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  • Author Author: weiwei2
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Is this motor powerful enough to run the chasis? -Automatic Weeding Robot #4

weiwei2

Reality struck. despite its 'formidable' looking track, my chasis cannot move properly on the grass.

The video shows that it struggle to move on my garden grass. The motor driver is a ST L298 based motor driver.

It is dual channel but limited to 2A per channel. As one can see on the video, my power supply is also running into the >2A range

and sometimes overload.

 

One way to solve this is to make use of current capable motor driver. I am right now evaluating the option. i do want to try to change to my maxon motor but

i am also bit unknown if it is more powerful or not. In fact i also have 2 DC motor claimed from power tool. However, the biggest problem of using  those are the lack of planetary gearhead suitable for my chasis. Hence for now i put this option aside.

 

Now, i am thinking whether i can use higher current to drive the chasis. It comes with Donshun's http://www.dongshunmotor.com/zl/clxjs/DS-33RS395.pdf

a motor with label DS-33RS3950126700-74.8k

 

In order to move a DC motor there is a few choice, first is simply use a single relay to turn it on and off. This is the simplest form of dc motor control

and i do have a relay shield on hard. The downside of this is there is no speed control, as the motor simply runs at full speed. I actually have tested the motor by connecting it directly to a 30A capable power supply, and observing its stall current. It should be roughly 2.3A, although i also can see sometimes up to 2.8A.

 

The second choice is to use a half bridge, or construct it with 2 bipolar transistor or 2 MOSFET. MOSFET Is more efficient in that it can offer lesser power dissipation.

 

Lastly, it is H-bridge. H bridge is a circuit capable of switching the voltage polarity applied to a load, in this case the motor. L298 itself is a H-bridge. It is to be noted that one can also use 4 relay to make a H-bridge. Alternatively, a DPDT relay can be used to do it. Well i motor driver that can provide higher current for now. i use to have some 10A dc motor driver shield but unsure where they are hiding right now

 

My next step to determine if under higher current allowed by L298 can i run the chasis on grass. The most directly testing it is to drive the motor directly with power supply. As it seems, the culprit in this case is indeed L298. When using higher current, the chasis can run on the field.

 

image

 

So, the next easiest way is to either use a relay driver to power the chasis, or use a higher current motor driver.

 

 

References

https://www.picotech.com/library/application-note/some-power-pwm-drivers-for-electric-dc-motors

Parents

  • The real issue is that you need more torque rather than speed.

    By using the motors to directly drive the belt you put all of the force directly on the motor.

    To get more torque, you want to used various gearing to turn the speed of the motor into more force to drive the belt.

    By allowing the motor to run at higher speeds at low torque, you greatly reduce the current needed to move the chassis.

     

    So look into using gears and or belts to enable your motors to create more torque.

     

    DAB

Comment

  • The real issue is that you need more torque rather than speed.

    By using the motors to directly drive the belt you put all of the force directly on the motor.

    To get more torque, you want to used various gearing to turn the speed of the motor into more force to drive the belt.

    By allowing the motor to run at higher speeds at low torque, you greatly reduce the current needed to move the chassis.

     

    So look into using gears and or belts to enable your motors to create more torque.

     

    DAB

Children