Author: Danie Conradie

431 Articles

Animatronic Puppetry Controller Skips Joystick Or Keyboard

September 4, 2021 by 2 Comments

One of the major challenges of animatronics is creating natural looking motion. You can build something with an actuator for every possible degree of freedom, but it will still be disappointing if you are unable to control it to smoothly play the part. [Mr. Volt] has developed a passion for animatronic projects, but found programming them tedious, and manual control with keyboard or controller difficult to do right. As an alternative, he is building Waldo, an electronic puppetry controller.

The Waldo rig is being developed in conjunction with [Mr. Volt]’s build of Wheatley, the talkative ball-shaped robot from the Portal 2 game. The puppetry rig consists of a series of rings for [Mr Volt]’s hand, with the position of each being read by angle sensors. This allows him to control Wheatley’s orientation of the body and eyeball, eyelids, and handles. Wheatley and Waldo both still need a few refinements, but we look forward to seeing the finished project in action.

The Portal games have inspired several featured projects, including GLaDOS, the turrets, and of course more Wheatly builds.

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Smooth Servo Motion For Lifelike Animatronics

September 3, 2021 by 10 Comments

Building an animatronic robot is one thing, but animating it in a lifelike fashion is a completely different challenge. Hobby servos are cheap and popular for animatronics, but just letting it move at max speed isn’t particularly lifelike. In the video after the break, [James Bruton] demonstrates how to achieve natural motion with a simple animatronic head and a few extra lines of code.

Very little natural body movement happens at a constant speed, it’s always accelerating or decelerating. When we move our heads to look at something around us, our neck muscles accelerate our head sharply in the chosen direction and then slows down gradually as it reaches its endpoint. To do this in Arduino/C code, a new intermediate position for the servo is specified for each main loop until it reaches the final position. The intermediate value is the sum of 95% of the current position, and 5% of the target position. This gives the effect of the natural motion described above. The ratios can be changed to suit the desired speed.

The delay function is usually one of the first timing mechanisms that new Arduino programmers learn about, but it’s not suited for this application, especially when you’re controlling multiple servos simultaneously. Instead, the millis function is used to keep track of the system clock in the main loop, which fires the position update commands at the specified intervals. Adafruit wrote an excellent tutorial on this method of multitasking, which [James] based his code on. Of course, this should be old news to anyone who has been doing embedded programming for a while, but it’s an excellent introduction for newcomers.

Like most of [James]’s projects, all the code and CAD files are open source and available on GitHub. His projects make regular appearances here on Hackaday, like his mono-wheel balancing robot and mechanically multiplexed flip-dot display.

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Coaxcopter To Carry Man

September 3, 2021 by 14 Comments

One of the major perks of all the affordable flight controllers and motors available from the hobby market is that you can really experiment with some crazy aircraft designs. [amazingdiyprojects] is experimenting with a coaxial helicopter design, with the goal off possibly using for a manned version in the future. (Video link, embedded below.)

The aircraft uses a pair of coaxial counter-rotating motors with large propellers, with several redundant control surfaces below the propellers. One of the theoretical advantages of this arrangement, compared to the more conventional quadcopter type designs, is redundancy. While a quadcopter will start tumbling when a single motor fails, this design will still be able to descend safely with just one motor.

It is also not dependent on the main motors for yaw, pitch and roll control. In multirotors, the motors need to keep a significant amount of the motor’s available power in reserve to increase torque at a moment’s notice for attitude control. This craft can use all the available thrust from the motors for lift, since control is provided by the control surfaces. There are five sets of redundant control surfaces below the propellers, each set connected to a separate flight controller.

Another advantage of this design is efficient for a given footprint, since one large propeller will always be more efficient than multiple smaller propellers. One of the goals for [amazingdiyprojects] is to fit the full size craft in a shipping container or on a trailer for transport without dissasembly.

[amazingdiyprojects] has built manned drones before, using both electric motors and internal combustion engines. And don’t miss the most gonzo wind tunnel ever at 7:00 in the video below. Continue reading “Coaxcopter To Carry Man” →

Extending bicycles can lift it's rider a meter into the air on four pneumatic pistons

Extending Bicycle Will Let You Stand Out Above The Crowd

September 2, 2021 by 10 Comments

Some bicycles are built primarily for practicality, while others are more focused on novel looks. [Make It Extreme]’s latest project, the extending bicycle, falls squarely in the latter category.

Built around four custom-machined pneumatic pistons, this electric bike can lift the rider about a meter into the air with the flick of a switch. The front pair forms the bicycle’s forks, while the rear pair is mounted between the frame and swingarm. A small onboard compressor is used to charge a pair of modified fire extinguishers, which feed the pistons via pneumatic valves mounted on the handlebars. The wheels and brakes were scavenged from an old scooter. Since the length between the crankset and rear wheel never changes, there is no need to struggle with chain tensioners as the ride height changes.

While we would hate to face-plant from that height, it certainly looks like a fun ride and conversation starter. This is the case for many of [Make It Extreme]’s projects, like a ridable tank track and monowheel motorcycle.

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One Wood Ring To Rule Them All

August 31, 2021 by 3 Comments

[Olivier Gomis] did not have access to the fires of Mount Doom to forge a large replica of the One Ring, so he had to settle for patience, maple, and a wood lathe. It does have the added convenience of not needing to fire to expose its true nature, just angry pixies from a wall socket.

[Olivier] made the ring in separate inner and outer sections from 72 blocks of maple. The blocks were glued together in 12-sided rings, and stacked in layers to achieve the desired width. The surfaces were cut smooth and thinned out on a wood lathe, and an internal channel was created for LED strips. The Black Speech was cut through the walls of both the inner and outer surfaces using a manual router. Using the ring itself as a former, he made a wooden base for the router to allow it to slide across the surface without wobbling.

The inside wall was cut into sections and glued into a recess in the external portion. The inscriptions were covered with a maple veneer, which still allows it to be visible when the internal LEDs are switched on. The wiring runs from the base of the stand through an S-shaped stem that was made from layers of veneer clamped in a former. A total of 53 hours of painstaking effort went into this work of art, but the end product would make any hardcore Lord of the Rings fan envious.

For more LOTR-themed hacks, check out the secret door to the Mines of Moria secret door, and a sword that glow blue in the presence of unsecured WiFi.

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Small Footprint Scara Laser Engraver Has Massive Build Area

August 31, 2021 by 22 Comments

One of the limitations of the conventional Cartesian CNC platforms is that the working area will usually be smaller than its footprint. SCARA arms are one of the options to get around this, as demonstrated by [How To Mechatronics], with his SCARA laser engraver.

This robot arm is modified from the original build we featured a while back, which had a gripper mounted. It uses mainly standard 3D printer components with 3D printed frame parts. The arms lengths are sized to fold over the base and take up little table horizontal space when not in use. It can work in a large semi-circular area around itself, and if a proper locating and homing method is implemented, it can be moved around and engrave a large area section by section.

One of the challenges of SCARA arms is rigidity. As the cantilevered arm extends, it tends to lean over under its weight. In [How To Mechatronics]’s case, it showed up as skewed engravings, which he managed to mitigate to some degree in the Marlin firmware.

Another possible solution is to reduce the weight of the arms by moving the motors to the base, as was done with the Pybot or dual-arm SCARA printers like the RepRap Morgan.

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Making High Quality Copies Of Existing Parts Using A Silicone Mold

August 26, 2021 by 4 Comments

3D printing has made it incredibly easy to produce small runs of plastic parts, but getting rid of the 3D printed look can be tricky and time-consuming. When you need a smooth and polished finish, or you want to make exact copies of an existing injection molded part, casting resin parts in silicone molds is an excellent option. [Eric Strebel] has plenty of experience with the process, and demonstrates it in detail while creating copies of violin chin rests that are no longer in production. It’s an interesting application, where 3D-printed layer lines are not just an aesthetic issue, but something that would irritate the user’s skin if present.

Creating silicone molds requires a bit of forethought about the mold design. You want to select the split line to make it as easy as possible to remove the finished parts, while also placing the resin pouring sprue and vents to prevent air bubbles from getting trapped in the mold. In [Erics] case, it’s impossible to use a simple planar split line, so he mounts the master part on a block of wood and uses cardboard and modeling clay to create a volume where the second side of the mold will protrude in the first side. It’s important to note that sulfur-free clay must be used, otherwise the silicone might not cure.

One side of the silicon mold is cast first, and after curing it is placed back in the mold box with the master part to allow casting the other side of the mold. At this point [Eric] super glues the sprue-former and vent rods to the master parts before molding the second side. A release agent consisting of petroleum jelly and naphtha is added wherever the two sides of the mold will touch, to prevent them from sticking together.

Bubbles are your enemy while resin casting, so ideally you need a vacuum chamber to degas the silicone and resin before casting, and a pressure chamber to allow the resin part to cure. While pouring the silicone for the molds, the mold box is placed on a vibration table to allow any bubbles to rise to the surface. While the entire mold-making and molding process is time-consuming, the copied parts are almost indistinguishable from the original.

[Eric] has also shown us how to make much larger silicone molds in the past. If you find yourself making lots of different-sized mold boxes, it might be worth building an adjustable mold box.

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