Pololu Sample Project: Simple Hexapod Walker, Manual

Page: 18 / 21

5. Using a Script for Obstacle Avoidance
The Micro Maestro has an internal scripting language that can store sequences, read
sensors, and link everything together to form intelligent behaviors, making your hexapod
truly autonomous. For complete documentation on the scripting language, see
Section 6
of
the Micro Maestro User’s Guide
[http://www.pololu.com/docs/0J40]
.
Once you have set up all of your basic gaits, erase your script, then click the “Copy All
Sequences to Script” button on the Sequence tab. This button adds a set of subrountines
that you can use to access the various gaits from within a script.
You can then call these subroutines from your script. For example,
begin
forward
left
repeat
will cause the hexapod to repeatedly step forward then turn left, over, and over. You will
probably want to take into account the sensor readings, which can be accessed using the
GET_POSITION command. Here is an example of a very simple program that uses the sensor
readings to try to avoid objects – customize this to get the behavior you want!
start:
# back up if both sensors see an object
left_sensor right_sensor logical_and
if back back back goto start endif
# back up and turn right if the left sensor sees an object
left_sensor if back right right right goto start endif
# back up and turn left if the right sensor sees an object
right_sensor if back left left left goto start endif
# otherwise, if there is nothing ahead, walk forward
forward
goto start
# returns true if the left sensor sees an object
sub left_sensor
4 get_position 512 less_than
return
# returns true if the right sensor sees an object
sub right_sensor
3 get_position 512 less_than
return
### Sequence subroutines: ###
# back
sub back
100 4992 5312 5056 frame_0_1_2 # Frame 0
120 7168 6976 frame_0_2 # Frame 1
100 6528 frame_1 # Frame 2
120 4992 5056 frame_0_2 # Frame 3
return
# forward
sub forward
100 7168 5312 6976 frame_0_1_2 # Frame 1
120 4992 5056 frame_0_2 # Frame 2
100 6528 frame_1 # Frame 3
120 7168 6976 frame_0_2 # Frame 0
return
# left
sub left
100 7168 5312 5056 frame_0_1_2 # Frame 0
150 4992 6976 frame_0_2 # Frame 1
Sample Project: Simple Hexapod Walker © 2001–2010 Pololu Corporation
5. Using a Script for Obstacle Avoidance Page 18 of 21