vesc.py

# Contains functions for defining VESC class object.
# Obtained from : https://drive.google.com/drive/folders/1SBzChXK2ebzPHgZBP_AIhVXJOekVc0r3

import time

import donkeycar as dk


class VESC:
    ''' 
    VESC Motor controler using pyvesc
    This is used for most electric scateboards.

    inputs: serial_port---- port used communicate with vesc. for linux should be something like /dev/ttyACM1
    has_sensor=False------- default value from pyvesc
    start_heartbeat=True----default value from pyvesc (I believe this sets up a heartbeat and kills speed if lost)
    baudrate=115200--------- baudrate used for communication with VESC
    timeout=0.05-------------time it will try before giving up on establishing connection

    percent=.2--------------max percentage of the dutycycle that the motor will be set to
    outputs: none

    uses the pyvesc library to open communication with the VESC and sets the servo to the angle (0-1) and the duty_cycle(speed of the car) to the throttle (mapped so that percentage will be max/min speed)

    Note that this depends on pyvesc, but using pip install pyvesc will create a pyvesc file that
    can only set the speed, but not set the servo angle. 

    Instead please use:
    pip install git+https://github.com/LiamBindle/PyVESC.git@master
    to install the pyvesc library
    '''

    def __init__(self, serial_port, percent=.2, has_sensor=False, start_heartbeat=True, baudrate=115200, timeout=0.05, steering_scale=1.0, steering_offset=0.0):

        try:
            import pyvesc
        except Exception as err:
            print("\n\n\n\n", err, "\n")
            print(
                "please use the following command to import pyvesc so that you can also set")
            print("the servo position:")
            print("pip install git+https://github.com/LiamBindle/PyVESC.git@master")
            print("\n\n\n")
            time.sleep(1)
            raise

        assert percent <= 1 and percent >= - \
            1, '\n\nOnly percentages are allowed for MAX_VESC_SPEED (we recommend a value of about .2) (negative values flip direction of motor)'
        self.steering_scale = steering_scale
        self.steering_offset = steering_offset
        self.percent = percent

        try:
            self.v = pyvesc.VESC(serial_port, has_sensor,
                                 start_heartbeat, baudrate, timeout)
        except Exception as err:
            print("\n\n\n\n", err)
            print(
                "\n\nto fix permission denied errors, try running the following command:")
            print("sudo chmod a+rw {}".format(serial_port), "\n\n\n\n")
            time.sleep(1)
            raise

    def run(self, angle, throttle):
        self.v.set_servo((angle * self.steering_scale) + self.steering_offset)
        self.v.set_duty_cycle(throttle*self.percent)