def get_normal_neutral_acceleration(acceleration, bias_value):
    """
    Bias adjust the acceleration and then normalize it by the max of the
    signal

    Args:
        acceleration: pandas Series numpy array of acceleration data
        bias_value: Value to use for bias adjusting the data
    Returns:
        bias_adj: bias adjusted and absolute value of acceleration
    """
    # Bias adjust for gravity and absolute value
    bias_adj = abs(acceleration - bias_value)
    return bias_adj