r'''Alpha Rex API A high-level, object-oriented programming interface to Lego MINDSTORMS NXT's "Alpha Rex" model (see [1] for assembling instructions), along with a small collection of functions demonstrating obvious usage scenarios. 1. http://www.active-robots.com/products/mindstorms4schools/building-instructions.shtml ''' from time import sleep from nxt.brick import Brick from nxt.locator import find_one_brick from nxt.motor import Motor, PORT_A, PORT_B, PORT_C from nxt.sensor import Light, Sound, Touch, Ultrasonic from nxt.sensor import PORT_1, PORT_2, PORT_3, PORT_4 FORTH = 100 BACK = -100 class AlphaRex(object): r'''A high-level controller for the Alpha Rex model. This class implements methods for the most obvious actions performable by Alpha Rex, such as walk, wave its arms, and retrieve sensor samples. Additionally, it also allows direct access to the robot's components through public attributes. ''' def __init__(self, brick='NXT'): r'''Creates a new Alpha Rex controller. brick Either an nxt.brick.Brick object, or an NXT brick's name as a string. If omitted, a Brick named 'NXT' is looked up. ''' if isinstance(brick, basestring): brick = find_one_brick(name=brick) self.brick = brick self.arms = Motor(brick, PORT_A) self.legs = [Motor(brick, PORT_B), Motor(brick, PORT_C)] self.touch = Touch(brick, PORT_1) self.sound = Sound(brick, PORT_2) self.light = Light(brick, PORT_3) self.ultrasonic = Ultrasonic(brick, PORT_4) def echolocate(self): r'''Reads the Ultrasonic sensor's output. ''' return self.ultrasonic.get_sample() def feel(self): r'''Reads the Touch sensor's output. ''' return self.touch.get_sample() def hear(self): r'''Reads the Sound sensor's output. ''' return self.sound.get_sample() def say(self, line, times=1): r'''Plays a sound file named (line + '.rso'), which is expected to be stored in the brick. The file is played (times) times. line The name of a sound file stored in the brick. times How many times the sound file will be played before this method returns. ''' for i in range(0, times): self.brick.play_sound_file(False, line + '.rso') sleep(1) def see(self): r'''Reads the Light sensor's output. ''' return self.light.get_sample() def walk(self, secs, power=FORTH): r'''Simultaneously activates the leg motors, causing Alpha Rex to walk. secs How long the motors will rotate. power The strength effected by the motors. Positive values will cause Alpha Rex to walk forward, while negative values will cause it to walk backwards. If you are unsure about how much force to apply, the special values FORTH and BACK provide reasonable defaults. If omitted, FORTH is used. ''' for motor in self.legs: motor.run(power=power) sleep(secs) for motor in self.legs: motor.idle() def wave(self, secs, power=100): r'''Make Alpha Rex move its arms. secs How long the arms' motor will rotate. power The strength effected by the motor. If omitted, (100) is used. ''' self.arms.run(power=power) sleep(secs) self.arms.idle() def wave_and_talk(): r'''Connects to a nearby Alpha Rex, then commands it to wave its arms and play the sound file 'Object.rso'. ''' robot = AlphaRex() robot.wave(1) robot.say('Object') def walk_forth_and_back(): r'''Connects to a nearby Alpha Rex, then commands it to walk forward and then backwards. ''' robot = AlphaRex() robot.walk(10, FORTH) robot.walk(10, BACK) def walk_to_object(): r'''Connects to a nearby Alpha Rex, then commands it to walk until it approaches an obstacle, then stop and say 'Object' three times. ''' robot = AlphaRex() while robot.echolocate() > 10: robot.walk(1, FORTH) robot.say('Object', 3) if __name__ == '__main__': walk_to_object()