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Question 1: If you are satisfied with your robots stopping distance, than you don't need electronic braking. With a heavier or faster robot, its quite useful. The larger the machine, the more inertia becomes a important design factor. For example, a form of electronic braking is used by open-pit mining dump trucks. Ordinary dump trucks, being much smaller, ...


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While there are other H-bridges that handle higher current and it might be cost-effective to just buy a higher-amperage pre-packaged ESC (electronic speed controller), you might also consider using higher-voltage motors (1, 2). Adjust the voltage up or down as the H-bridge amperage limit allows. Also consider using a slip clutch between the motor and the ...


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First a bit about motors. Stall current is the current drawn by the motor when the recommended voltage is applied and the motor is not turning due to a load. Alternatively, the no load speed is the speed the motor will spin at under no load. In this state it will draw a minimum current. Here is an example torque/speed current for a DC motor: Source: ...


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The behaviour you're describing seems to be correct (as described in the Texas Instruments L293 datasheet - which should be the same as ST's variant). Here's an example of how to wire 3 different motors (please note the indicated diodes are internal to the L293). The idea is that Vcc1 (pin 16) should be associated with your logic inputs: pins 1, 2, 7, 9, 10 ...


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It is not possible to use the micro-controller directly as an H-Bridge. A micro-controller is a micro-controller and an H-bridge is an H-bridge. You need both of them to control a motor (or something equivalent). I will suppose that you are using motors and not servo. Let's say you want to use your micro-controller as an H-bridge. You have two cables from ...


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keep it simple: when A is H-Level and B L-Level then Q1 and Q4 are in the saturation region so the current flows in the direction as follow: on the other option: A is L-Level and B H-Level the rest of the options: A=B= H-Level or A=B= L-Level are not going to move the motor


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Basically (in reality anything have a sligth aspeact of everything else, nothing is ideal) the DC motor is mainly inductance in serie with small resistance. Your typical use is close Q2+Q3 and send PWM to Q1+Q4 (or vice versa). When PWN is on, Q1+Q4 are open and current goes to DC motor from left to rigth. It start to rotate (or increase rotation when ...


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Yeah, just like you'd PWM to have some kind of variable drive torque between zero and the torque provided by maximum current, you'll PWM to have some kind of variable brake torque between free-wheeling and maximum electric braking. The only thing to be careful of is that your electric braking power needs somewhere to go, and your power electronics and/or ...


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You connected your (one) motor to the battery and got 70mA draw. You use a two motor driver and are seeing 144mA draw. I'm not sure what the problem is. What command are you sending to the second motor?


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q1 and q3 will never really turn on if the voltage applied to A or B is less than the motor supply voltage, NPN transistors require that the base voltage is greater than the emitter voltage by 0.6v, lets say without the motor running its emitter is sitting at a random value of 2v, when you apply say a 5v signal to it, the emitter will then only every rise to ...


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FYI, iRobot has released the spec for the motor interface here: http://www.irobot.com/~/media/MainSite/PDFs/About/STEM/Create/Create_2_Wheel_Hack.pdf


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The motors get a PWM'd battery voltage which is around 18V. I assume it is safe to run at that voltage at 100% duty cycle. I imagine you could run a higher voltage but you run the risk of burning out your brushes. Lower voltages work fine if your bot is small. I have successfully run a small Roomba wheel module robot off of 8 AA batteries (about 12V).


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Of the choices you presented, PWM + BJT/FET is most efficient. An H-Bridge is a prime example of that. -BJT's dissipate heat in proportion to their "on-ness" -FET's dissipate heat based on their (very low) on-state resistance, plus a small loss during the actual switching. By PWM'ing, you are approximating an analog voltage in proportion to the BJT/FET ...


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This one may be a nice board for you http://www.pololu.com/product/2502 they say it is unavailable, but you may find something.. or just take two of them: http://www.pololu.com/product/1451


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I'm not really familiar with Atmel microcontrollers, but I'm assuming you're using some Arduino variant. Here's a pretty thorough tutorial about using an Arduino with a SN754410 h-bridge (found it via the SN754410 Sparkfun entry). It seems the only thing the tutorial lacks is controlling the motors via PWM, which of course means you will only be able to ...


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What Brendan said. However, there is an out if you want to reach for it: once you have determined the actual stall current for your situation, from the motor armature resistance, supply voltage, and the whopping 1.4V drop in the L293, if you pulse the drive to the motor such that the average current through the L293 is the rated 600mA or less, then it ...


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