A smart microwave therapy instrument and control system design (1)

Summary: this article primarily describes microwave therapy instrument in the design of intelligent systems.

Briefly describes the composition of the microwave therapy instrument and its features, and a detailed description of the microwave therapy instrument intelligent automatic control system hardware and software design content while on the microwave therapy instrument of some components are introduced. By PID and segmented fitting on microwave therapy instrument of intelligent control, making this microwave therapy instrument work running better than no exploit this control programmes more stable and reliable, the test results have shown that the design is feasible. At the same time developed a PC software for the referral, and treatment of statistical analysis provides a platform.

1 Introduction

Microwave therapy is clinically a new treatment, its equipment is simple, the treatment effect is clear, the use of safe, less complications, tissue damage, so be sure of the medical profession.

Microwave therapy instrument is the use of microwave in the human body produces heat on patients to radiation of lesion, so as to achieve therapeutic purposes, in view of its significant treatment effect, is the development of non-injury treatment of ideal medical equipment. Currently, the hospital using microwave therapy instrument for the majority of imports, the prevalence of bulky, expensive, complex, and so on shortcomings, while domestic production of microwave therapy instrument technology also need to update, the output power of poor stability, resulting in treatment effect is not obvious that the lack of the necessary protective measures, which makes the whole system of security is not very good, intelligent degree not ideal, it is not easy. So there is a need to redesign it, especially in the security and control systems to use the new design methods, in order to achieve the best results.

This article describes the design of intelligent microwave therapy instrument has the following characteristics: (1) control system on the hardware used overload protection, software uses a PID control with segmented fitting methods, the safety of the treatment instrument performance and output power with a radical change; (2) in the software design with embedded operating systems, so that the whole microwave treatment system interoperability, security, performance and stability have reached a new height.

2 mechanism of microwave treatment

Microwave frequency of 300 ~ 300000MHz wavelength 1mm ~ width UHF radio wave, belong to non-ionizing radiation.

Microwave technology in medical diagnosis and treatment of two aspects play an important role.

In microwave treatment process, based on the use of microwave power density in different and distinguish heat treatment and non-thermal effects of the treatment.

At present, thermal treatment mechanism more clearly. The treatment is: most of the human body is composed of water and protein, and other polar molecules, in microwave electric torque, polar molecule along the direction of microwave electric ordered arrangement of movement, and with the high-frequency electric field of alternating back and forth, but in the process of rotation and the adjacent molecules have similar friction collision and generate heat. Make the exposed parts of body tissue temperature increases, blood vessels, and expansion of micro to speed up the metabolism process, improve nutrition and enhance local tissue repair and regeneration capacity. And other thermotherapy, microwave heating of heat conduction from the outside, but by the tissue itself, this heat of high efficiency, good thermal stability of equilibrium [4-6].

3 system composition and theory diagram

The use of microwave-induced thermal treatment principle, the organisms placed microwave radiation field finishes the treatment process.

Instruments, mainly by switches-voltage source, magnetron, linear power supplies, bird, microwave sensors, transducers and micro-controller, etc. PWM switch high-voltage power to produce the required pressure of magnetron, through to high-voltage direct current feedback control, to stabilize the magnetron output power, linear power supply provides a stable DC voltage supply to a filament. Magnetron used medical private magnetron, waveguide (microwave cable) is used to transmit microwave, microwave probe into patients to treatment inside the tissues [5]. Sensor for monitoring the output power of magnetron. Micro-controller for the whole system up and running.

Through a full-bridge rectifier and a comparator, the alternating current into a series of rectangular wave, square wave of falling edge-namely alternating zero-crossing, you will receive an interrupt request, that can trigger the SCR and relays, right trigger point is determined by the system control to achieve the required power.

Power output sensor acquisition magnetrons for monitoring output value, form a closed-loop control systems [3]. At the same time the sensor output is also linked to hardware protection circuit, if control system fails, the output is not controlled, could cause the output power is beyond the scope of the instrument required, at this point, the hardware protection circuit detects output exceeded the signal, the output is forced off to enhance system reliability. After the end of the treatment, the PC software to output information about the current treatment, and saved to the database, for visits to the use and treatment of statistical analysis.

Microwave therapy instrument system block diagram shown in Figure 1.

Figure 1 microwave therapy instrument system block diagram

4 control system

Control system is the core of the entire treatment instrument, all the control directives are issued by it, the control system design is the stability of the entire design of the key.

In order to enhance the equipment reliability and immunity, the use of specialized hardware protection circuit, when a hardware failure, microwave output is not controlled, its power exceeding the set value, the hardware protection circuit will be triggered, auto switching output, improve the overall security of microwave treatment instrument.

In software design, embedded operating system used, so that the whole system stability and immunity has been enhanced. In order to improve the control of the reliability and fast response performance, use the PID closed-loop control, while the output power microwave tubes are voltage, temperature and work time, and other aspects of its output with nonlinear, delay, time-varying characteristics, so will the sensor input intoLine segment-fitting, and in paragraphs setting a different correction factor to make output more stable [1] [2].

4.1 control system hardware design

Hardware key is divided into the following sections.

Power supply for control system provide the power supply; keyboard and LCD display circuit complete man-machine conversation function; the control circuit of magnetron based program directives achieve patient treatment of different diseases; hardware protection circuit to control system failures provide reliable protection; power sensor and AD converters on microwave tube monitor output; output driver from relay and SCR also completed; communications circuit complete controller and PC information exchange; buzzer driver circuit combined with light-emitting diode common treatment for preheating end, end and failure alarm.

Hardware diagram as shown in Figure 2:

Figure 2 hardware diagram