The steps of setting up and using SOLO alongside with ARDUINO

0) Turn off the system

1) Apply the Wiring

To start with SOLO first you need to provide the Wiring of SOLO to ARDUINO as following:

As you can see SOLO is also capable of supplying ARDUINO Directly through its 5V output and as a result you will not need to have ARDUINO connected to any other devices like a PC to provide you the power.

2) Select the Motor type using Piano Switch

3) Reset the Kp and Ki potentiometers

4) Turn On the system

Now you can turn on the main supply connected to SOLO’s power input (8-58V) and SOLO will immediately boot up with a blinking “E2” LED while “E1” LED is off which is the indication of a safe startup with no errors or malfunctions ( like over current, over voltage, … )

5) Put SOLO into speed control Mode

6) Put SOLO into closed-loop mode

since the control type we are using here is among the closed-loop controls, you need to push the Piano switch number 5 down, when you do that, SOLO in less than a second will identify your motor parameters and it will store them on it’s non-volatile memory, during this time if the shaft of the motor is free, you might witness some little vibrations which are totally normal. So as long as the Piano Switch number 5 is down, the last saved parameters will be used, even if you turn off the whole system and turn it back on again, the parameters will remain safe until re-identify them by pushing down and pulling up the same pin in the piano switch. In General Under the following conditions you need to pull up and pull down again the piano switch number 5 :

• In case of changing the Motor
• In case of changing the wiring of the motor ( not mandatory but better to be done)
• The very first time you run SOLO and you put it into closed-loop ( after receiving the factory made module )

7) Tune The Kp and Ki gains

Turn a little bit the “Kp” potentiometer( like 5 degrees in counter clockwise direction ) and for a very small amount “Ki” ( much less than Kp, around 1 or 2 degrees), the best is you watch the video up there to master this. In general these two potentiometer are like some gains and in a simple language they can be defined as:

Kp: defines for you how fast your motor should react and reach the speed you asked, so if you increase this value, your motor will be more reactive, but too much of this gain might make vibrations, so you need to tune it enough. Also another effect of this gain will be how “harshly” the controller ( here SOLO ) should react to the variation of the load on the shaft of the motor to keep the speed constant, so in case of using this functionality in a mobile robot as an instance, if you increase Kp of SOLO, and the robot reaches to some ramps, it will adjust it’s speed faster but also it might make your robot too fast. So it’s not always good to increase this gain, it totally depends on your system.

Ki: defines how good your motor during time should reach the goal, so by increasing this value your motor might reach the goal slower but more consistent. Also by increasing this gain too much your motor might get unstable. So you need to tune this similar to Kp with patience and accuracy.

In general the first time you tune these two gains, as long as you are using the same Motor in the same system you won’t need to touch them, it’s only the matter of the first time.

8) Send PWM pulses from ARDUINO to SOLO

 9) Limit The amount of current fed into your motor:

You can limit the amount of current fed to your motor using the connection shown in the wiring section to “P/F” input of SOLO. Again here, you can use PWM pulses with any frequency above 5kHz, and by changing their duty-cycle the value of the current limit will change based on the following formula:

The current Limit value = ((100 – duty cycle of PWM at P/F input)/100) * 32

For example if we put the duty cycle at 80% on “P/F” input, the maximum current allowed into the motor will become 6.4 Amps: ((100-80)/100)*32

As you see, this input works in reverse, so if you leave it open, the maximum allowed current into your motor will be the default value of 32A and if you apply a 100% duty-cycle PWM into “P/F” input, the current limit will be set at 0 (no current allowed into the motor). If you don’t want to use this feature you can leave this input unconnected.

You can limit the amount of current fed to your motor using the connection shown in the wiring section to “P/F” input of SOLO. Again here, you can use PWM pulses with any frequency above 5kHz, and by changing their duty-cycle the value of the current limit will change based on the following formula:

The current Limit value = ((100 – duty cycle of PWM at P/F input)/100) * 32

For example if we put the duty cycle at 80%, the maximum current allowed into the motor will become 6.4 Amps: ((100-80)/100)*32

As you see, this input works in reverse, so if you leave it open, the maximum allowed current into your motor will be the default value of 32A and if you apply a 100% duty-cycle PWM into “P/F” input, the current limit will be set at 0 (no current allowed into the motor). If you don’t want to use this feature you can leave this input unconnected.

Results

As you can see in the image below which is a real time plot of Torque-Speed of a DC brushed motor controlled by SOLO in closed-loop sensorless speed control mode. As you can see, the speed of the DC motor ( green track) remained constant even at those moments where a load applied to the shaft of the motor, you can find the moments that the load has been applied from the Torque (the red track) , because whenever a load has been applied on the motor, SOLO automatically increases the Torque of the DC motor to overcome the load and keep the speed constant.

Read more about SOLO ARDUINO Environment Here .