LewanSoul Lobot LX-16A Serial Servo Review

I stumbled upon these LewanSoul LX-16A Servos the other day on Amazon while searching for standard digital servos. These servos are digital serial bus servos. That means they use a serial protocol on a bus rather than a PWM signal. I have used bus servos before, but the $12 price got my attention. That competes well with plain old PWM servos.

Serial bus servos have some real advantages over standard PWM servos.

  • Wiring: The wiring can be a lot simpler because you can put all your servos on a single 3 wire bus. Each servo has 2 connectors to make daisy chaining easier.
  • Higher resolution: The resolution is typically higher. It depends on the way they sense position. These use a high accuracy potentiometer and list 0.24° as the resolution.
  • You can set the speed: You can set a destination and speed for each move.
  • Set the range: You can limit the range of the servo. This is great if the using the full range would crash a joint on your machine.
  • Continuous turn mode: There is a speed adjustable continuous rotation mode on these, but absolute distance moves cannot be done.
  • Motor On/Off: Turn the motor off for manual movement.
  • Feedback: The communication is bi-directional so you can query a servo for…
    • Position: If you manually move a servo, you get its position. This is great for recording “poses” or setting range limits.
    • Temperature: You can read the current temperature of the motors.

Compared to Robotis

I have used the Robotis Dynamixel XL320 servos before but these are a lot stronger and the XL-320 has a weird, plastic rivet, mounting systems that I am not fond of.

Here is a size comparison with a XL-320.

Specs

Spec LX-16A XL-320
Max. Torque 17 kg-cm 4 kg-cm
Resolution 0.24° 0.29°
Range 240° and Continuous Rotation 300° and Continuous Rotation
Speed 62 RPM 114 RPM
Weight 52g 16.7g

Usage

To use the servos you need to use one of their controllers. The most basic controller just converts a USB or TTL serial signal to their protocol. The controller is small and low cost ($10). You can send commands via a USB (Com Port) or via the TTL pins.

Setup Program.

They have a setup program.  The program is Windows only and I had to run it in Administrator mode to get it to work. This makes setting up the servos easy, but you could write your own program if you don’t want to use theirs.

TTL Control

They also provide some Arduino Sketches. They worked fine and are a good place to grab some code if you are writing your own program.  The sketches use the Arduino hardware TX and RX pins. That conflicts with uploading, so you need to disconnect the controller every time you upload. I edited the sketch to use SoftwareSerial on some other pins and that made playing with the code a lot easier.

First Impressions

I found the servos very easy to use and they appear to be strong and responsive. I think they will be a good option for my on my machines.

Next Steps

I want to test these in a real machine. I thought I might try to make a slightly larger version of my Line-Us clone. That would be a good comparison of accuracy. I might try one day build on it tomorrow.  I can probably get a machine designed and built in a day, but the controller programming would need more time.

 

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7 Responses to “LewanSoul Lobot LX-16A Serial Servo Review”


  1. Michael Shievitz

    These are dynamixel compatible and should run directly on the open cm controller after assigning the ID etc.

    I am still trying to source aluminum brackets for them. Met me know if you find anything

  2. bdring

    The sell them with and without the brackets on Amazon. I bought my first one with brackets and then accidentally 2 more without the brackets. I actually 3D printed some brackets and they are good enough for my test bot.

    I have not seen the brackets sold individually.

  3. Eddie

    Hi,

    Thanks for your review. I recently purchased a kit with 5 of these Lewansoul motors but I can’t find the software or documentation anywhere to download.

    Would you be so kind to post a download link for that info if you have it.

    Thanks in advance.

    Eddie

  4. bdring

    My servos came with a card listing the location of the software.

    It is in a public Dropbox folder. I had to run the program in administrator mode to get it to work.

    Software: http://bit.ly/2rJshh6
    Videos: http://bit.ly/2t4MNwS

  5. Eddie

    Thanks a lot, you replied faster than Lewansoul support!

  6. Kyle

    Hey, I’m playing around with one of these and Arduino for a robotics project. When you were using these did you notice any odd behavior when commanding positions? I’ve noticed that there is pretty extreme overshoot if I command the servo to move from one extreme angle to another. For instance, if I start at position zero and move to position 1000, the servo appears to overshoot by about 30degrees, then pause for a second, and then correct back. The really weird thing is that sometimes it undershoots, pauses, and then corrects forward to the commanded position. Does that sound consistent with anything you’ve observed? I’m wondering if there’s a way to avoid this.

  7. bdring

    I did see this, but less than you describe. There was some overshoot. The faster the move, the more I would see. The worst I saw was about 3 degrees. I never had them under much load though.

    On some bus servos you can adjust PID parameters. I did not see any mention of that for these servos.

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