Are arm trajectories planned in kinematic or dynamic coordinates? An adaptation study
Are arm trajectories planned in kinematic or dynamic coordinates? An adaptation study
复制标题
手臂轨迹是在运动学坐标还是动态坐标中规划的？
DOI：
10.1007/bf00241505
复制
发表时间：
1995
影响因子：
2
通讯作者：
Michael I. Jordan
中科院分区：
文献类型：
--
作者：
D. Wolpert;Zoubin Ghahramani;Michael I. Jordan
点对点的人类手臂运动有几个不变的特征：轨迹往往是直的，平滑的，并具有钟形的速度轮廓。考虑这些数据的一种方法是通过优化理论;移动被隐含地指定为成本函数的最优值，例如，集成加加速度或扭矩变化。轨迹规划的优化模型以及优化框架中没有提到的模型通常分为两大类--运动学坐标中指定的模型和动态坐标中指定的模型。为了区分这两种可能性，我们研究了人工视觉反馈对平面双关节手臂运动的影响。在自定步调的点对点手臂运动的手的位置的视觉反馈被改变，以增加感知的曲率的运动。扰动在运动的两端为零，在运动的中点达到最大值。由手坐标运动学指定的成本函数预测适应增加的曲率，以减少视觉曲率，而动态指定的成本函数预测在底层轨迹规划器中没有适应，只要仍然可以实现运动的最终目标。我们还研究了减少横向运动中感知曲率的影响，这些运动通常是轻微弯曲的。只有当所需的轨迹在运动学坐标中指定并且实际上是弯曲的时，才应该在这种情况下看到自适应。增加正常直线矢状运动的感知曲率导致实际手部运动曲率的显著（P<0.001）矫正适应;手部运动变得弯曲，从而减少视觉感知曲率。增加正常弯曲的横向运动的曲率产生了显著的（P<0.01）矫正适应;手的运动变得更直，从而再次减少视觉感知的曲率。当自然弯曲的横向运动的曲率减小时，没有显著的适应性（P>0.05）。曲率增加的研究结果表明，轨迹规划在视觉上基于运动学坐标。曲率减小研究的结果表明，期望的轨迹在视觉空间中是直的。这些结果是不兼容的纯dynamicbased模型，如最小扭矩变化模型。我们认为，空间知觉作为中介的视觉轨迹规划中起着至关重要的作用。
There are several invariant features of pointto-point human arm movements: trajectories tend to be straight, smooth, and have bell-shaped velocity profiles. One approach to accounting for these data is via optimization theory; a movement is specified implicitly as the optimum of a cost function, e.g., integrated jerk or torque change. Optimization models of trajectory planning, as well as models not phrased in the optimization framework, generally fall into two main groups-those specified in kinematic coordinates and those specified in dynamic coordinates. To distinguish between these two possibilities we have studied the effects of artificial visual feedback on planar two-joint arm movements. During self-paced point-to-point arm movements the visual feedback of hand position was altered so as to increase the perceived curvature of the movement. The perturbation was zero at both ends of the movement and reached a maximum at the midpoint of the movement. Cost functions specified by hand coordinate kinematics predict adaptation to increased curvature so as to reduce the visual curvature, while dynamically specified cost functions predict no adaptation in the underlying trajectory planner, provided the final goal of the movement can still be achieved. We also studied the effects of reducing the perceived curvature in transverse movements, which are normally slightly curved. Adaptation should be seen in this condition only if the desired trajectory is both specified in kinematic coordinates and actually curved. Increasing the perceived curvature of normally straight sagittal movements led to significant (P<0.001) corrective adaptation in the curvature of the actual hand movement; the hand movement became curved, thereby reducing the visually perceived curvature. Increasing the curvature of the normally curved transverse movements produced a significant (P<0.01) corrective adaptation; the hand movement became straighter, thereby again reducing the visually perceived curvature. When the curvature of naturally curved transverse movements was reduced, there was no significant adaptation (P>0.05). The results of the curvature-increasing study suggest that trajectories are planned in visually based kinematic coordinates. The results of the curvature-reducing study suggest that the desired trajectory is straight in visual space. These results are incompatible with purely dynamicbased models such as the minimum torque change model. We suggest that spatial perception-as mediated by vision-plays a fundamental role in trajectory planning.
影响因子：
14.5
作者：
ABEND, W;BIZZI, E;MORASSO, P
通讯作者：
MORASSO, P