FET Based Motor Driver Is Better Than L298N

If you want to build a small robot with a motor, you are likely to reach for an L298N to interface your microcontroller to the motor, probably in an H-bridge configuration. [Dronebot] has used L298N chips like this many times. In the video below, he uses a TB6612FNG instead, taking advantage of the device’s use of MOSFETs. The TB6612 may be a little more expensive, but it’s clearly worth it.

You can get breakout boards for the tiny chips. [DroneBot] looks at several ready-to-go breakout boards. They are not drop-in compatible, though. For example, the L298N can operate motors from 4.5 to 46V while the TB6612 can go from 2.5 to 13.5V on the motor voltage. The L298N also handles more current. However, because of its relatively low efficiency, it needs a heat sink. The TB6612 boasts up to 95% efficiency and also has a low current standby mode. Of course, the TB6612 drops much less voltage which is great if you are using low voltage motor.

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Robot Insect Survives Swatting

There is an old saying, that ‘the hand is quicker than the eye;, but somewhat slower than the fly.” However, with a little practice you can swat a fly, although it sometimes doesn’t seem to faze the fly. École polytechnique fédérale de Lausanne (EPFL) has announced they have used nanotech to build a 1 gram possibly untethered, autonomous robotic insect that has enough processing power and sensors to recognize black and white patterns. Artificial muscles provide propulsion. But there’s the kicker: it can survive a strike with a fly swatter.

In the video you see below, the robots can move at 3 centimeters per second and there are two different versions. The first is a tethered system using ultra-thin wires. This is the version that can be folded, smacked, or even squashed by a shoe and continue moving.

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Quadruped Robot Disguises Itself As A Ball

When the Skynet baseball bot swarms attack, we’ll be throwing [Carl Bugeja] some dirty looks for getting them started. He’s been working on 4B, a little quadruped robot that can transform itself into a sphere almost perfectly.

Before [Carl] was distracted by the wonders of PCB actuators more than a year ago, he started working on this little guy. He finally found some time to get it moving on its own, and the preliminary results look promising to say the least. Inside the 6 cm sphere is a total of 12 servos, 3 for each leg. All of the mechanical parts were 3D printed in nylon on an SLS machine, and the custom PCB has a BLE microcontroller module, an IMU and IR proximity sensors onboard. Everything is open source with all the files available on the Hackaday.io project page.

The microcontroller runs a full inverse kinematic model, so only the desired tip and base coordinate for each leg is input and the servo angles are automatically calculated. Ultimately [Carl] aims to have the robot both walking and rolling controllably. So far he’s achieved some degree of success in both, but it still needs some work (see the videos below. We’re eager to see what the future holds for this delightfully creepy bot.

Walking robots are always an interesting challenge. For more of our future overlords, check out this adorable little cat and this truly terrifying strandbeest.

Super Easy Small Robot Wheels

Anyone who has delved into DIY wheels knows that they are a trickier than it may seem, especially if the wheels aren’t just for show and need to provide things like decent traction and durability. 3D printers have helped a lot, but they’re not a cure-all.

Check out how [Robert K.] makes wheels from segments of automotive silicone hose, which are constructed with fibers embedded within them for durability and structure. Not only are these hoses easily sourced, but the silicone makes a great wheel surface and the hoses themselves are highly durable. He uses a 3D printed jig to cut a slice of hose that press-fits perfectly onto a 3D printed hub. [Robert] finds that a 28 mm hose pulled over a 35 mm diameter wheel is a perfect fit.

These wheels are for a Beetleweight class combat robot, which are limited to three pounds (1.36 kg) or less. You can see some video of [Robert]’s previous Beetleweight robot named ‘Bourbon’, and we have featured what goes into the even-smaller Antweight class (one pound or less) in the past.

You May Trust Driverless Cars, But Do You Trust Driverless Barbers?

Although it is getting more common to have self-driving cars on the road, we have to admit we are still a bit uneasy. After all, we know first hand how hard it is to think of every case and how unreliable things can be. But what about having your hair cut by a robot? At least a car can have airbags and automatically stop at any sign of trouble. But letting a robot hold a sharp instrument up to your head? That’s what Buzz Robotics wants to do and they are starting with a neck trim that you can see in the video below.

Honestly, since the trimmers are probably not that dangerous, we feel a little better. But the fact that the screen says “Calibrated Bad” doesn’t install confidence. While the robobarber might not be able to cut your head off, it could certainly ruin your coiffure.

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ArrBot Is A Fast Way To Get Out Standing In A New Field Of Robotics

[Junglist] correctly points out that agricultural robotics is fast on its way to being the next big thing (TM) and presents his easy to build ArrBot platform so others can get hacking fast. 

The frame is built out of the same brackets and aluminum tubing used to add handrails to stairwells on buildings. Not only is this a fast way to do it, the set-up can be guaranteed to be sturdy since hand rails are often literally standing between life and death. The high ground clearance allows for all sorts of sensors and devices to be mounted while still being able to clear the plants below. 

For motion hub motors driven by an ODrive were re-purposed for the task. He explored turning the wheels as well, but it seems like  differential steer and casters works well for this set-up. ROS on an Nividia Jetson runs the show and deals with the various sensors such as a stereoscopic camera and IMU.

We’re excited to see what hacks people come up with as research in this area grows. (Tee-hee!) For example, [Junglist] wants to see the effect of simply running a UV light over a field rather than spraying with pesticides or fungicides would have.

An Open Assistive Robotic Arm To Help People Feed Themselves

Despite being otherwise capable, not everyone is able to feed themselves. [Julien]’s robot arm project aims to bring this crucial independence back to those people. Assistive devices in this space do exist, but as always they’re prohibitively expensive and the approval process is a nightmare. The development of the arm started by working closely with people who needed it at a local hospital. We note with approval, quite a few cardboard mock-ups to get the size and shape right before more formal work was done in CAD.

The robot arm only has to support a very light payload so its construction can be quite light. A frame of steel rods or plywood is all that’s required. We like how the motion is transferred from stepper motors to the joints of the arm by generously sized timing belts allowing the weight of the arm to remain towards the base. The team behind the project has gotten it to a point, but they’re hoping it will inspire community involvement as they move forward with it.

It’s worth noting, this is not the first assistive eating aid we’ve covered.