Personal UAV’s are becoming ubiquitous these days, but there is still much room for improvement. Researchers at [Modlab] understand this, and they’ve come up with a very unique method of controlling pitch, yaw, and roll for a coaxial ‘copter using only the two drive motors.
In order to control all of these variables with only two motors, you generally need a mechanism that adjusts the pitch of the propeller blades. Usually this is done by mounting a couple of tiny servos to the ‘copter. The servos are hooked up to the propellers with mechanical linkages so the pitch of the propellers can be adjusted on the fly. This works fine but it’s costly, complicated, and adds weight to the vehicle.
[Modlab’s] system does away with the linkages and extra servos. They are able to control the pitch of their propellers using just the two drive motors. The propellers are connected to the motors using a custom 3D printed rotor hub. This hub is specifically designed to couple blade lead-and-lag oscillations to a change in blade pitch. Rather than drive the motors with a constant amount of torque, [Modlab] adds a sinusoidal component in phase with the current speed of the motor. This allows the system to adjust the pitch of the blades multiple times per rotation, even at these high speeds.
Be sure to watch the demonstration video below. Continue reading “UAV Coaxial Copter Uses Unique Drive Mechanism”
[JC] built himself a hexapod based on a project he found on the Internet. It worked fairly well, but was mechanically weak and prone to breakage. He set out to improve the design and came up with the unit seen above. It uses three servo motors to control the six legs, and walks quite well as seen in the quick clip after the break. It’s not quite as agile as the little acrobatic six-legger we saw yesterday, but the movement is quite pleasing and it’s capable of moving forward, backward, and turning. [JC’s] post is four pages in all so don’t forget to seek out his links for the construction, linkage, and servo control pages to find concept drawings, cad designs, and his thoughts on the process.
Continue reading “Improving a hexapod design”
We like a good flight simulator but often find the available control schemes lacking. [Roland] not only builds his own controls, but creates full cockpits that add physical motion to the mix. He completed his third generation cockpit last year. It’s pictured above as well as in video after the break. That design uses a belt system to move the tricked out cockpit.
Now he’s started work on prototypes for generation IV. This time he’s using three Sarrus linkages to replace the belt system. We saw these linkages yesterday in an extruder prototype and if they can handle the load they should work well for this application. Video of the prototype is embedded after the break but be warned, the lewd thrusting motions are not for the faint-of-heart. Continue reading “Four generations of motion simulators”