TypeError : object 'line' is not a tuple or list

I tried to run this code on OpenMV IDE, but the system suddenly says TypeError and I don’t know how to fix this.

This is the code. The TypeError box appears on the code line ( img.draw_line(l, color=(127)) # Draw lines)

# Autonomous rover code by Chris Anderson, 3DR, DIY Robocars
# Copyrigbt 2017
# Released under a BSD 2.0 Open Source Licence

import sensor, image, pyb, math, time
from pyb import Servo
from pyb import LED

s1 = Servo(1) # P7 Motor
s2 = Servo(2) # P8 Steering
print (s1.calibration()) # show throttle servo calibration
cruise_speed = 0 # how fast should the car drive, range from 1000 to 2000
steering_gain = 500
kp = 0.8   # P term of the PID
ki = 0     # I term of the PID
kd = 0     # D term of the PID

red_led   = LED(1)
green_led = LED(2)
blue_led  = LED(3)
ir_led    = LED(4)

old_error = 0
measured_angle = 0
set_angle = 90 # this is the desired steering angle (straight ahead)
p_term = 0
i_term = 0
d_term = 0
old_time = pyb.millis()

def led_control(x):
    if   (x&1)==0: red_led.off()
    elif (x&1)==1: red_led.on()
    if   (x&2)==0: green_led.off()
    elif (x&2)==2: green_led.on()
    if   (x&4)==0: blue_led.off()
    elif (x&4)==4: blue_led.on()
    if   (x&8)==0: ir_led.off()
    elif (x&8)==8: ir_led.on()

def constrain(value, min, max):
    if value < min :
        return min
    if value > max :
        return max
    else:
        return value

def steer(angle):
    global steering_gain
    s1.angle(angle) # steer
    pyb.delay(10)

def update_pid():
    global old_time, old_error, measured_angle, set_angle
    global p_term, i_term, d_term
    now = pyb.millis()
    dt = now - old_time
    error = set_angle - measured_angle
    de = error - old_error

    p_term = kp * error
    i_term += ki * error
    i_term = constrain(i_term, 0, 100)
    d_term = (de / dt) * kd

    old_error = error
    output = p_term + i_term + d_term
    output = constrain(output, -50, 50)
    return output

sensor.reset() # Initialize the camera sensor.
sensor.set_pixformat(sensor.GRAYSCALE) # or sensor.RGB565
sensor.set_framesize(sensor.QQVGA) # or sensor.QVGA (or others)
clock = time.clock() # Tracks FPS.
#s1.pulse_width(2000)  # initialize the motor controller with a high signal for a second
#pyb.delay(1000)
#s1.pulse_width(1000) # return motor controller to low/off throttle
while(True):
    led_control(2)
#    s1.speed(120)   Start motor; currently disabled while I use RC for throttle
#    pyb.delay(10)
    clock.tick() # Track elapsed milliseconds between snapshots().
    img = sensor.snapshot() # Take a picture and return the image.
    img.find_edges(image.EDGE_CANNY, threshold=(60, 150))  # Find edges
    lines = img.find_lines(threshold=35) # Find lines.
    counter = 0
    totalangle = 0
    for l in lines:
        img.draw_line(l, color=(127)) # Draw lines
    if lines:
        if (l[2]-l[0]) != 0: # don't allow vertical lines (undefined arctan)
            angle = -math.atan2(-(l[3]-l[1]),(l[2]-l[0])) # arctan (deltaY/deltaX); we use atan2 so we can tell what quadrant it's in
            angle = math.degrees(angle) # convert from radians to degrees
        if angle < 140 and angle > 40: # ignore lines that are mostly horizontal
                totalangle = totalangle + angle  # add up all the line angles so we can average them
                counter = counter + 1
        if counter != 0:
            now = pyb.millis()
            if  now > old_time + 1.0 :  # time has passed since last measurement
                measured_angle = totalangle/counter  # average of angles
                steer_angle = update_pid()
                old_time = now
                steer (steer_angle)
                print(str(measured_angle) + ', ' + str(set_angle) + ', ' + str(steer_angle))
#           s1.pulse_width(cruise_speed) # move forward at cruise speed; currently disabled while I run throttle with RC

You need to call .line() on “l”.

img.draw_line(l.line(), color=(127)) # Draw lines

find_lines returns a “Line” object http://docs.openmv.io/library/omv.image.html?highlight=find_lines#class-line-line-object
but draw_line needs a tuple.

Once I get around to updating the draw methods I can make this less error prone.

Thank you aakoch for the information. :stuck_out_tongue: But it still does not work. Thanks for the help btw

Can’t wait to hear from you kwagyeman :smiley:

What’s the error you are getting now?

Oh, its functional. It was my mistake.
img.draw_line(l.line(), color=(127)) # Draw lines, i mistakenly typed img.draw_line(l.lines(), color=(127)) # Draw lines. Sorry for that. Thank you aakoch.

Although, the camera detects, my rover did not move. I have already adjusted the cruising speed to 1500. The motor still did not run.

Hi, find where the code drive power to the motor and print out what you are telling the motor to do. See what’s going on. I can help more with a specific question.

Thank you kwagyeman :smiley: . I’ll post it here once I’ve found the code

s1 = Servo(1) # P7 Motor
s2 = Servo(2) # P8 Steering
print (s1.calibration()) # show throttle servo calibration
cruise_speed = 1500 # how fast should the car drive, range from 1000 to 2000
steering_gain = 500
kp = 0.8   # P term of the PID
ki = 0     # I term of the PID
kd = 0     # D term of the PID



def steer(angle):
    global steering_gain
    s1.angle(angle) # steer
    pyb.delay(10)

def update_pid():
    global old_time, old_error, measured_angle, set_angle
    global p_term, i_term, d_term
    now = pyb.millis()
    dt = now - old_time
    error = set_angle - measured_angle
    de = error - old_error

    p_term = kp * error
    i_term += ki * error
    i_term = constrain(i_term, 0, 100)
    d_term = (de / dt) * kd

    old_error = error
    output = p_term + i_term + d_term
    output = constrain(output, -50, 50)
    return output



 now = pyb.millis()
            if  now > old_time + 1.0 :  # time has passed since last measurement
                measured_angle = totalangle/counter  # average of angles
                steer_angle = update_pid()
                old_time = now
                steer (steer_angle)
                print(str(measured_angle) + ', ' + str(set_angle) + ', ' + str(steer_angle))
#           s1.pulse_width(cruise_speed) # move forward at cruise speed; currently disabled while I run throttle with RC

I use a small rc smart kit, so the voltage produces may not be high, about 6v.

Hi, this looks likes Chris’s code. Have you tried asking him what’s going on? I’m not sure where to start to help you. Since that’s a PID loop you kinda need to remove everything but the P part and see if that provides enough drive strength. If so not, increase the P gains until the robot starts to move.