...really the most efficient speed controller relies on the application. There are a few schemes through which a, specifically brushed DC, motor can be controlled. While one could use a H-bridge in order to switch the current direction through the motor, as given in your link (which I found to be pretty insightful), one could also use a dual supply and a variable voltage supplied to the motor allowing for a full voltage swing from the negative supply to the positive(disregarding losses, of course). Where the PWM method works and is my most used method, due to its simplicity and capability to be driven, however indirectly, by a digital device(Darlignton Pairs, MOSFET drivers, etc.), if positional accuracy is the main requirement, then the dual supply mode is a must.
What does the DaVinci Robot use? http://en.wikipedia.org/wiki/Da_Vinci_Surgical_System Would the jerkiness(as described in your link), however minimal, be acceptable while operating on a human? In this instance where accuracy is required, a dual supply is essential to the efficiency of the robot, so as to not sever a limb or something.
-Tim
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Center-aligned PWM improves brushed DC motor control
An application like the DaVinci robot will not use brushed DC motors. It will use BLDC, and most likely PMSM motors with some form of Field Oriented Control which is in essence Alien Technology. What you get is a motion with so much quality, the Terminator looks like an Osterizer blender.
You can get better performance out of a brushed DC motor if you use an H Bridge with INx interface and apply center aligned PWM's at each input. This is the best algorithm I have seen so far. But in my experience, using a single PWM with a PHASE/ENABLE H Bridge gives good enough results. Like you said, it depends on the application.
Yes, the DaVinci robot would not be using a brushed DC motor, I was simply drawing a comparison between the control capabilities of an H-bridge and a full dual supply swing, where the H-bridge type control would be too unstable. Perhaps I should have clarified this in my previous response...
Simply from a control system standpoint, attempting to get a multiple-order system to approach a single output when only on or off states are allowed introduces a much more complex system to control, as opposed to continuous or discreet steps within fully-on and fully-off.
Stepper motors would be the way to go, I'd think, though the step resolution would have to be to spec.
Controlling the speed of a 1 kW brushed DC motor using a microcontroller is commonly achieved through pulse-width modulation (PWM), which varies the duty cycle of the DC voltage applied to the motor. A chopper circuit designed for a 48 V DC motor can be used for this purpose. Efficient speed control methods include using an H-bridge driver with center-aligned PWM signals or a PHASE/ENABLE H-bridge configuration. While PWM is favored for its simplicity and compatibility with digital control devices such as Darlington pairs and MOSFET drivers, applications requiring high positional accuracy might consider dual supply voltage control or alternative motor types like stepper motors. High-performance robotic systems, such as the DaVinci Surgical System, typically use brushless DC (BLDC) or permanent magnet synchronous motors (PMSM) with advanced field-oriented control rather than brushed DC motors. Resources for DC motor control theory and commercial brushed motor controllers are available online, providing schematics and component guidance. AI summary based on the discussion. May contain errors.
