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用时间写自动Time-Based Autonomous

2.1 最简单的方法：spin + wait + stop2.1 The Simplest Method: spin + wait + stop

写自动程序最直觉的方法：让电机转一段时间，然后停下来。The most intuitive way to write autonomous: spin the motors for a set time, then stop.

就像你告诉朋友："往前走 2 秒，然后左转 1 秒"——用时间来控制距离和角度。Like telling a friend: "Walk forward for 2 seconds, then turn left for 1 second" -- using time to control distance and angle.

C++ (VEXcode)

void autonomous() {
    // 第 1 步：前进 2 秒
    LeftMotor.spin(forward, 50, percent);
    RightMotor.spin(forward, 50, percent);
    wait(2, seconds);

    // 第 2 步：停下
    LeftMotor.stop();
    RightMotor.stop();

    // 第 3 步：右转 0.8 秒
    LeftMotor.spin(forward, 40, percent);
    RightMotor.spin(reverse, 40, percent);
    wait(0.8, seconds);

    // 第 4 步：停下
    LeftMotor.stop();
    RightMotor.stop();

    // 第 5 步：再前进 1.5 秒
    LeftMotor.spin(forward, 50, percent);
    RightMotor.spin(forward, 50, percent);
    wait(1.5, seconds);

    // 第 6 步：停
    LeftMotor.stop();
    RightMotor.stop();
}

C++ (VS Code)

void autonomous() {
    // 第 1 步：前进 2 秒
    LeftMotor.spin(forward, 50, percent);
    RightMotor.spin(forward, 50, percent);
    wait(2, seconds);

    // 第 2 步：停下
    LeftMotor.stop();
    RightMotor.stop();

    // 第 3 步：右转 0.8 秒
    LeftMotor.spin(forward, 40, percent);
    RightMotor.spin(reverse, 40, percent);
    wait(0.8, seconds);

    // 第 4 步：停下
    LeftMotor.stop();
    RightMotor.stop();

    // 第 5 步：再前进 1.5 秒
    LeftMotor.spin(forward, 50, percent);
    RightMotor.spin(forward, 50, percent);
    wait(1.5, seconds);

    // 第 6 步：停
    LeftMotor.stop();
    RightMotor.stop();
}

C++ (PROS)

void autonomous() {
    // 第 1 步：前进 2 秒
    left_motor.move(64);   // 64/127 ≈ 50%
    right_motor.move(64);
    pros::delay(2000);     // 2000 毫秒 = 2 秒

    // 第 2 步：停下
    left_motor.move(0);
    right_motor.move(0);

    // 第 3 步：右转 0.8 秒
    left_motor.move(50);
    right_motor.move(-50);
    pros::delay(800);

    // 第 4 步：停下
    left_motor.move(0);
    right_motor.move(0);

    // 第 5 步：再前进 1.5 秒
    left_motor.move(64);
    right_motor.move(64);
    pros::delay(1500);

    // 第 6 步：停
    left_motor.move(0);
    right_motor.move(0);
}

模式很简单：spin → wait → stop，重复这个套路就能组合出各种动作。The pattern is simple: spin -> wait -> stop, repeat this to build any sequence of movements.

2.2 先碰壁：跑 3 次结果不一样2.2 Hit the Wall: Different Results Every Time

用时间控制写完之后，你会发现一个大问题：After writing time-based control, you'll discover a big problem:

问题：每次跑的结果都不一样！Problem: Different results every run!

同一段代码，跑第一次前进了 60 厘米，跑第二次变成 55 厘米，跑第三次又变成 63 厘米。转弯角度也是，有时候转 85 度，有时候转 95 度。Same code: first run goes 60 cm, second run goes 55 cm, third run goes 63 cm. Turning is the same -- sometimes 85 degrees, sometimes 95 degrees.

为什么会这样？因为时间控制依赖太多不稳定的因素：Why does this happen? Because time control depends on too many unstable factors:

电池电量Battery level：满电时电机转得快，电量低时转得慢。同样 2 秒，跑的距离不一样: Motors spin faster on full charge, slower on low battery. Same 2 seconds, different distance
地面摩擦Surface friction：场地不同区域摩擦力不一样，轮子打滑程度不同: Different areas of the field have different friction, wheels slip differently
机器人重量Robot weight：装了新零件后变重，同样速度跑得更慢: Adding new parts makes it heavier, same speed but slower movement
轮子磨损Wheel wear：轮子用久了直径变小，同样转速跑的距离变短: Worn wheels have smaller diameter, same RPM but shorter distance

动手验证Try It Yourself

写一段"前进 2 秒"的代码，在同一块场地上连续跑 3 次。用尺子量每次前进的距离，看看差多少。Write a "drive forward for 2 seconds" program and run it 3 times on the same field. Measure the distance each time with a ruler and see how much it varies.

你会发现：差距可能有 5-10 厘米。在比赛中，这个误差可能让你错过得分物。You'll find: the difference can be 5-10 cm. In a match, this error could make you miss a scoring object.

2.3 时间控制适合什么场景？2.3 When Is Time Control Appropriate?

时间控制虽然不精确，但在某些场景下够用：Time control isn't precise, but it works for certain situations:

比赛前快速调试Quick pre-match testing：先用时间控制跑通流程，再换成编码器控制精调: Get the routine working with time first, then switch to encoder control for fine-tuning
不需要精确定位的动作Actions that don't need precision：比如"冲过去撞一下"，差几厘米无所谓: Like "rush forward and ram something" -- a few cm off doesn't matter
机构动作Mechanism actions：比如"夹爪关闭 0.5 秒"，误差不大: Like "close the claw for 0.5 seconds" -- small error is acceptable

关键认识Key Takeaway

时间控制是自动程序的起点，但不是终点。下一节我们会学用编码器替代时间，让动作精确可重复。Time control is a starting point for autonomous programs, but not the final solution. Next lesson we'll learn to use encoders instead of time for precise, repeatable movements.

检查点：写一段时间控制自动Checkpoint: Write a Time-Based Autonomous

用时间控制写一段自动程序：前进 1 秒 → 停下 → 左转 0.5 秒 → 停下。Write a time-based autonomous program: drive forward 1 second -> stop -> turn left 0.5 seconds -> stop.

写完之后回答：时间控制最大的缺点是什么？After writing, answer: What is the biggest drawback of time control?