Determining camshaft deceleration rate from Follower?

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Discussion Overview

The discussion revolves around the physics of camshaft deceleration rates in relation to a motor acting as a follower. Participants explore the relationship between the camshaft's speed and the torque characteristics of the motor, particularly in the context of maintaining optimal performance without exceeding certain torque limits.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant describes a scenario where a camshaft moves at a constant speed while the follower motor's torque decreases at higher speeds, raising questions about the deceleration formula needed to keep the motor within a specific torque limit.
  • Another participant draws a parallel to regenerative braking in modern cars, suggesting that the deceleration rate should vary based on speed to optimize torque usage.
  • A participant questions the system's description, expressing confusion about how a motor can function as a cam follower and requests a sketch for clarification.
  • There is a suggestion that torque limitations at high speeds may be due to maximum power constraints, though uncertainty remains regarding whether this limitation is imposed by the motor or the battery.
  • One participant expresses doubt about the necessity for torque to follow the same curve during regenerative braking as it does under power conditions.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus, as there are multiple competing views regarding the mechanics of the system and the implications of torque behavior under different conditions.

Contextual Notes

There are limitations in the system description, including unclear definitions of the roles of the camshaft and motor, as well as unresolved questions about the relationship between torque and speed in the context of regenerative braking.

AmazingTrans
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I am doing this as a hobby, trying to understanding some physics calculation for camshafts and following cam s,v,a,j.
All pictures in this thread are just samples that tie to nothing much, other than just images.

p34.png

7y94hR.png


1. From the 1st image above, the camshaft (emulated digital signal) is moving at a "constant speed", and the follower (motor) has the following plot. The camshaft has no boundaries in terms of velocity, acceleration, or jerk since it is digitally emulated.

I also have included the follower (which is a motor) properties. (Yes that's a tesla S motor. =D ) As we can see, the higher the speed of the motor, the lesser torque.

If the follower/motor is running at 120 mph and only capable of "d Nm" (reduced torque),
At point #2 of the cam plot and the camshaft decided to stop at a specific rate "x".
What would the camshaft deceleration formula look like if I want the follower/motor to not exceed 75% of the torque curve at that point ?

My goal here is to use to constantly change the camshaft deceleration rate such that the follower does not ride along its torque curve all the time.
 
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I just thought, another good example of this application would be like today car (Nissan) where they use regenerative braking to brake the car.
If they were to run the car at higher speed, they have limited torque at that point. I would think the controller would constantly change its deceleration rate such that the motor follows the torque curve of the motor until it reaches low speed, then it will apply higher deceleration rate (more torque) when it is at lower speed.
 
There seems to be something missing in your system description. How can a motor be a cam follower? I've done a lot of work with cams, but I've never seen anything that I would describe like this. Could you give us a sketch of the system you are talking about, please?
 
AmazingTrans said:
I just thought, another good example of this application would be like today car (Nissan) where they use regenerative braking to brake the car.
If they were to run the car at higher speed, they have limited torque at that point. I would think the controller would constantly change its deceleration rate such that the motor follows the torque curve of the motor until it reaches low speed, then it will apply higher deceleration rate (more torque) when it is at lower speed.

Torque at high speed is probably limited because max power has been reached. I'm not sure if max power is limited by the motor or battery on the Tesla.

I can't think of a reason why, under regenerative braking, the torque should be limited to exactly same curve as under power.
 

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