Parameter identification of inertially stabilized platforms using current command design

Accurate parameter identification is essential when designing controllers for inertially stabilized platforms (ISPs). But traditional identification methods suffer from observation measurement noise and operating restrictions of ISPs. To address this issue, a novel identification method based on current command design and multilevel coordinate search (MCS) algorithm without any higher order measurement differentiations was proposed. The designed current commands were adopted to obtain parameter decoupled models with the platform operating under allowable conditions. MCS algorithm was employed to estimate the parameters based on parameter decoupled models. A comparison experiment between the proposed method and non-linear least square method was carried out and most of the relative errors of identified parameters obtained by the proposed method were below 10%. Simulation and experiment based on identified parameters were conducted. A velocity control structure was also developed with disturbance observer (DOB) for application in disturbance compensation control system of an ISP. Experimental results show that the control scheme based on the identified parameters with DOB has the best disturbance rejection performance. It reduces the peak to peak value (PPV) of velocity error integral to 0.8 mrad which is much smaller than the value (10 mrad) obtained by the single velocity controller without DOB. Compared with the control scheme based on sweep model with DOB compensation, the proposed control scheme improves the PPV of velocity error integral by 1.625 times.     

精密谐波传动系统建模

针对谐波传动系统的控制方法与性能预测问题,本文考虑影响谐波传动系统性能的主要因素,提出了一种精密谐波传动系统建模方法。建立了整个谐波传动系统的动力学模型和Simlink仿真模型,给出了仿真模型中各参数的获取方法。针对模型中难于准确测得的参数,提出了一种最小二乘辨识方法。对谐波传动系统的仿真模型进行了时频域仿真分析与实验验证,结果表明:建立的谐波传动系统模型各参数具有明确物理意义,便于工程应用;建模时仅利用一次扫频即可得到所有未知参数的估计值,提高了参数获取的效率,降低了成本;仿真模型与实际系统时频域特性基本一致,所有结果匹配度超过70%。得到的结果验证了该建模方法的正确性。     

摩擦对稳定跟踪平台低速性能影响的研究

以某型直升机驾驶员夜视系统稳定跟踪平台伺服系统设计为背景，针对系统中存在的非线性摩擦影响，着眼于摩擦模型、二质量伺服系统模型以及摩擦补偿问题，从理论上进行了探讨。     

舰载天线稳定平台振动分析与减振设计

振动和冲击直接影响稳定跟踪平台的可靠性和稳定性。在确定振动相关参数基础上，利用虚拟样机技术对减振器进行设计分析，选择了具体型号，在2-60Hz的各个频率段内进行增加减振器后振动频率的仿真分析，取得良好减振效果。     

一种柔顺缓冲摇架及其导向刚度的计算方法

为了研究新型缓冲技术,提出一种新型的柔顺缓冲摇架及其导向刚度计算方法.以自动武器站缓冲系统的柔顺缓冲摇架为例,应用对称变换法将柔顺缓冲摇架简化为竖杆模型和U杆模型,根据各杆之间的串并联关系反求柔顺缓冲摇架的刚度,可以得到一种计算柔顺缓冲摇架导向刚度的理论方法;运用solidworks自带的simulation插件进行静力学仿真分析;并应用锤击法对柔顺缓冲摇架进行实验测试.对比3种方法所求得的柔顺缓冲摇架的刚度值,可证明柔顺缓冲摇架导向刚度的理论计算方法准确可行,对柔顺缓冲机构的设计具有一定的指导意义,并为柔顺缓冲机构在缓冲领域的应用奠定了一定的基础.     

数控测试用伺服进给系统非线性建模与仿真

提出了一种基于虚拟机床的数控系统运动控制性能新型检测方法,介绍了测试系统的结构与工作原理,并充分考虑间隙与摩擦等非线性因素的作用效果,建立了用于数控测试的机床伺服进给系统的非线性综合仿真模型。仿真实验结果表明间隙及摩擦等非线性因素会影响系统控制效果与加工精度,验证了非线性建模在数控系统运动控制性能测试中的必要性。所建模型为虚拟机床的设计奠定了基础,所提出的检测方法为全面测试数控系统运动控制性能提供了新途径。     

狙击步枪新型电动击发装置设计与分析

针对狙击步枪手动击发对瞄准线的扰动以及响应速度慢等不足,提出一种新型嵌入握把内部的电动击发装置,分析其工作原理,建立电击发装置的参数化模型,并对该电击发装置进行了仿真分析与实验测试。结果表明：该电动击发装置能够实现发射机电控击发,其对瞄准线方位方向的扰动幅度降为手动击发的1/5,可有效降低击发对瞄准线的扰动,提高射击精度;响应时间约为35 ms,远快于手动击发速度,提高了狙击步枪击发的响应速度,有助于准确把握击发时机。     

Multi-rate tracking controller analysis and design for target tracking systems

As the sampling rates of the inner loop and the outer loop of the target tracking control system are different, a typical digital multi-rate control system was formed. If the traditional single-rate design method was applied, the low sampling rate loop will seriously impact the dynamical characteristic of the system. After analyzing and calculating the impact law of the low sampling rate loop to the bandwidth and the stability of the tracking system, a kind of multi-rate control system design method was introduced. Corresponding to the different sampling rates of the inner loop and the outer loop, the multi-rate control strategy was constituted by a high sampling rate sub-controller and a low sampling rate sub-controller. The two sub-controllers were designed separately and connected by means of the sampling rate converter. The low sampling rate controller determined the response rapidity of the system, while the high sampling rate controller applied additionally effective control outputs to the system during a sampling interval of the low sampling rate controller. With the introduced high and low sampling rates sub-controllers, the tracking control system can achieve the same performance as a single-rate controller with high sampling rate, yet it works under a much lower sampling rate. The simulation and experimental results show the effectiveness of the introduced multi-rate control design method. It reduces the settling time by 5 times and the over shoot by 4 times compared with the PID control.     

快速反射镜两轴柔性支承设计

提出了基于集中柔度的柔性铰链单元的柔性支承结构,研究了这种柔性支承静动态特性的设计过程和设计方法。首先,从快速反射镜的工作机理出发,分析了系统对柔性支承的特性要求;然后,结合现有两种柔性支承结构的特点,提出基于集中柔度的柔性铰链单元的柔性支承设计;在分析单个柔性铰链刚度特性的基础上,研究了两轴柔性支承的设计方法;最后,以通光口径为Φ90 mm、行程为±2 mrad、工作带宽为300 Hz的两轴快速反射镜为例,进行了两轴柔性支承的设计和特性计算。基于dSPACE半实物仿真系统建立了两轴柔性支承特性实验,对柔性支承的转动刚度进行测试,并对由设计的柔性支承组成的快速反射镜系统的控制性能进行分析。实验结果显示:设计的快速反射镜系统的一阶机械响应频率为78 Hz,闭环控制带宽为340 Hz,满足设计要求,表明基于集中柔度的柔性铰链单元的柔性支承可以满足行程若干mrad,工作带宽数百Hz的两轴快速反射镜的应用需求,且具有加工工艺性好,转动中心稳定等优点。     

Prestiction friction compensation in direct-drive mechatronics systems

LuGre model has been widely used in friction modeling and compensation. However, the new friction regime, named prestiction regime, cannot be accurately characterized by LuGre model in the latest research. With the extensive experimental observations of friction behaviors in the prestiction, some variables were abstracted to depict the rules in the prestiction regime. Based upon the knowledge of friction modeling, a novel friction model including the presliding regime, the gross sliding regime and the prestiction regime was then presented to overcome the shortcomings of the LuGre model. The reason that LuGre model cannot estimate the prestiction friction was analyzed in theory. Feasibility analysis of the proposed model in modeling the prestiction friction was also addressed. A parameter identification method for the proposed model based on multilevel coordinate search algorithm was presented. The proposed friction compensation strategy was composed of a nonlinear friction observer and a feedforward mechanism. The friction observer was designed to estimate the friction force in the presliding and the gross sliding regimes. And the friction force was estimated based on the model in the prestiction regime. The comparative trajectory tracking experiments were conducted on a simulator of inertially stabilization platforms among three control schemes： the single proportional-derivative （PD） control, the PD with LuGre model-based compensation and the PD with compensator based on the presented model. The experimental results reveal that the control scheme based on the proposed model has the best tracking performance. It reduces the peak-to-peak value （PPV） of tracking error to 0.2 mrad, which is improved almost 50% compared with the PD with LuGre model-based compensation. Compared to the single PD control, it reduces the PPV of error by 66.7%.