Building Robot In A Simple Way

1
Building Robot In A Simple Way

• Case study
• Robot Colony
• Sunarto Quek
• Ngee Ann Polytechnic

2
Content

• Technology domains in solving robotic problems
• Case study Robot Colony
• Collecting pellets
• Differentiating pellets
• Searching pellets
• Locating disposing area
• Conclusion
• QA

3
Technology Domains

• Robotic problems
• Can be solved at different technology domains
• Example
• To align an object for grabbing
• Mechanical domain use mechanical guide
• Electronic domain use sensors
• Computation domain use vision
• Lower vs Higher domain
• Lower (mechanical) is simpler but less flexibility

4
Case Study Robot Colony

• Objective
• To collect pellets of two different colours and
  dispose them at their designated place
• Tasks
• To search pellets
• To collect pellets
• To differentiate pellets
• To locate disposing area and dispose the
  collected pellets

5
Collect Pellet

• Subtask 1
• To align gripper with pellet
• Solution
• Use mechanical guide

• Use vision?
• May not be accurate due to
• Uneven colour of a pellet
• Uneven surrounding light and shadow
• Several pellets lump together

6
Collect Pellet

• Subtask 2
• To hold pellet
• Solution
• Use mechanical gate

• Use motors?
• Could be better but extra cost, programming and
  circuitry

7
Differentiate Pellet

• Use vision or colour detector?
• Expensive and may not be accurate due to
  shadowing and uneven colour and lighting
• Use simple infrared sensor
• Notice that blue pellets are much brighter than
  green pellets
• Differentiate by reflected intensity

8
Search

• Subtask 1
• To detect nearby pellets

• Solution
• Two infrared sensors, each looks on the left and
  right side of the robot
• Front sensors not needed as pellet in front will
  be collected as the robot move forward
• Vision?
• Better but must take care of lighting problem

9
Search

• Subtask 2
• Cover unexplored area

• Solution
• Go to centre and circle out
• Continue from last position after disposing
  pellet
• Mapping the arena?
• Need accurate localization
• But not many good landmark

10
Locate Disposing Area

• Subtask
• To find robots orientation
• Solution
• Ensure each turning is about 90 deg
• Remember the orientation
• Error can be corrected by aligning sensors to line

• Compass?
• Better, but must take care of surrounding
  magnetic field

11
Locate Disposing area

• Once orientation is found
• Robot is at the border
• Turn 90 deg and move until the outer front base
  sensor detect lines
• Disposing area is then located

12
Conclusion

• A simple robot colony was built
• No motor required for collecting pellet
• Simple IR sensor to differentiate pellets
• Strategic sensor placement to maximize pellets
  searching
• Robot can be built in a simple way
• By looking for solutions at lower technology
  domain