![]() ![]() If suddenly the torque value drops by 10, this is where D is listening and can respond. P will be steady state, and I will be zero. So if the torque system is asking for 100 and getting 100 - happy system. And this one is generally the razors edge. So it needs to be used judiciously.ĭ = Derivative. The issue with I is that it will keep adding, and create overshoot and have to unwind itself after, one cycle at a time. It stops adding output when there is no error. If that added output closes the gap, but there is still error, the "I" term will add more output again. So in the system above, if there is 10 units of error, and that error is present for 1 second, then the "I" term will apply more output to close that gap. Yes, a calculus term, but the basics are that it is a gain term that applies output over time. The "I" comes in for the "if ever" scenario. Not enough "P", and it has sluggish response and takes forever to reach the setpoint, if ever. But it can be quite unstable if you have too much gain, and it'll oscillate - or shake like a dog shitting razor blades, as my old friend used to say. This will create a response proportional to the error - hence the name. So if P is 1, then the output would apply 10 units of torque. The P term multiplies that error (10 units) by the P gain setting to drive the motor that amount. If you are supposed to have 100 units of torque and you are only measuring 90, then you are 10 units away. The PID part effects how much of an output based on how far away you are from the input. I'll try to offer a simple explanation of PID, just for shits and giggles.īasic version on an e-bike PID: it takes an input (torque sensor) and compares it to a setpoint (the amount of torque you are putting in times the assist setting you are in) and drives an output (motor torque) to have the input match the setpoint. It is on-off control, so not a PID, but that is a control loop in your house. Your thermostat is the best and most simple example. It's quite intuitive if you are used to various feedback loops in your life. PID isn't nearly as exotic as it might seem. ![]() In other ways I've felt right at home on the new Altitude PP. It's early days however and an adjustment period is to be expected. The reach is on the long side for me and I may be able to address that with the Ride-4 system, but I have thus far left the chainstays in the shorter setting. I'm hoping I can make it feel a little more poppy with some tuning refinements (both the shock and the Ride 4 adjustment) but thus far it isn't as playful as I'd like, even for a ~53 lb 24 kg (size XL) eMTB.Īfter four rides (3 if them at Megavolt) I have found the Altitude PP most at home at speed and in rough and rocky situations and a little less competent in tighter terrain. The counter point to this stuck to the ground feeling is that it is indeed a little earthbound when it comes time to get off the earth. It also deals with large hits effectively and tracks very well, both in corners and when things get lumpy. The rear wheel tracks very well, perhaps because of the mid–high main pivot and the more rearward axle path. The first thing I noticed both up and down with the new Altitude PP, was improved traction. ![]()
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