Encoder Odometry Problems

asked 2020-06-23 05:14:15 -0600

jarain78 gravatar image

updated 2020-06-24 02:02:54 -0600

Hi, I have a problem with my robot and its encoders, basically, I'm trying to get the position in (X, Y) using encoders. I make a quadrature encoder and it generates 1440 tick per revolution and the wheel radius is 30 mm. Now, when I plot the calculated robot position through the encoder position, based on this code:

def get_position_using_encoders(self, dt, left_enc, right_enc, yaw=0, verbose=False):

    # Calculate odometry

    if self.enc_left != None:

        dright_1 = (right_enc - self.enc_right)
        dleft_1 = (left_enc - self.enc_left)  

        dright = dright_1 / self.tick_per_meter
        dleft = dleft_1 / self.tick_per_meter

    else:
        dright = 0
        dleft = 0

    dxy_ave = (dright + dleft) / 2.0

    self.dth += (dright - dleft) / self.wheel_track

    y += dxy_ave * cos(self.dth + yaw)
    x += dxy_ave * sin(self.dth + yaw)

    self.enc_right = right_enc
    self.enc_left = left_enc

    return x, y

I have this graph:

image description

Honestly, I don't know why I have this.

Thanks

jarain78

edit retag flag offensive close merge delete

Comments

Where physically does your encoder data come from? Is it simulated or really from encoders? Looks like corrupted data. Is it repeatable?

billy gravatar image billy  ( 2020-06-23 19:00:28 -0600 )edit

Hey, Billy, thanks for the comment. The encoder is real, I use the external interruption of an Arduino to count the encoder and send the count to my robot.

Regards

jarain78

jarain78 gravatar image jarain78  ( 2020-06-24 02:10:54 -0600 )edit

Isolate your encoder data from the data transportation. Put a repeating number on the serial line between each encoder update and see if that number ever shows up corrupted or implement a simple CRC type check. Either your counting is failing or the communication is failing.

billy gravatar image billy  ( 2020-06-24 15:58:30 -0600 )edit

Hey, Billy, thanks for the comment. I solved my problem, it was like you said the data had been corrupted.

Thank you

jarain78 gravatar image jarain78  ( 2020-07-02 02:15:16 -0600 )edit
add a comment