上面的朋友提问得很好，因为同步都是谈相对同步，没有绝对同步，你说的这种情况，两缸的阀口开度有微小误差，如0。1mm一0。2mm。这跟阀口增益和油源压力都有关系。实际上在全行程运行中都在自动调节，如果运行1000mm，这种微小误差用肉眼儿乎看不出来，并且不受油缸直径、内漏大小的影响。油缸数量的影响，所以几乎是多油缸同步的终极解决方法。如果用这个难题求教伺服权威PEN先生，哪更说不清楚了。
蜻蜓 发表于 2017-12-6 07:32
数字液压您好：有一个问题请教，假如用两个数字缸同步控制，两缸用同一油源，如果机构是偏载的，比如一个缸 ...
数字缸内部带有机械式位置闭环，由于负载的不同会导致两个阀口压降不同，因而会在运行中产生微小的同步误差（这个误差与阀口增益、系统压力、负载等都有关系），但只要这个同步误差在我们允许的范围内（我们在给用户提供数字缸时是要计算选型适当的数字缸性能的），我们即可认为两缸同步。这个原理其实与伺服阀控双缸同步原理是相同的，不同的是数字缸内部的机械反馈和调节装置使得我们不需要进行伺服阀各种参数的设定和调整，这个系统成套就简单了。
谢谢解答，数字液压的解答能理解，但杨老的解答没看明白，给两缸输入相同数量和相同频率的脉冲数，这时阀开口量不是应该相同的吗？怎么会出现0.1-0.2MM 的差别？还有这句“实际上在全行程运行中都在自动调节”也没明白。如果没有外置传感器检测和反馈如何自动进行误差检测和调节？
蜻蜓 发表于 2017-12-6 21:08
谢谢解答，数字液压的解答能理解，但杨老的解答没看明白，给两缸输入相同数量和相同频率的脉冲数，这时阀开 ...
他是机械反馈，相当于半闭环
伺服液压怎样实现精确的速度控制和位置?这个问题真不好回答吗？如果真难，简单回答也可以啊！
求高手了。
因为我没有搞过伺服液压，如果我干过，我就不会问这个问题了。
请问，哪里可以搞到机械液压伺服控制液压缸图纸等资料
越详细越好，实在不行简单的也行，求连接
alexzc231 发表于 2017-12-1 05:21
In my view, every equation in engineering have its limitation, to discus which equation is most accu ...
Are your saying ignore simulations because they aren't perfect?
The equations don't need to be exact.They only need to be close.
If equations were perfect there would be no need for closed loop control.If the equations can match to actual system closely then feed forward control can be very close to perfect and closed loop control can reduce error even more.
E, the bulk modulus of oil, does not change that much in an operating system.When modeling assume a low value for E.
The uncertainty of the mechanical components is often as high as 10%. When modeling I can use worst case values to see if the simulation still works.
I can solve many non-linear differential equations at the same time.I can make the bulk modulus of oil a function of pressure and temperature.However, for normal hydraulic system the bulk modulus of oil does not vary much.
alexzc231 发表于 2017-12-1 05:21
In my view, every equation in engineering have its limitation, to discus which equation is most accu ...
Are your saying ignore simulations because they aren't perfect?
The equations don't need to be exact.They only need to be close.
If equations were perfect there would be no need for closed loop control.If the equations can match to actual system closely then feed forward control can be very close to perfect and closed loop control can reduce error even more.
E, the bulk modulus of oil, does not change that much in an operating system.When modeling assume a low value for E.
The uncertainty of the mechanical components is often as high as 10%. When modeling I can use worst case values to see if the simulation still works.
I can solve many non-linear differential equations at the same time.I can make the bulk modulus of oil a function of pressure and temperature.However, for normal hydraulic system the bulk modulus of oil does not vary much.
alexzc231发表于2017-12-1 05:21
在我看来，在工程的每一个方程有其限度，讨论方程是最准确的…
你的话是不是忽略了模拟，因为它们并不完美？
方程不需要精确。他们只需要靠近。
如果方程是完美的，就不需要闭环控制。如果方程能与实际系统紧密匹配，则前馈控制可以非常接近完美，闭环控制甚至可以减少误差。
在操作系统中，油的体积模量不会改变那么多。当建模假定E值较低时。
机械零件的不确定度通常高达10%。当建模时，我可以使用最坏的值来判断模拟是否仍然有效。
我可以同时解决许多非线性微分方程。我能使油的体积模量随压力和温度的变化而变化。然而，对于普通液压系统，油的体积模量变化不大。
尊敬的Mr Peter，我和您讨论过相关的方案，最近事情比较多，而且最近也懒得关注懒得发言，没想到您还在认真的陪一些人聊天。
我建议您系统的总结您的观点，由Change Tongli 和我来负责解释您的观点。
您单独可以发帖讨论，不要和别人搅和
无论什么结构多么伟大，目前还逃不出已经有的控制理论
我相信您，也支持professor Change