Chapter 5 - Tactile Navigation with Whiskers

In this chapter, you will build tactile switches, called whiskers, onto your BOE-Bot and test them. You will then program the BOE-Bot to monitor the states of these switches, and to decide what to do when it encounters an obstacle. The end result will be autonomous navigation by touch.


By the time you complete this section you will be able to:

  1. Understand what sensors are and why they are used.
  2. ch5Mount the tactile switches, called whiskers, onto the Boe-Bot and test them.
  3. Understand how the Boe-Bot knows when the whiskers have detected an obstacle.
  4. Connect the sensor circuit to the appropriate I/O register. Understand what type of electrical connection is made with the sensor.
  5. Understand how to check Input Registers and display the values in them. Know what values to expect when the sensor detects an object and when it doesn't.
  6. Understand and use the DEBUG CRSRXY command.
  7. Modify the circuit for Boe-Bot and the programming so that LEDs light up when the whiskers detect an object.
  8. Program the Boe-Bot to monitor the state of the switches, and decide what to do when it encounters an obstacle.
  9. Operate the Boe-Bot with autonomous navigation by touch using the whiskers.
  10. Program the Boe-Bot to detect corners, and decide what to do to get out of a corner.
  11. Program nested IF..THEN commands and understand how the commands work – the logic used.
  12. Program the use of subroutines and understand how the logic works.


  1. View the videos in the video section of this lesson.
  2. Read and follow the instructions in Robotics with the Boe-Bot Chapter 5.
  3. Complete the Boe-Bot activities assigned by your instructor, following the step-by-step tutorials and videos in the Activities section below. If self-study, do all the "Your Turn" parts for each activity in the chapter. (Note: It is only by typing in the commands that you truly begin to understand programming. So don't short change yourself.)
  4. Review the Key Points or FAQs below.
  5. Answer the questions in the worksheet document.
  6. Complete the Programming Exercises at the end of the chapter and fill out the worksheet for them.
  7. Complete the Projects at the end of the chapter and fill out the worksheet for them.
  8. Check your answers. When complete, turn in the Worksheet Doc to your instructor (print, email or other method defined by your instructor). Self-study students can optionally send to a parent, mentor or friend.


Activity / Process

Key Points or FAQs:

What is the CRSRXY command and why would you use it?

The CRSRXY command lets you position the cursor and the text that is written anywhere on the debug window. It's useful if you want to line up columns of data.

How does a program go and return from a subroutine?

The command GoSub is used to direct a program to go to a subroutine and execute all the commands it finds there. It then automatically returns to the next command that appears after the GoSub command.