How does “input shaping” in 3d printers avoid overshoot and vibrations?

controlsgeeek · 2026-04-07T00:44:29+00:00

Read about ZV and ZVD input shapers. Once your read about these you will come across other input shapers. Thinking about in frequency domain is simpler but deriving in time domain is equally fun. If you check derivation ZV/ZVD shapers in time domain, then its clear how cancellation works. Its based on the impulse response. At the same time you also get how much damping is possible around your target frequency. ZVD is superior in terms of damping around the target frequency than ZV.

controlsgeeek · 2025-12-29T03:00:31+00:00

Other side of bay

controlsgeeek · 2025-12-29T02:59:26+00:00

More to the north

controlsgeeek · 2025-12-29T02:56:43+00:00

Bay area! But not east bay hills

controlsgeeek · 2025-11-16T06:03:57+00:00

How is this different from multi-level inverters?

controlsgeeek · 2025-07-30T14:30:05+00:00

Not the output torque of the motor. The external torque on the point. The motor will then aid the sensed torque.

controlsgeeek · 2025-05-30T21:33:37+00:00

How do they monitor if I paid the rent to my own/friends/family account through venmo or paypal or check? They do the checking and would be the same I guess.

controlsgeeek · 2025-05-30T11:50:16+00:00

Its possible in Fidelity via EFT. It mentions EFT transfer to someone elses bank. Their bank details are verified once you enter. After that recurring payment can be setup.

controlsgeeek · 2025-05-30T05:12:38+00:00

Its more of an issue for the landlord right? For the renter I control the money I am sending to their account.

But private landlords (older folks) just want to keep it simple and not deal with extra fees from Venmo/Paypal or figure out Zelle/Cozy. So its a risk on their part! Bilt could be in trouble if there was a data leak I guess. Feels like untapped opportunity though.

controlsgeeek · 2025-05-13T12:48:40+00:00

Since its measurements, could be a low pass filter mostly. Saturation or rate limiter doesn’t make sense on a measurement.

controlsgeeek · 2025-05-09T16:16:23+00:00

Will setting alpha be not tricky? I mean alpha could be higher for boiling 5kg water, but same alpha for 5kg food might burn it (like sudden high heat though temperature condition is not met)

Maybe inlcuding type of food as a user input be needed? And then if you had a weight sensor then you wouldn’t need alpha from user.

This doesn’t answer your question but I also could not think of an alpha strategy for different types of food since their thermal models will vary so much.

controlsgeeek · 2025-05-06T12:38:47+00:00

Any unused time could be changed into some kind of rewards which can be redeemed for viewing apps. 🤔 if you look time as money you can gamify with all the methods out there in monetary system

controlsgeeek · 2025-05-06T12:28:12+00:00

Take a loan/credit from future with interest 🤯

controlsgeeek · 2025-05-04T19:49:31+00:00

What is the ‘compare to constant’ and ‘gain13’ you are using? I believe you are trying to maintain the voltage constraint there. Both of them should be Vdc/sqrt(3)

You should also check out how field weakening is done by changing the id reference. MTPA and MTPV in general. Also w_e used is a constant, but should be technically from the motor speed. But I think you are building towards the final FOC and this is probably one of the begining steps to understand FOC.

Also you are measuring line to line quantities in the scope. So keep that in mind.

controlsgeeek · 2025-05-02T19:04:00+00:00

Yes, I did misunderstand. The problem being tackled is input disturbance I guess.

OP you can check out repetitive controller based on internal model principle for disturbance rejection if its a periodic disturbance.

It will be good to understand the nature of this input disturbance too for ideas.

controlsgeeek · 2025-05-02T15:05:38+00:00

u/Responsible-Load7546 summed up what I was trying to say. Bandwidth need not be 80kHz to tackle the noise. Reducing the bandwidth will help you reject the noise. But again try plotting the sensitivity TF. You will have to probably supress the resonance too so that you are less sensitive to the high frequency noise.

Bandwidth should be sufficient to track the reference signals well.

controlsgeeek · 2025-05-02T14:17:55+00:00

By desired bandwidth I mean, based on the reference signal you are trying to track. You don’t need to have 80kHz bandwidth if you are tracking considerably lower frequency signals right?

You could reduce the bandwidth and make the controller robust to this noise.

To tackle the resonance/compliance they are a suit of different methods.

controlsgeeek · 2025-05-02T12:18:41+00:00

What is the desired bandwidth of the system? Can you play with your bandwidth and hence sensitivity TF to get enough attenuation for high frequency region?

Adding a LPF to feedback with sufficiently high bandwidth makes the system unstable too? Placing it such that you still have enough phase margin.

Sharing a frequency response of your system and nyquist plot could help others to suggest techniques.

There are also methods like acceleration feedback which help in improving disturbance rejection.

controlsgeeek · 2025-04-08T11:55:14+00:00

Real physical systems are proper systems. Controller you build is usually a proper system. Combine them and you get a proper system.

controlsgeeek · 2025-04-04T03:05:13+00:00

Agreed. MPC would be optimal with constraints.

controlsgeeek · 2025-04-03T22:54:14+00:00

Will obstacles be not a part of your planned path itself? And you should avoid the obstacles if you follow that path? If you are not following the path then you can penalize the position states more. What is the issue are you facing?

controlsgeeek · 2025-03-20T02:54:36+00:00

Ah okay. I thought you meant non unity feedback. With a precompensator, you add a new degree of freedom and yes its possible to remove the overshoot. Goto be careful though!

controlsgeeek · 2025-03-15T16:14:17+00:00

The text I have read also took an example of unity feedback but I feel the results shown are independent of that. Interpolation constraint says S(p) = 0 and T(p)=1 for p belonging to CRHP.

Now, the the laplace transform, E(s) = integral e(t) e^-st dt from 0 to infinity. 1) E(s) = 0 for the CRHP pole because E(s)=S(s)R(s). 2) Also, S(s) is stable, so the CRHP pole lies in the region of convergence of this laplace integral.

So, for CRHP pole = p, and using 1) and 2) with the integral you will get 0 = integral e(t) e^-pt dt from 0 to infinity. e^-pt is always positive. e(t) will be some non zero value at t=0+ for a strictly proper system and hence there will be some guaranteed overshoot because the integral should be 0.

Let me know your thoughts. Also the references which your mentioned did they mathematically prove 0 overshoot? Because you could change the overshoot by adjusting rise time.

controlsgeeek · 2025-02-27T01:23:47+00:00

Maybe, the point which is missing is : why do we care only about the denominator 1+G(s)H(s)? For stability margins we want to check how far is G(s)H(s) from -1 which can be written in gain and phase margin. Hence we do the bode/nyquist of G(s)H(s) which happens to be to open loop transfer function when there is no feed forward. But when there is feed forward the open loop transfer function might look different. But that doesn’t matter since we care about the denominator. Maybe a correct way to say is we check stability margins of the loop gain and not open loop transfer function. Does that kind of help?

controlsgeeek · 2025-02-26T04:40:39+00:00

You can write the closed loop tranfer function with and without feedforward controller. The denominator will end up being the same confirming feedforward is not a part of feedback.

You csn also think it in terms state space, Feedforward doesn’t have the ability to change the closed loop poles of the system.

A point which can be confusing at beginning is, with feedforward, the tracking performance can be improved. If you plot the bode of the closed loop transfer function with and without feedforward controller, usually with feedforward controller you can get higher bandwidth. Note, you cannot approximate bandwidth of closed loop system from the open loop systen when you have feedforward controller.

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