运动控制与学习 学习笔记（四）——复杂技能的表现特征、本体感觉及视觉

1.理解Speed Accuracy Trade-off 现象及其与Fitts'Law的关系1.1Speed Accuracy Trade-off 速度准确性权衡1.2Fitts'Law 菲兹定律 2.Prehension 够取2.1Defination:2.2 Prehension & Fitt's Law2.3 视觉作用2.4 实践指导 3.Handwriting 书写3.1 Motor equivalence 运动等效性3.2 Vision & Handwriting 4.Bimanual Coordination 双手协调4.1 Symmetric VS. Asymmetric 对称、不对称4.2 Bimanual Coordination Preference 双手协调偏好4.3 Control Theory for this skill4.4 实践指导 5.Catching/Striking Moving Object 抓、击打移动物体5.1 Compared to Prehension5.2 Three Phases of Catching an Object5.3 Vision and Catching5.4 Vision and Striking 6.Locomotion 移动6.1 The Rhythmic Structure 节律结构6.2 Head Stability 头部稳定6.3 Vision and Locomotion 7.作业

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1.理解Speed Accuracy Trade-off 现象及其与Fitts’Law的关系

1.1Speed Accuracy Trade-off 速度准确性权衡

速度与准确性需求相互影响 小组垒球投掷实验

1.2Fitts’Law 菲兹定律

MT = a + b * ID = a + b * log_[2] (2D/W) D:distance W:target size ID:index od difficulty MT:the average time to complete the movement

2.Prehension 够取

2.1Defination:

The action of reaching for and grasping of an object that may be station or moving.

三部分组成：

Transport 移动(运达）Grasp抓握Object manipulation 物品操纵

前两组成部分的关系——temporally coupled and interact synergistically cooperatively 时间耦合、合作交互：

物品大小、与手距离同时影响了： 手指与拇指距离张最大的发生时间、手移动的速度变化

无论物品大小、与手距离怎样： 手指和拇指间距离张最大及抓发生时间均在总动作时间（MT）的2/3

移动和和抓握部分的运动学特征都在不断修正——目标移动或躲避障碍

2.2 Prehension & Fitt’s Law

Movement distance and object width influenced movement time during prehension in accordance with the predictions of Fitts law(Bootsma,et al 1994)距离、物品宽度影响运动时间As objects decrease in siza, the amount of time incolced in the deceleration phase of the movement increases.物品尺寸越校，减速环节（靠近物品环节）的时间增加Drinking from a mug test.(Latash and Jaric, 2002)ID除了与物品尺寸，距离有关，还与容器中液体量有关 ID = mug size/water level *(公式是死的人是活的，ID是一个规定的数值，动作难度不一定随ID增大而变大)

2.3 视觉作用

for Transport —— similar to speed Accuracy Skills —— aiming tasks for Grasp&object manipulation —— Provide visual feedbacks

2.4 实践指导

Object manipulation 环节会影响Prehension 的运动学和动力学特征

物品、环境特征影响着Prehension的各个环节（Fitts’ law）

Transport & Grasp 两个环节相互影响

训练Prehension动作时，要考虑物品操纵环节，即运动功能/目标

需要设计不同物品、环境特征进行较完整地训练

无法将三个环节分开独立训练

3.Handwriting 书写

3.1 Motor equivalence 运动等效性

def:多种环境和场景下完成运动目标 的能力

3.2 Vision & Handwriting

总结：

to help the writer control the overall spatial arrangement of words on a horizontal line 帮助把字写在水平线上to help the writer produce accurate handwriting patterns 辅助规范化书写

4.Bimanual Coordination 双手协调

4.1 Symmetric VS. Asymmetric 对称、不对称

略

4.2 Bimanual Coordination Preference 双手协调偏好

tempora basis for rhe coordination of two arms with the similar movement times not only two targets with the same ID values but also to two targets that have different ID values the more difficult task influenced the less difficult task

4.3 Control Theory for this skill

Motor Program Thoery Dynamic System Theory 见运动控制理论

4.4 实践指导

Symmetric, relatively easy Asymmetric, more challenging —— approprite instruction, feedback,& practice

5.Catching/Striking Moving Object 抓、击打移动物体

5.1 Compared to Prehension

Prehension:

stationary objectinvolves doing something with the grasped object(包含多) Catching:moving objectthe grasp of the object ends the action

5.2 Three Phases of Catching an Object

5.3 Vision and Catching

Amount of visual contract time 注视时长 两个关键时刻持续注视：飞行初期、接触到手前Tau 物体与人眼接触时间 通常用tau来衡量TTC TTC(Time To contract) = Z/VVision of the hands 手的可见性 经验+手的可见性影响Catching表现

5.4 Vision and Striking

Vision and Baseball Batting only a point tracked longerVision and Table Tennis Striking initiation of the swing provides online information

6.Locomotion 移动

6.1 The Rhythmic Structure 节律结构

走、跑有着不同的戒律结构上下肢之间存在于速度相关的节律性

6.2 Head Stability 头部稳定

a goal of motor control system is to maintain head stability least amount of head movement occurs at the preferred walking speed Because:

Head contains the complex of sensory and motor nervous system componentOptimizes the use of visioneg. children with cerebral palsy and adults with neurological impairment

6.3 Vision and Locomotion

contacting objectsavoiding contact with object

7.作业

1.Read “POINTS FOR THE PRACTITIONER” in the English texbook, page 170. 选择其中两个（第二点除外），利用课上讲的内容作为支撑，解释一下为什么这样做。 1）When helping people initially learn speed-accuracy skills, you should emphasize achieving the accuracy goal more than the speed goal. Because people who initially learn a skill is always lack of experiences and complete the task difficultly. As the speed-accuracy trade-off shows that if the movement must be as accuracy as possible, people move at a slow rate of speed than when accuracy is not important. So we emphasize accuracy goal more at first.When people adjust the movement and have a better skill, then it’s time for us to rise speed.

3）When helping people inhabilitate their prehension capbilities, provide functional prehension activities that include a wide range of object sizes, reach distances, grip configurations, and object uses. Because as the Fitt’s low shows that the aiming object with wide size and long distance is easy to prehension.In addition, more grip configurations and uses of the aiming object also reduce the difficulty of the task.When people inhabilitate their prehension capbilities, easy targets are appropriate.

a)描述一种够取场景，并写出各个环节 b)描述每个环节的动作特征及其如何根据够取场景不同而改变 c)讨论名词“temporal coupling(时间耦合)”，以及其与够取运动技能的关系

答： a)课堂上够取眼镜：够取眼镜分三个环节，分别是运达、抓握和物品操纵。首先我的视觉锁定眼镜物体，伸出手臂朝向眼镜移动，由于眼镜位置确定，体积相对较大，我的手臂移动迅速，在运动中大拇指与四指张开，直到触及眼镜，手掌合拢，抓握眼镜，接着操纵眼镜做出意向性动作，够取完成。此过程中手掌合拢时刻为抓握总时长的三分之二处。

b)运达环节：视觉定位，伸出手臂，调整方向，张开手掌；抓握环节：合拢手掌，包裹物品，控制手部力量；物品操纵环节：根据抓握意向及物品形状大小调整手部肌肉用力大小方向。 物品时空间不同，运达时定位即伸手方向会响应改变。物品大小及距离不同，运达时手的移动速度和手指张开距离的最大时间会发生改变。物品形状重量不同，抓握、操纵时手掌肌肉的发力角度和用力力度都会响应改变。

c)时间耦合是够取运动技能中前两环节——运达和抓握之间的关系。物品大小、与手距离同时影响了手指与拇指距离张最大的发生时间、手移动的速度变化。但无论物品大小、与手距离怎样，手指和拇指间距离张最大及抓发生时间均在总动作时间（MT）的2/3。还有在够取运动进行时，移动和和抓握部分的运动学特征都在不断修正，以应对目标移动或躲避障碍物。