
33
Fuzzy Control
Adaptive fuzzy rules
Defuzzify
Fuzzify
Max(.)
Obst. Force (q )
Linear Velocity
Xin
force
Yin
Closest obst. (d )
min
Angular Velocity
Closest obst. (q )
min
Inputs
Outputs
Rules
34
Fuzzy Control
Adaptive fuzzy rules
Defuzzify
Fuzzify
Max(.)
Obst. Force (q )
Linear Velocity
Xin
force
Yin
Closest obst. (d )
min
Angular Velocity
Closest obst. (q )
min
Inputs
Outputs
Rules
35
????????????????
Ex1 ??????????????????????????????????????Ex2
?????????????????????????????????
36
????

• ???????????????????????? (Data Client-Server)
  ??????????????? ?????????????????????????
  ?????????????????????????????
• ?????????????????????????? ???????????????????????
  ?? (Move to Point Behavior), ?????????????????
  (Avoid Obstacle Behavior) ???????????????????????
  ?????????? (Wander Behavior)
• ??????????????????????????????????????????????
  ????????????? Subsumption ??? Motor Schemas
• ???????????????????????????????????
  ?????????????????????????????
• ???????????????????? C ?????????????????????
  Linux
• ?????????????????????????????????

37
?????????????

• S. Thongchai,"Sensory Motor Coordination Based
  Fuzzy Control for Mobile Robots Learning ", TRS
  Conference on Robotics and Industrial Technology
  2004,(CRIT 2004), Rose Garden Aprime Resort,
  Sampran, Nakorn Patho, Thailand, 26-27 March,
  2004.
• S. Thongchai, "Behavior-Based Learning Fuzzy
  Rules for Mobile Robots", American Control
  Conference, Anchorage, Alaska, 2002.
• S. Thongchai and K. Kawamura,"Application of
  Fuzzy Control to a Sonar-Based Obstacle Avoidance
  Mobile Robot", Proceedings of the IEEE
  International Conference on Control Applications
  , Anchorage, Alaska, USA, September 25-27, 2000.