Understanding the HB-25: I don't.

Bill Chennault

All--

I am trying to understand the HB-25. Is it a servo controller? A motor controller? A motor controller that mimics a servo controller? Does it perform PWM? Or, is another device necessary for PWM using the HB-25?

Thanks!

--Bill

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You are what you write.

Mike Green

The HB-25 is a motor controller that mimics a continuous motion servo controller. It uses PWM on the motor side of things to allow variable speed with high torque, but the microprocessor side of things only sees a standard servo controller. What's different is that the HB-25 does not require repeated servo control pulses unless the pulse width changes (although it behaves properly if it does get repeated servo pulse of the same width).

stamptrol

Hi Bill,

Just working my way through the HB-25 myself.

Its a motor controller, for sure. Zero to full speed, Forward and reverse, so is a full H-bridge.

The interface is quite slick and does use the familiar servo command pulses. PULSOUT

So if you send the "zero" pulse width, the drive stops. Send the pulse width associated with a small movement clockwise, say and the motor will run at a low speed in one direction. Send a pulsewidth as if you were commanding the servo to the clockwise direction and the motor will run in the other direction at a speed proportional to the pulsewidth.

Also built in is the capability to only see the change in command pulsewidth, so it is not necessary to keep refreshing the command as in the case of a servo.

All in all, a very nice product at a good price.

Cheers,

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Tom Sisk

http://www.siskconsult.com
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allanlane5

The "zero" pulse width being a pulse width of 1.5 mSec, which says to a continuous servo "stop!"

So yes, it's a motor controller that runs a DC motor, while to the processor commanding it, it looks like a continuous rotation servo.

This is really quite clever. This lets you 'test' with a continuous rotation servo, gives you forward and reverse at variable speeds, and a 'stop' command, all with a single pin from a BS2.

Oh, and with the integrated H-Bridge and it's own controller, yes it does PWM to the DC motor side to implement that speed control.

Bill Chennault

Mike and Tom and allanlane5--

Thank you. It is what I had hoped.

I am building a skid steer using double-sided timing belts and timing belt pulleys from SPD/SI and bearings from VBX. Initially, I will use two of those little 29oz-in NEMA 17 Jameco stepper motors at something close to 4:1 to drive the·0.75" tracks. Although I am pretty sure the Jameco steppers (one of which I used in my stepper-driven rotary table project) do not have the power I need, I REALLY want to use the Peter Norberg Consulting BS0710-USB stepper controller in a more complex environment; it will control two stepper motors and is ideal for my application (given the lack of torque using the Jameco steppers).

After I experiment using the steppers with the skid steer robot, I will either go to two AX-12+ "servos" or two Banebot gearmotors with factory calibrated encoders (128 CPS). No matter which I choose, I will use the other next. The gearmotors will give me all the torque I can use and the gearmotors will be driven by two Parallax HB-25s.

I have been retired for exactly FOUR DAYS.

--Bill

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You are what you write.

D Faust

Bill, this isn't about the HB-25s but,

In a thread in the sandbox, the aperages of the spur gearmotors·by Banebots·are in question.· You might want to check out this data sheet from the manufacturer. http://www.dswbrand.com/electromotor.php

The thread is: http://forums.parallax.com/showthread.php?p=659160

Hope this helps.



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D Faust

Bill Chennault

D Faust--

Thank you for the "heads up." I always TRY to question just about everything, but I would have probably not thought of that one, possibly because none of my applications are critical functions.

To date, the only motors I have used from Banebot are the planetary gear motors, but I suppose the same problem could be present in that line, as well.

I wish Maxon would sell to normal human beings.

--Bill

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You are what you write.