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Motor driver for a haptics application

Anders Larsson
Prodigy 10 points
Other Parts Discussed in Thread: DRV8412, DRV8840, DRV8842

Hi all,

I'd like some help on choosing a suitable motor driver / H-Bridge for a haptics application.

Basically it is a closed loop control application where brushed DC motors (Maxon) will be outfitted with quadrature encoders. The encoder values will then be read by a microprocessor which in turn control the motors via PWM. For a haptics application like this the motors will be resisting the user and basically stalling instead of driving.

What might be of importance too is that the motors must be able to switch directions really fast, < 1 ms (e.g. locking the mechanics in a specified position). 

The motors we're looking at using are 60W - 100W at 25 Volts. I found the DRV8412, is that a good fit for this project?

Thanks for your help,

 Anders 

  • 0
    TI__Expert 7455 points

    Hi Anders,

    The DRV8412 will definitely be able to tackle this application. Other devices that I can think of are DRV8840 and DRV8842 which are 5A H Bridges with current regulation.

    The reason why I bring up current regulation is because you mentioned controlling the stalling point of the DC motor. This can be achieved by controlling the current magnitude, and hence torque. Of course, another way is to change the PWM duty cycle according to position error by using a PID loop. They are both almost the same thing, as in one case you adjust a PWM duty cycle (or adjusting the voltage which then translates into adjusting the current), and in the other you adjust an analog voltage which in turns adjusts the duty cycle (or adjusting the current which then translates into voltage).

    Some other items to look at are:

    DRV8412 has lower RDSon so can run for longer periods of time at 4A.

    DRV8840 has PHASE/ENABLE interface, whereas DRV8412 and DRV8842 have INx interface.

    DRV8840/42 occupy less space than DRV8412, but give you less current capability.

    Hope the info helps.

    Best regards,

    Jose Quinones