Remote Control of Technic Hub

[kueden]

Description
Based on the tools offered by pybricks it is readily possible to fully control the Lego Technic Hub by means of python coding. While autonomous robots have some charm, the python augmented remote control offers the highest level of play fun. The available tool for remote control as described in issue 154: #154 allows for full remote control via keyboard and bluetooth.
This simple car shows the some possiblitites of this tool that go well beyond normal remote control. Tideous jobs like turning the car or making it drive in slalom for scanning for obstacles are readily taken care of by the software.
The presented software can readily be used on any steering based Technic Hub model of Lego. This dramatically increases the play and fun options.

Video
https://youtu.be/ODCDoBJbhtE

Source Code
https://www.bricksafe.com/files/kueden/augmented-rc/augmented%20RC_3.txt

Building instructions
Coming soon. But you can use the software on any Lego Technic Car with Control+

from pybricks.pupdevices import Motor
from pybricks.parameters import Port, Stop
from pybricks.tools import wait, StopWatch
from pybricks.hubs import TechnicHub
from pybricks.parameters import Color
import math
from pybricks.experimental import getchar


drive = Motor(Port.C)
steer = Motor(Port.D)
hub=TechnicHub()
watch = StopWatch()


# calibrate steering by measuring the total range of motion and set the center position
steer.run_until_stalled(-100, then=Stop.COAST, duty_limit=30)
steer.reset_angle(angle=0)
steer.run_until_stalled(100, then=Stop.COAST, duty_limit=30)
b=steer.angle()/2
steer.run_target(100, b, then=Stop.HOLD, wait=True)
steer.reset_angle(angle=0)
# determine the maximum steering range to either side
stmax=b-b*0.3
# Determine the step size in each steering command 
stang=(b-b*0.01)/4
# Set the steering rotation for car rotation
strot=3*stang
# x is the dc power for driving
x=0
# y is the angle for steering
y=0
# The remote control is based on individual key strokes, not permanent pressed keys
# new marks that the software is ready to take a next key stroke
new=True
# key marks the last stroken key
key=None
# nn is the number of "None" keys that have accumulated
nn=100
# rot indicates the rotation direction of the car when rotating on the spot
# rotation on the spot is triggered by "q" (1) or "e" (-1). Zero is no rotation.
rot=0
# there are different modes for driving with augmented control 0 is standard
mode=0




while True:
    c = getchar()
    # routine for drive backward
    if c == ord('a') and x >= -100:
        if new:
            x=x-10
            new=False
        nn=0
        key=ord('a')
        rot=0
    # routine for drive forward
    elif c == ord('d') and x <= 100:
        if new:
            x=x+10
            new=False
        nn=0
        key=ord('d')
        rot=0
    # routine for braking
    elif c == ord('s'):
        x=0
        rot=0
        
    # routine for steering left
    elif c == ord('l') and y >= -stmax:
        if new:
            y=y-stang
            new=False
        nn=0
        key=ord('l')
        rot=0

    # routine for steering right
    elif c == ord('j') and y <= stmax:
        if new:
            y=y+stang
            new=False
        nn=0
        key=ord('j')
        rot=0
    # routine for centering the steering 
    elif c == ord('k'):
        y=0
        rot=0
    # routine for rotating right
    elif c == ord('q'):
        rot=1
        dir=1
        x=0
        y=0
    # routine for rotating left
    elif c == ord('e'):
        rot=-1
        dir=1
        x=0
        y=0
    # counts the number of "None"
    elif c == None:
        nn=nn+1
        # counts the number of "None"
    elif c == ord('w'):
        mode=mode+1
        if mode > 2:
            mode=0
        if mode == 0:
            hub.light.on(Color.GREEN)
        if mode == 1:
            hub.light.on(Color.RED)
            watch.reset()
        if mode == 2:
            hub.light.on(Color.BLUE)
            watch.reset()

    # when enough "None" have accumulated the next keystroke is ready. Values smaller than 500 
    # result in continuous increase of the x and y when key remains ressed
    # values of 500 require individual key strokes
    if c != key and nn >= 500:
        new=True
    # execution of routine for rotating left
    if rot == 1:
        steer.track_target(dir*strot)
        drive.run_time(dir*500, 1000, then=Stop.HOLD, wait=True)
        dir=dir*-1
    # execution of routine for rotating right
    if rot == -1:
        steer.track_target(-dir*strot)
        drive.run_time(dir*500, 1000, then=Stop.HOLD, wait=True)
        dir=dir*-1
# send drive and steer commands
        
    if mode == 1 and y == 0:
        # read the timer
        t = watch.time()
    # determine the rist variation of the scan based on the sinus function
        ys=strot*math.sin(t*0.003)
        drive.dc(x)
        steer.track_target(ys)

    elif mode == 2 and y == 0:
        # read the timer
        t = watch.time()
    # determine the rist variation of the scan based on the sinus function
        ys=strot*(math.sin(t*0.003))**3
        xs=x*(math.cos(t*0.003))**2
        drive.dc(xs)
        steer.track_target(ys)            
        
    else:    
        drive.dc(x)
        steer.track_target(y)