Development of a Testing Apparatus for Injury of the Knee Ligament Using Robotics. -Application of three Dimensional Displacement Transducer-

我们开发了一种新的测量膝关节不稳定的仪器方法。测试装置由测试肢体的定位支架和关节机器人组成。将通用力矩传感器系统（UFS系统）安装在机器人的手腕上。UFS系统不仅可用于精确测量施加在小腿上的力，而且可用于定位测试膝关节在中性位置。采用线性可变位移传感器（LVDT）测量前后位移。一个传感器垫与髌骨接触，另一个传感器垫固定在小腿支撑处。通过机器人对小腿施加60 N （6 kgf）和80 N （8 kgf）的前后力。试验均在膝关节屈曲20 ~ 30度时进行。本仪器的特点是能直接、灵敏地检测出试验韧带的刚度。我们用力-位移曲线末端区域的斜率（末端刚度指数）来表示韧带的刚度。前终端正常膝盖的刚度指标的均值为28500 N / m的力量60 N和28500 N / m在80 N的力的均值后终端刚度指标正常的膝盖是33600 N / m的力量60 N和40900 N / m在80 N . O) N的力另一方面,膝盖的前末端刚度指标与前交叉韧带破裂从5600年到9300年在部队60 N和N / m 80 N。

We have developed a new method of instrumented measurement for knee instability. The testing apparatus consisted of positioning supports for test limb and an articulated robot. The universal force moment sensor system (UFS system) was attached to the wrist of robot. The UFS system was not only useful for measuring precisely the force applied to lower leg but for positioning test knee in neutral position. The anterior-posterior displacement was measured with linear variable displacement transducer (LVDT). One sensor pad was placed in contact with the patella and the other pad was fixed to the support of lower leg. Anterior and posterior force of 60 N (6 kgf) and 80 N (8 kgf) were applied to lower leg through the robot. The test were performed 20 to 30 degrees of knee flexion. The characteristic feature of our apparatus was that it could detect directly and very sensitively the stiffness of test ligament. We represented the stiffness of ligament by the slope of terminal region of force-displacement curve (terminal stiffness index). The mean of anterior terminal stiffness indexes of normal knees was 28,500 N/m at a force of 60N and 28,500 N/m at a force of 80 N. The mean of posterior terminal stiffness indexes of normal knees was 33,600 N/m at a force of 60 N and 40,900 N/m at a force of 80 N. O) n the other hand, the anterior terminal stiffness indexes of the knee with rupture of anterior cruciate ligament were ranging from 5,600 to 9,300 N/m at forces of 60 N and 80 N.