功率超声设备振幅模糊控制技术的研究

Study of the fuzzy control technique for the amplitude of the power ultrasonic instrument

利用功率超声医疗设备对病人进行治疗的过程中 ,手术刀的振幅是一个关键的控制参数 ,它直接影响到手术的效果。由于手术刀的振幅随着环境的温度、时变非线性的负载、以及加压等因素的影响而变化 ,故此需要对振动系统的振幅进行稳定控制。首先分析了纵向复合棒大功率换能器加接刀具的振动系统的等效机电模型 ,根据等效机电模型提出了一种基于自调整PID模糊控制器的功率超声设备振幅控制方法。并分析了自调整PID模糊控制器的结构和原理 ,这种控制器同PID控制器相比较 ,既可以消除极限环振荡 ,又可以消除系统余差的优点。最后给出了一种实用的方法。实验表明采用该模糊控制技术提高了系统的鲁棒性和控制精度 。

The effect of operation is directly determined by the vibration amplitude of the ultrasonic scalper, which is a key control parameter on the treatment for the patient by using the power ultrasonic medical instrument.Because the vibration amplitude of the scalper changes with multiple factors such as environmental temperature, time variance nonlinear load and static state press, a vibration amplitude control technique is needed for obtaining the stable vibration amplitude in the power ultrasonic medical system. This paper analyzes the equivalent electromechanical model of the ultrasonic vibration system made up of a longitudinal composite bar high_power transducer, a horn and a scalper, and presents the vibration amplitude control approach based on the self_modifying PID fuzzy controller for the power ultrasonic medical instrument.Compared with the PID controller,the self_modifying PID fuzzy controller has two merits: avoidance of the limit circle oscillation and elimination of the system residual error.Finally,it states the design procedure.The experiments show that the robustness and the control accuracy of the power ultrasonic system can be improved by using the self_modifying PID fazzy control technique.