Smith J P, Barsotti R J
Bockus Research Institute, Graduate Hospital, Philadelphia, Pennsylvania 19146.
Am J Physiol. 1993 Nov;265(5 Pt 1):C1424-32. doi: 10.1152/ajpcell.1993.265.5.C1424.
We have developed a computer-based servo system for controlling isotonic releases in muscle. This system is a composite of commercially available devices: an IBM personal computer, an analog-to-digital (A/D) board, an Akers AE801 force transducer, and a Cambridge Technology motor. The servo loop controlling the force clamp is generated by computer via the A/D board, using a program written in QuickBASIC 4.5. Results are shown that illustrate the ability of the system to clamp the force generated by either skinned cardiac trabeculae or single rabbit psoas fibers down to the resolution of the force transducer within 4 ms. This rate is independent of the level of activation of the tissue and the size of the load imposed during the release. The key to the effectiveness of the system consists of two algorithms that are described in detail. The first is used to calculate the error signal to hold force to the desired level. The second algorithm is used to calculate the appropriate gain of the servo for a particular fiber and the size of the desired load to be imposed. The results show that the described computer-based method for controlling isotonic releases in muscle represents a good compromise between simplicity and performance and is an alternative to the custom-built digital/analog servo devices currently being used in studies of muscle mechanics.
我们开发了一种基于计算机的伺服系统，用于控制肌肉中的等张释放。该系统由市售设备组成：一台IBM个人计算机、一块模拟数字（A/D）板、一个Akers AE801力传感器和一个剑桥科技公司的电机。控制力钳位的伺服回路由计算机通过A/D板生成，使用QuickBASIC 4.5编写的程序。结果表明，该系统能够在4毫秒内将皮肤心肌小梁或单根兔腰大肌纤维产生的力钳位到力传感器的分辨率。这个速率与组织的激活水平和释放过程中施加的负载大小无关。该系统有效性的关键在于详细描述的两种算法。第一种用于计算误差信号，以将力保持在所需水平。第二种算法用于计算特定纤维的伺服适当增益以及要施加的所需负载大小。结果表明，所描述的基于计算机的控制肌肉等张释放的方法在简单性和性能之间取得了良好的平衡，是目前肌肉力学研究中使用的定制数字/模拟伺服设备的一种替代方案。
