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.
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
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.
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
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
Thanks a lot, you replied faster than Lewansoul support!
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.
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.
Hi!
Great review. Thanks!
Do you know what is the the cable length? I see references to both 10 and 20 cm.
Also, what type of connectors do the cables have?
https://releasetheinnergeek.wordpress.com/
Thanks for the fantastic review. I am interested in trying to use the base of the LeArm to control a laser. The laser would point to a position on a construction site where a plumbing fixture is to be located. Long story short, I would love to be able to use my own software to control one to 3 servos. Are you interested in doing this job? If not can you recommend anyone? Thanks!
I would suggest using mirrors on a galvo, like a laser show. You could even draw shapes at the location. You can buy them for a couple hundred dollars on AliExpress. They are multicolored too.
making the servos NOT start a move at exactly the same time.. See:
I BOUGHT 5 LX-16A Servo motors.
I need to set the motors to swing 180 degrees
ID 1 will start and return to 0 degrees.
ID 2 will start 5 to 10 seconds after ID 1
ID 3will start 5 to 10 seconds after ID 2
ID 4 will start 5 to 10 seconds after ID 3
ID 5 will start 5 to 10 seconds after ID 4.