第十一章液压位置伺服系统 Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 一、工作原理 1、伺服阀 2、油缸 3、工作台 4、位移传感器(滑动变阻器) 电液伺服系统中,位置系统是最常见的。其优点是: 2、具有高精度和快速响应能力,具有很好的灵活 性和适应能力。 1、能控制很大的惯量和产生很大的力和力矩; 第一节位置控制系统 Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 液压速度控制系统??D sp 0p 工作台 F 伺服、放大、校正装置伺服阀测速电机 u? furu ?指令电位器? i Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. ?系统固有部分由比例、积分、二阶振荡环节组成 22 ( )2 ( 1) vh h h K G s s s s ?? ??? ? Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 二、稳定性分析在 h?处出现一个峰值,其对数幅值为 20lg( ) 2 v h h K ??稳定性判据: 20lg( ) 0 2 v h h K ???即: 12 v h h K ???2 v h h K ??? Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 由于 c V K??,故稳定条件也限制了系统的穿越频率 c?,即限制了系统的频宽。通常液压阻尼比 ~ h??,故稳定性条件可写成: ( ~ ) v h K??可见 VK被限制在 h?的 20%~40% 之间,因此, 对未经校正的系统要使频宽大于 h?是很难达到的。为改善系统的性能,采用提高 h?的措施,也采用 Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyrig
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