Stepper motor cannot start at full speed?

[mawyatt]

First off, the Trinamic are not just a stepper motor driver but a fully integrated micro controller with a H bridge driver. These fully integrated single chip controllers with the mentioned capability, like the noise reduction, velocity, acceleration and position control, dynamic current manipulation and flexible interfaces are readily available and not expensive. These devices don't just switch between ground and the supply in a simplistic manner, but coordinate a switching means to keep the coil current flowing continuously while returning energy to the supply, they can also modify this current profile while the motor is in motion adapting to the load changes.  We haven't looked at the latest stepper motor control chips in the past ~4 years, maybe something new has emerged from another supplier, so please provide information??

We routinely achieve accurate open loop 2.5 micron full steps when the motor is coupled to a THK KR20 linear rail with 1mm screw pitch, and achieve open loop sub-micron steps utilizing micro-stepping. Regarding BLDC motors and FOC techniques, we never seriously looked at this because the implementation was too complex and expensive, and seemed geared towards much higher power levels relative to the Trinamic solution we employed. Please provide information on a FOC controller and BLDC motor that can achieve equal performance to say the common TMC5130 or TMC5160 or 61 chip and a typical NEMA 17 400 step 2A motor without utilizing a feedback controller or sensor to achieve the mentioned performance at a similar cost?

We ran that "fun" experiment many many years ago using a DC coupled audio amp, the motors got so hot, so quick that you could burn your finger, don't ask how I know 

Actually all our experimenting has been done over the past couple decades, and evolved to the Trinamic and THK solutions, and within the past couple years to developing a system based upon piezo electric control achieving 10s of nanometer resolutions.

Do agree the Trinamic data sheets are way too complex, the customer service isn't good either (we aren't an OEM). This may be a way to keep smaller users at bay, and filter thru to the OEMs. So the message is the chips are good, the service isn't

Edit : Few images of single, dual, triple and quad axis Trinamic based controllers, and some custom Piezo Electric controllers.

Best,
 

[drussell]

People have been referring to the rotating part of a motor as the armature for such a long time it has become a recognized term for 'the spinney part'.

You are simply incorrect.  The "spinney part" is called the rotor.  It may or may not be an armature.

In electrical engineering, an armature is the component of an electric machine which carries alternating current.  The armature windings conduct AC even on DC machines, due to the commutator action (which periodically reverses current direction) or due to electronic commutation, as in brushless DC motors.  The armature can be on either the rotor (rotating part) or the stator (stationary part), depending on the type of electric machine.

The parts of an alternator or related equipment can be expressed in either mechanical terms or electrical terms.  Although distinctly separate these two sets of terminology are frequently used interchangeably or in combinations that include one mechanical term and one electrical term.  This may cause confusion when working with compound machines like brushless alternators, or in conversation among people who are accustomed to work with differently configured machinery.

In most generators, the field magnet is rotating, and is part of the rotor, while the armature is stationary, and is part of the stator.  Both motors and generators can be built either with a stationary armature and a rotating field or a rotating armature and a stationary field.  The pole piece of a permanent magnet or electromagnet and the moving, iron part of a solenoid, especially if the latter acts as a switch or relay, may also be referred to as armatures.

[CaptDon]

It's all good.....I am at the point where at times you need to tell the traction motor guys "Take the round part out of the square part because it doesn't go around anymore. Put a new round part in there and replace those big flat things on the ends with new flat things and if any of the little round balls fall out use different flat things. Rotor, Stator, Armature, really, half the guys in the shop call it one thing and half the guys call it something else, I guess because some of them grew up with the D.C. traction motors and called the spinning part the armature and the other guys grew up with A.C. traction motors and call the squirrel cage thing the rotor. Personally I couldn't care less as long as it gets fixed. Why do locomotive drivers have 4 terms for what they drive, Motors, Power Units, Engines, Locomotives? Really, who cares. All I do is design and build the part that takes 1400vdc and converts it to 3 phase A.C. in six different inverter stacks to make their spinning parts spin no matter what the blue collar rank and file guys call it. I did use stepper motors to move the contactor in the Crank Transfer Switch because as it traverses it encounters wildly different mechanical resistance across six inches of travel and I wanted to eliminate the monkey motion and have smooth travel produced by a stepped lead screw. And I incorporated acceleration and deceleration since we all know 'steppers won't start at full speed', and an LVDT position sensor to tell me where the thing was in its little world of controlled motion. So yup, I agree, I'm wrong!

[Hellmut1956]

An interesting attractive way to make life easy and inexpensive without giving up and on the Trinamic stepper motor controllers. Those are the SilentStepSticks. in 3D printers today the most frequently used ones are the SilentStepSticksTMc2208 and SilentStepSticksTMC2209. In other applications using stepper motors to drive a CNC for example, depending on the torque you want a stepper motor to deliver those SilentStepSticks boards are still a good choice. If you do not want to use stepper motors that offer a very high torque the SilentStepSticksTMC5160, TMC5161, and the old TMC5160hv. The SilentStepSticksTMC5160, TMC6161 have the H-Bridge drivers outside the Trinamic Chip and so being able to better get rid of the heat. Using the heater dissipation on the Trinamic IC improves the heat dissipation.

[mawyatt]

Watch out for certain SilentStepSticks, some time ago recall the ones based upon the TMC5160 could not be configured to allow access to the advanced control algorithms because the PCB had a critical chip pin grounded, and was under the chip package and not accessible to cut unless you removed the chip. These were designed to be plug in replacements for 3D printers and could only do Step and Dir control, and thus limited capability. Being a plug in replacement they just worked like a regular stepper driver but with lower noise, and utilized the same controlling software. This was brought up to the Trinamic some time ago, and they finally modified the PCB to allow full access. The BOB style we use for the TMC5130, 5160, 5161 & 5072 allow full access to all functions, and don't cost much more ($5) than the StepStick but are larger footprint. If you are creating something new, consider the BOB style if space isn't an issue.

Does anyone know if any of the new 3D printers are utilizing the Trinamic chips with control algorithms rather than just Step and Dir control?  Being new to 3D printing (and 3D modeling) just ordered a 3D printer (per recommendation) that apparently uses the SilentStepStick, but doubt it uses the control algorithms.

Best,

[ajb]

Does anyone know if any of the new 3D printers are utilizing the Trinamic chips with control algorithms rather than just Step and Dir control?  Being new to 3D printing (and 3D modeling) just ordered a 3D printer (per recommendation) that apparently uses the SilentStepStick, but doubt it uses the control algorithms.

If you're referring to the motion control algorithms, including acceleration management and positioning, probably not, because those control systems only work on a single axis.  You can run multiple axes simultaneously but they won't be coordinated such that something like a 3D printer will move from one position in X/Y/Z to a different position in X/Y/Z in a straight line--the axes will accelerate and decelerate as individually programmed, so if the axes have to move different distances then they'll finish at different times, making them useless for any kind of coordinated motion.  Well, you could sort of do coordinated motion by calculating the correct per-axis acceleration and velocity parameters and sending those to the controllers prior to every move, but that would be kind of silly and would be hard to get good results.  Much easier to have one motion controller directing everything together.

I think Trinamic have some more sophisticated motion control system that are independent of their motor drivers that may be able to do coordinated multi-axis motion. 

[mawyatt]

Does anyone know if any of the new 3D printers are utilizing the Trinamic chips with control algorithms rather than just Step and Dir control?  Being new to 3D printing (and 3D modeling) just ordered a 3D printer (per recommendation) that apparently uses the SilentStepStick, but doubt it uses the control algorithms.

If you're referring to the motion control algorithms, including acceleration management and positioning, probably not, because those control systems only work on a single axis.  You can run multiple axes simultaneously but they won't be coordinated such that something like a 3D printer will move from one position in X/Y/Z to a different position in X/Y/Z in a straight line--the axes will accelerate and decelerate as individually programmed, so if the axes have to move different distances then they'll finish at different times, making them useless for any kind of coordinated motion.  Well, you could sort of do coordinated motion by calculating the correct per-axis acceleration and velocity parameters and sending those to the controllers prior to every move, but that would be kind of silly and would be hard to get good results.  Much easier to have one motion controller directing everything together.

I think Trinamic have some more sophisticated motion control system that are independent of their motor drivers that may be able to do coordinated multi-axis motion.

Thanks, that's a good point about coordinated multi-axis control since they wouldn't know what the other axis is doing when using the internal motion control algorithms. We did some XYZ movements with separate controller/drivers utilizing the built-in signal axis motion control algorithms, but they weren't tightly controlled wrt each other, and only the Z axis was of concern regarding precision. This seems like an opportunity for Trinamic to make an axis interface to allow direct "talking" between the X, Y and Z axis controllers/driver, or better a single multi-axis chip with new multi-axis motion control algorithms. To keep the chip cost reasonable they could use external power fets to drive the motor coils like they do with the TMC5160. With all the popularity of the 3D printers I'm surprised this isn't a product yet!!

Anyway, thanks for the dialog and this explains why the first SilentStepStick TMC5160 didn't allow advanced motion control algorithm access, the later one has a 0 ohm resistor to set the interface to allow such.

Best,

[langwadt]

Does anyone know if any of the new 3D printers are utilizing the Trinamic chips with control algorithms rather than just Step and Dir control?  Being new to 3D printing (and 3D modeling) just ordered a 3D printer (per recommendation) that apparently uses the SilentStepStick, but doubt it uses the control algorithms.

If you're referring to the motion control algorithms, including acceleration management and positioning, probably not, because those control systems only work on a single axis.  You can run multiple axes simultaneously but they won't be coordinated such that something like a 3D printer will move from one position in X/Y/Z to a different position in X/Y/Z in a straight line--the axes will accelerate and decelerate as individually programmed, so if the axes have to move different distances then they'll finish at different times, making them useless for any kind of coordinated motion.  Well, you could sort of do coordinated motion by calculating the correct per-axis acceleration and velocity parameters and sending those to the controllers prior to every move, but that would be kind of silly and would be hard to get good results.  Much easier to have one motion controller directing everything together.

I think Trinamic have some more sophisticated motion control system that are independent of their motor drivers that may be able to do coordinated multi-axis motion.

as far as I can tell the "big" CNCs using FPGAs like MACH3/4 and linuxCNC basically does it by; every millisecond or so they calculate and tell each motor how fast to go to hit the next millisecond "waypoint" then wrap a PI loop around that using either using encoder feedback in the case of servos or number of steps taken in case of steppers

I think trimanic has a controller that does similar, writing speed and reading position via SPI from three drivers

since on the 5160 you can set the current in each coil directly and it has input for a quadrature encoder might be possible to do FOC and closed loop stepper, though I seem to remember that it might not be possible to use the decoder unless you also use the motion control

[phil from seattle]

Motion control systems like Marlin or GRBL coordinate steppers so you can make multiple axes do what you want - straight lines, curves, etc.  At the heart of CNC machines, 3D printers, etc.  If you have a need to make the steppers work together, I would look into something like GRBL or Marlin.

[Hellmut1956]

@mawyatt: Please look more detailed into the datasheet of the Trinamic parts. The behavior you mention indicates that the Trinamic stepper driver has not been set up properly. On this page at the Trinamic website, you find the different technologies Trinamic drivers offer and CoolStep is the one where the current is controlled by the actual load, so that, adding a safety margin only that amount of current flows through the coils of the stepper motor that is required to handle the load. Effectively this controlling the current flow by using a PWM and the much higher voltage applied allows choosing a stepper motor that does not have to offer the torque required at peak loads. The Trinamic stepper motor supporting CoolStepand that has been set up properly can increase the current flow for a short period of time to 120% generating this way 120% torque.

I use this CoolStep as I have made a stepper motor to be the winch in my model sailboat to implement a smart control of the sails that mimics the way it was on the original sailboats at the beginning of the last century. I have tried to follow as close as possible the design of the Endeavour".

Please do not see it as criticizing you, it is just sharing what I learned about 7 years ago. The Trinamic IDE is in combination with a proper evaluation board the vehicle I did use to learn about stepper motors. The stepper motor in my model sailboat is powered by a battery pack consisting of 12 cells LiFePO4 connected in series. Saving energy is key to achieve longer times at the pond. The CoolStep functionality has a dramatic impact in my model. Originally I had planned to use electrical brakes to reduce the power consumption while the stepper motor is holding its position!



CoolStep™
The sensorless load-dependent current control CoolStep is based on the StallGuard load values. It detects the motor load by changes in the back EMF and adapts the current to the actual load conditions. As a result, CoolStep always drives motors at their optimum current, saving tremendous amounts of energy by reducing the current to a minimum when the motor has a light load, and increasing the current when the load increases. This not only keeps the motor cool, it also allows short current boosts. CoolSteps improves reliability of the entire system.

[mawyatt]

Where did we indicate that these Trinamic devices work differently that what you've just describe above? The coil current is normally not allowed to return to zero during the commutation process, and the PWM keeps the average current at whatever level is required with the particular algorithms selected at that particular time. We started using the Trinamic devices probably 5~6 years ago, didn't know about them and were using the Pololu controllers before. Our 1st Stepper control design dates back ~40 years, where a design was created out of discrete logic and bipolar transistors to drive a precision mirror system in the electro-optic Remote Sensing Chemical Agent Detector development, called XM21. This employed position feedback, so was a somewhat closed loop system, not pure open loop.

Anyway, glad you like these Trinamic devices, we sure do!! Maybe others can benefit from their performance.

Best,