New Part Day: Lynxmotion Smart Servos

Anyone who shops for robotics kits would have come across a few designed by Lynxmotion. They’ve been helping people build robots since 1995, from robot arm kits to hexapod chassis and everything in between. We would expect these people know their motors, so when they launched their own line of servo motors called Lynxmotion Smart Servos (LSS), it is worth spending a bit of time to look over what they offer.

While these new devices have a PWM mode compatible with classic remote control servos, unleashing their full power requires bidirectional communication over a serial bus. We’ve previously given an overview of three serial bus servos already on the market for comparison. A quick look at the $68-$100 price tags listed on Lynxmotion’s parent company RobotShop made it clear they do not intend to compete on price, so what interesting features do these new kids on the block have?

Digging into product documentation found some great details. Acceleration and deceleration rates are adjustable, which can help with smoother robot movement. There’s also an adjustable level of “stiffness” that adds some “give” (compliance) so a robot won’t have to be as stiff as… well, a robot!

Mechanically, the most interesting internal component is the magnetic position sensor. They are far more precise than potentiometers, but more importantly, they allow positioning anywhere within full 360 degrees. Many other serial bus servos are constrained to positions within an arc less than 360 degrees leaving a blind spot.

An interesting quirk of the LSS offerings is that the serial communication protocol uses human-readable text characters, so sending a number 255 means transmitting a three byte string ‘2’, ‘5’, and ‘5’ instead of single byte 0xFF. This would make debugging our custom robot code far easier, at the cost of reduced bandwidth efficiency and loss of checksum for detecting communication errors. It’s a trade-off that some robot builders would be happy to make, but others might not.

Externally, these servos have bountiful mounting options including some we didn’t know to ask for. Historically Lynxmotion kits have used a wide variety of servo mounting brackets, so they are motivated to make mechanical integration easy. The most novel offering is the ability to bolt external gears to the servo body. A set of 1:3 gears allow for gearing the servo up or down, or you can use a set of 1:1 gears for a compact gripper.

As you’d expect of servos in this price range, they all have metal gears, but they also have the ability to power the motor directly from a battery pack (a 3 cell lithium polymer is recommended). There are additional features, like an RGB LED for visual feedback, which we didn’t cover here so dig into the documentation for more. We look forward to seeing how these interesting little actuators perform in future robotics projects.

Wireless Rover With Android Control


[Radu] spend the first portion of this year building and improving upon this wireless rover project. It’s actually the second generation of an autonomous follower project he started a few years back. If you browse through his old postings you’ll find that this version is leaps and bounds ahead of the last.

He purchased the chassis which also came with the gear-head motors and tires. Why reinvent the wheel (har har) when you’ve got bigger things on your plate? To make enough room inside for his own goodies he started out by ditching the control board which came with the Lynxmotion chassis in favor of an AVR ATmega128 development board. He also chose to use his own motor controller board. Next he added a metal bracket system to hold the battery pack. Things start to get pretty crowded in there when he installed his own Bluetooth and GPS modules. Rounding out his hardware additions were a set of five ultrasonic sensors (the grey tubes on top), a character display, as well as head and tail lights. The demo video shows off the control app he uses. We like that tic-tac-toe design for motion control, and that he added in buttons to control the lights.

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Gum Ball Maze Updated… Now With Robots!

In what is surely becoming an ever-growing Rube Goldberg machine, [Dan] updated his gum ball dispenser to include a robot arm. We looked in on this human lab-rat experiment that rewards successful maze navigation with bubble-gum just about a year ago. As you can seen in the video after the break he’s added several new features to delight users. The original had a maze actuated by an accelerometer and that remains the same. But when the device fires up, the wooden ball is moved to the start of the maze by a Lynxmotion robotic arm. That arm is mounted on rails so it can also move to deliver the gum ball after a successful run. There’s also an anti-jamming feature that shakes the gum ball dispenser to ensure you don’t come up empty.

Whether playing chess or being controlled by a mouse the Lynxmotion has been quite popular lately. [Dan’s] solution uses a vacuum pump to grab onto the spheres (both wooden and gum), similar to the method used with the CNC pick and place from a while back.

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Mouse Controlled Manipulator Arm

[Oleg] worked out a way to use his USB mouse to control this manipulator arm. Using a Lynxmotion AL5D (we’ve seen the AL5A previously) he drives the six servos with an Arduino servo shield. A USB host shield handles the HID end for connecting the mouse. The video after the break says it all, [Oleg] has no problem picking up that figurine quickly and accurately. Sliding the mouse controls horizontal movement in all directions. The scroll wheel moves the claw up and down. And holding the left or right buttons what using the control wheel closes or rotates the claw. All we can say is: Bigger, BIGGER!

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Robotic Chess Opponent

[Dennis] is using a robotic arm as a chess opponent. Rather than using an under-board movement system, a Lynxmotion AL5A robotic arm plucks each piece and moves it to the next space. He tells us that he’s using a Python script that he created to process the moves and decide what’s next. That must mean he’s using a webcam to capture the location of the pieces on the board. About half way through you can see the robot run into one of the pawns. We’d like to know if he has problems with picking up the pieces as the game progresses and they get further away from the center of each square. From what we can see, looks like a great job!


We know it was just two days ago that we were ranting about the hexapods known as Phoenix, and their creator [Zenta]. In the comments on that post, [Bluehash] pointed us to [Zenta’s] latest creation. This is A-pod. The sheer articulation and believable motion here made this robot worthy of a post all it’s own.  A-pod has a 2 dof “tail” and a 3 dof head with a total of 25 servos to drive it. The addition of the head adds so much character, add some face tracking and it would really blow us away. Well, after it fetched us a beer. He notes that he’s still working on the leg mechanicals, so it doesn’t do much walking yet.