利用平衡电桥绘制二次曲线

Drawing the Conics by Use of Balanced Bridge

圆锥曲线是二次曲线中最常用的一种，也是工程设计中最常用的。圆和椭圆的绘图仪器已有产品，但还没有一种绘图仪器可以绘制全部圆锥曲线（圆、椭圆、抛物线和双曲线）。本文介绍的仪器利用自动平衡电桥的工作原理，采用微电机驱动，能够自动完成圆、椭圆、抛物线和双曲线的绘制。

The conic is one of conics most in use,and it is used for the engineering design frequently. The instrument which are used for drawing the circle and ellipse are available,but there is no yet the instrument used for drawing all the conics including circle,ellipse,parabola and hyperbola.The paper introduces the instrument which applies the operating principle of balance bridge,is driven by the micro-motor and can automatically draw the circle, ellipse,parabola and hyperbola.