INNOVATEST轶诺致力于设计和制造传感器闭环控制加载的硬度计。为了更好地理解闭环系统相对于砝码式系统的优越性，我们必须弄清楚两种系统的区别所在。

在工业化初期，测量机械结构的试验力至关重要。大约在1940年，一种应变式称重传感器被发明出来。用于测量试验力并将该力值以电信号形式输出的力传感器，大部分使用应变片来将材料变形/力转换成电信号。

19世纪50年代，力传感器应用于拉伸和压缩试验机。力传感器理想的安装位置，是在与工件的连接处的前端或尽量靠近的区域。电子系统利用反馈信号来调节加载装置，进而得到设定的试验力。

基于闭环系统的优越性能，如今，所有电子拉伸压缩试验机都只采用闭环控制。闭环系统可以连续测量加载试验力，且闭环系统中使用的组件比砝码式要简单得多。正如上文提到的砝码式系统，为确保运行正常，砝码式系统要求杠杆、轴点和零部件间的摩擦（相互配合）。

对于一台硬度计，压头是测试系统与样品接触的一部分，它是获得正确硬度值最重要的一个因素。为了消除结构缺陷的影响，机械方面的移动或其他干扰都会影响试验力，因此力传感器需与压头尽可能靠近。

只有这样，基于力传感器的优势，闭环系统才能获得较高的试验力精度。如将力传感器安装在硬度计其他位置，它相对于传统砝码式系统的优势将不复存在。

作为机器的核心，INNOVATEST工程师已设计出独特的非商业的力传感器和反馈系统。几乎所有的INNOVATEST硬度计的压头都安装在适合试验力测试的位置，并保证了闭环技术的优势。

闭环系统的优势：高精度试验力力反馈系统确保加载试验力的准确性宽泛的试验力且不受限于机械结构简便的测试流程对比砝码系统，简化机械结构简单的校正程序

闭环系统的缺点:对比砝码系统，价格更贵需要供电系统

INNOVATEST designs and manufactures, primarily, load cell based, closed loop hardness testing machines. To understand the great advantages of the closed loop systems over dead weight systems, particularly in hardness testers, one should understand the difference between both systems.

Measuring force in mechanical constructions became important in the early days of industrialization. Around 1940, a Strain gauge load cell was invented. A load cell is a transducer (sensor) that measures force, and outputs this force as an electrical signal. Most load cells use a strain gauge to turn material deformation/force in to an electric signal.

During the 1950s, load cells where implemented in tensile & compression testing machines. The load cell would most ideally be mounted just before or as close as possible to the contact point with the workpiece. The electronic system is designed to use the feedback to adjust the force application mechanism (motor) to apply only the desired force. Closed-loop systems work so well that today all electronic tensile/compression instruments exclusively use closed-loop control.A closed-loop system can constantly measure the test force being applied, and also the components used in a closed-loop system inherently lend themselves to a much simpler design than a dead-weight system. As mentioned on the DEAD WEIGHT systems page, dead-weight systems require levers, pivots and other friction-inducing components to function efficiently.

In a hardness tester, the indenter, the only part of the force system in contact with the test sample is the most important element for a correct hardness measurement. To eliminate the effect of mechanical imperfection, mechanical moving or other disturbance that could affect the test force, the load cell should be installed as close as possible to the indenter.

Only in this way the real advantage of load cell based, closed loop systems come to their maximum force accuracy. Load cells placed on other positions in the hardness testers mechanical force actuator, rapidly lose most of their advantage over traditional dead weight systems.

INNOVATEST engineers have designed unique non-commercial load cells and force application systems that are the heart of each machine. Nearly all INNOVATEST hardness testers measure force at the indenter mount location to assure the maximum benefits of closed loop technology.

Advantages of closed loop system:High accurate test forcesForce feedback assures correct force is appliedWide range of test forces not depending on mechanical limitationsFaster test proceduresReduction of mechanical parts comparing to dead weight systemsSimple electronic calibration procedure

Disadvantages of a closed loop system:More expensive than a dead weight systemRequires electricity