import numpy as np

class ConstantVelocityPolicy:
    def __init__(self, target_speed=50):
        self.step_num = 0

    def act(self):
        self.step_num += 1
        # 简单的前进策略：直行 + 较大油门
        steering = 0.0  # 直行
        throttle = 0.5  # 中等油门，让车辆有明显运动
        
        return [steering, throttle]