运动学习与控制-学习笔记（三）——运动控制理论

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一、理解控制理论以及两个重要概念

1.Motor Control Theory

• 理论的概念
  A theory helps us understand phenomena and explains the reasons why these phenomena exist or behave as they do.

• 好的理论需要
  1）精准描述一大类观察
  2）明确预计出未来观察的结果

2.两个重要概念：Coordination,Degree of Freedom Problem

• Coordinatin协调
  Coordination is the patterning of head, body, and limb movements relative to the patterning of environmental objects and events.
  强调：Patterning模式不仅仅只针对技术娴熟的人，无论技术如何，都有可能产生pattern.
  描述-角角图

• 角角图的理解
  ……
  ……
  

• Degree of Freedom Problem,DoF自由度问题
  the number of independent components of in a control system and the number of ways each component can vary.
  关键：controy problem, complex system, specific result, determining how to contrain the system’s many DoFs

二、Open-loop vs. Closed-loop Control system,及运动领域合理举例

1.定义

• Open-loop Control System开环控制系统：a control system in which all the information needed to initiate and carry out an action as planned is contained in the initial instructions to the effectors.

• Closed-loop Control system闭环控制系统：a system of control in which, during the course of an action, feedback is compared against a standard or reference to enable an action to be carried out as planned.

• 判断标准 ：

• 反馈的有无，反馈可使控制中心及时的修正运动。

• 或者是否产生可利用的反馈，若反馈不是必要的或没有足够的时间利用反馈，指令中心已提供完成运动的全部信息，则运动控制系统仍属于开环控制系统。

• 闭环控制系统中运动指令只用来起始动作，执行和完成由反馈信息支配。
  

• 强调与Open/Close Motor skills 的区别
  Open/Close Motor skills判断标准：环境的变化，与Open/Close control system没有相关性。

2.举例

Open-loop Control System:
足球运动中守门员防守点球、100米冲刺跑
Close- loop Control System:
长跑运动员长跑中配速控制、三级跳远踏板前步幅等调整和踏板后重心等调整

三、两种控制理论

1.Motor Program Theory运动程序理论

• Motor program 运动程序
  a memory-based construct that controls coordinated movement
• General motoe program(GMP) 通用运动程序
  a class of actions,which is a set of different actions having a common but unique set of features
• Invariant Features 固定特征
  the basis of what is stored, movement-related features, fundamental pattern of the class of actions, does not vary from one performance to another
• Parameters 参数
  movement-related features,added to the memory,be varied from one performance to another

2.Dynamic System Theory

• 稳定态 stable refers to behavioral steady states
• 吸引子 a behavior occurs when system is allowed to operate in a preferred manner
• 有序参数和控制参数
• 自组织
  when certain conditions characterize a situation,a specific stable pattern of bahavior emerges.
• 协调结构
  skilled action,nervous constrains specific collections of muscles and joints to action cooperatively
  （可以使内在的，或者后天联系所得）
• 知觉-运动耦合 知觉变量和动作变量相互作用，使某一动作的特定运动状态和知觉变量的特定特征相一致。

四、作业

1.Open-Loop 和 Close-Loop 控制系统各举一个例子，并指出其是 Open or Close Motor Skill。
答：
Open-Loop 控制系统：100米跑，因其运动开始时指令中心已经决定了运动过程，得到的一定程度的反馈不足以被利用，故为Open-Loop Control System；因进行时运动环境中会有来自对手的一定程度的变化干扰，所以此运动技巧是Open Montor Skill。
Close-Loop 控制系统：三级跳远，因踏板前步幅等调整和踏板后重心等调整依赖肌群的反馈和指令中心应答，故为Close-Loop Control System;因三级跳远进行时运动环境较为稳定，所以此运动技巧为Close Motor Skill。
2.尝试用Motion Program Theory 以及 Dynamic System Theory取描述接住球这套动作（提示：球飞行时间过了75%的样子，手会做好抓的准备，参数自己设置）。
答：
Using Motion Program Theory:
I think pass is a GMP. It controls a class of actions.For example,when we distinguish it by passing ways,we can get lobbing pass,triangular pass and ground pass,when we distingush it by a parameter named velocity,we can get quick pass,medium speed pass and slow pass and so on.
Next I will discribe the general pass action by its relative time.
First,when the server takes the ball and holds it in front of the chest,the receiver sets his pose and has a psychological preparation for receiving the ball.I call it preparation phase.
Then,from the server throws out the ball to the time when the ball flies till 75% time,I call it modification phase.In this phase,the receiver continuously modify his hands’position and receiving angle.
Next,from 75% flying time to the reveiver holds the ball,I call it catching phase.In this phase the receiver activates his hand muscles to hold the ball.
Last,from the receiver catches the ball to he finally holds the ball,I call it buffering phase.The receiver relieves the ball’s motive energy by putting his hands towards his chest in this phase.

Using Dynamic System Theory:
I think pass is a nonlinear behavior because it has many irregular behavior mutations.
For the order parameters,I think the passing ways such as lobbing pass,triangular pass and ground pass can be order parameters,they make the cooperative action patterns reappear.
For the control parameters,I think the ball’s velocity can be a control parameter.When pass is in a high speed,the receiver will put his hand more forward as a buffer against the ball’s motive energy.
According to the control parameters,pass in different speeds have different stability and attractors.The receiver will put his hand more forward is more stable for adjusting the high speed so its a stability in the high speed pattern.And people prefer to adopt the forword hands states to hold the ball,so this stable behivior can be a attractor.
When the receiver is ready to hold the ball,he will have a temporal cooordonation of vision and the hands that enables him to perform eye-hand coordination skills.I think it is the perception-action coupling in pass action pattern.
Furthermore,coordinative structure is accomplished by nervous system which constrains collections of hand and arm muscles and joints to act cooperatively.They can help players to achieve the action goal.

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