Version: 2017.4

2D 目标关节 (Target Joint 2D)
2D 恒定力 (Constant Force 2D)

# 2D 车轮关节 (Wheel Joint 2D)

## 属性

Enable Collision 连接的两个对象能否相互碰撞？选中此复选框表示“能”。
Connected Rigid Body 在此处指定该关节连接到的另一个对象。如果将此属性保留为 None__，此关节的另一端将固定到空间中由 Connected Anchor__ 设置所定义的点。选择字段右侧的圆圈可查看要连接到的对象的列表。
Auto Configure Connected Anchor 选中此框可为该关节连接到的另一个对象自动设置锚点位置。（选中此框将无需填写 Connected Anchor 字段。）
Anchor The place (in terms of X, Y co-ordinates on the RigidBody) where the end point of the joint connects to this object.
Connected Anchor The place (in terms of X, Y co-ordinates on the RigidBody) where the end point of the joint connects to the other object.
Damping Ratio The degree to which you want to suppress spring oscillation in the suspension: In the range 0 to 1, the higher the value, the less movement.
Frequency The frequency at which the spring in the suspension oscillates while the objects are approaching the separation distance you want (measured in cycles per second): In the range 0 to 1,000,000 - the higher the value, the stiffer the suspension spring.
Angle The world movement angle for the suspension.
Use Motor Apply a motor force to the wheel? Check the box for yes.
Motor
Motor Speed Target speed (degrees per second) for the motor to reach.
Maximum Motor Force Maximum force applied to the object to attain the desired speed.
Break Force Specify the force level needed to break and so delete the joint. Infinity means it is unbreakable.
Break Torque Specify the torque level needed to break and so delete the joint. Infinity means it is unbreakable.

## 详细信息

（另请参阅 2D 关节中的详情和提示以了解所有 2D 关节的有用背景信息。）

2D 车轮关节的行为就像 2D 滑动关节（不包括其电机或限制约束）和 2D 铰链关节（不包括其限制约束）的组合。

• 高（1,000,000 为最高）__Frequency__ == 僵硬悬架。

• 高（1 为最高）__Damping Ratio__ == 几乎不动的悬架。

• Frequency == 松弛悬架。

• 低 __Damping Ratio__== 移动的悬架。

• 与两个刚体对象上两个锚点之间的一条指定线保持相对线性距离为零。
• 保持两个刚体对象上的两个锚点之间的角速度。（通过 Maximum Motor Speed 选项设置速度，并通过 Maximum Motor Force 设置最大扭矩。）

• 在模拟车轮时，用电机驱动这些车轮，并用一条线定义允许的悬架移动。

## 提示

2D 车轮关节的行为不同于车轮碰撞体：

Frequency 为零是特殊情况：这种情况下会产生最大刚度的弹簧。

2D 目标关节 (Target Joint 2D)
2D 恒定力 (Constant Force 2D)