OKE Precision Winch "Reel and Rotate" Technology

Engineering Ground station
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Universal Kite Controller: Anti Tangling; Continuous Looping by OKE.LLC

Hello everyone, I would like to introduce you to OKE.LLC.

I’ve managed to solve a key mechanical issue in wind energy systems: effectively reeling lines while allowing them to rotate around each other to prevent tangling. This isn’t a trivial problem by any means. Tangling can result in substantial downtime, timestaking repairs, and a notable decrease in energy generation, So, the solution that I’ve developed is a significant contribution to the field.

The company is not a renewable energy company per se, rather, I focus on manufacturing and enhancing critical hardware for wind energy - specifically high-speed/high-torque winches and our proprietary anti-tangling technology.

Notable functions of the OKE (Orbital Kite Engine) are as follows:

Supreme Control Over Every Line: The kite controller offers distinct and simultaneous control over three reels, meaning you have control over various inputs like steering, depower, lifter, and more.

Multiple Line Ports: Six line ports are available for situations where reels need to carry more than one line (of the same length). This is useful, for example, when flying a daisy arrangement that can extend the length of each peripheral line for increasing pitch or depowering, or for multiple Flygens operated by one groundgen without breaking Makani’s patents.

Anti-Tangling Rotating Winches: The winches orbit with the kite while managing the radius of the kite loops indefinitely without tangling. There’s no need to rotate in the opposite direction or count rotations. This mechanical solution simplifies programming and control, and with no mechanical restrictions, the kite can fly its most natural path.

High Capacity Reels: The current prototype features reels with a capacity of 600 feet/182 meters.

High Speed/High Torque, Hybrid Drivetrain: With gear reductions ranging from 1:1 to 30:1, this unique “Continuously Variable Transmission” style system is designed to quickly snatch slack line. When met with resistance, it adds tremendous torque as it slows. The drivetrain’s hybrid nature allows it to handle any speed between 1:1 and 30:1 (unlike a traditional CVT with a 1:1 - 6:1 range) and seamlessly flow through gears. This enables dynamic winch control in terms of torque, speed, and regen capabilities.

Lightweight and Powerful: With no control pod and additional weight, the system uses unobstructed, light tethers, leading to faster kites and more power. Power is more evenly distributed down the line, leading to increased kite height due to a higher flying angle, which in turn results in larger wind windows and more powerful kites.

Versatile Applications: The system’s versatility means it can be used by any Airborne Wind Energy System or control strategy that manages single or multiple lines. It is suitable for use in cross wind, Yo-Yo, Carousel, Daisy’s, Flygen, multiple Flygen, mastless boat, land yachts, multiple Flygens, and more.

The hardware I’ve developed finds its applications beyond just wind energy generation; it’s also invaluable in towing boats/marine operations. This connection may not be immediately obvious, but the mechanical principles of handling lines under high-tension loads and preventing tangling are shared challenges in these sectors.

In essence, at OKE.LLC, tries to place itself at the intersection of the marine and wind energy industries, providing technical solutions that deliver value to both.

More to come

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During the descent of the kite as it was rotating, its two lines rotated “each other” (the video shows it), the length of the two lines being fixed. A series of rotations in the other direction would end up separating the 2 lines. But perhaps your device would allow continuous looping without excess of “rotating each other”?

I’d noticed that when the kite descended while turning, it seemed to be able to stabilize above the ground (ground effect?).

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Indeed, the length of the lines can be either static or dynamic in length all while preserving the ability to reel in and out line.

No need to fly the kite in the opposite direction to correct twisted lines. This means the winch can conduct constant loops. And modulate the size of the loops.

To answer your hypothesis, here’s what I think

As the kite descends, it enters a stronger region of the wind window, If I were to guess, I would suspect that is the cause for it to stabilize. Which is very news. Loops naturally dive deeper in the wind window, much deeper than figure 8’s as the bottom portion of the loop is directly downwind as opposed to figure 8 geometry

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I was happy to see your experiments, Pierre. it’s nice to corroborate our empirical claims.

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Indeed, but if you look at the video between 26:00 and 33:00, when the kite is descending while rotating, the traction goes progressively from 5 kg (in the top) to 3 kg (close to the ground), probably because the wind is stronger in the top.

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This might also be because as the lines twist, the kite progressively becomes less effective. The kite begins to fold in on itself as the space in between the tethers closes during twisting.

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We can imagine a kite with two lines (like the one I used), in reeling (= yo-yo = pumping) mode, turning passively during the descent in reel-out power phase (unlike a usual kite in yo-yo mode whose power phase is during its ascending), then rising quickly but without rotating when your kite controller has finished separating the 2 lines, still in reel-out power phase. Then the recovery reel-in phase occurs when the kite is pulled from the top of the top to the top before descending again while rotating in a new cycle.

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Im sorry, I didnt understand quite at the beginning, Yes, it sounds like the OKE can perform those maneuvers given that it has independent control over 3 lines. You could add an additional Depower line into the mix if you were flying a 3 line kite.

Moreover, the controller has the unique capability to apply positive tension to one control line while simultaneously creating absolute slack in the others. This allows the kite to “slip” with minimal resistance during reel in, before snapping back to its pre-set line lengths.

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I dont understand what this device should do. Could you please ELI5?

I have a feeling that any such equipment should first be developed for a specific application. Otherwise you would be sure to miss some important requirements. Eg; Im wondering if that bending radius is suitable for AWE, at least any such where tether lengths are varying during production

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A sketch can perhaps help, assuming it is for a two line kite:

Reeling (= pumping = yo-yo) mode by using low radius loops
Reeling (= pumping = yo-yo) mode by using low radius loops947×847 93.6 KB

Unlike usual yo-yo systems, here the kite generates power by descending passively in low radius loops, and also during a short second phase where the kite rises to the top.

Between the phase 1 and the phase 2, untangling the 2 lines would be useful.

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Funny how words evolve: “Window” came from “Wind Hole” which let you enjoy ventilation (windilation) and visually see outside. But then wind hole becomes “window” so we think we need to add another “wind” to make a “wind window” Maybe we should just stick with “Wind Hole”.
Let’s use it in a sentence: “OMG What a freakin’ Wind-Hole!”

Next word: “Cupboard” - yup it was a board you placed your cup on to hold it. Mayube today we should have a special cupboard for cups - call it a “cup cupboard”.

Next word: “Threshold”
What is it? Well, in the era of dirt floors, people used straw to cover the dirt, like living in a barn. The straw was called “thresh”. So the threshold was a board (like a cup-board) stood up vertically like a dam across the bottom of a doorway, to hold the thresh inside the house. “Thresh Hold”.
OK class dismissed.
(Nice to acknowledge where some of our words come from!)

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@tallakt

Looping is the most natural path for a power kite to harness energy, and @PierreB’s insights align with this. We may even discover that a loop that gets wider as line is paid out is even more advantageous.

On the OKE system, we refer to the “left line” as the “Orbital Line” and the “right line” as the “Tether Line”. When you attach control tethers to each end of a flying wing, the kite starts to turn/rotate towards the line with the most tension. In the OKE arrangement, the Tether line passes through the center of the machine, emitting from the center of the circular front face, while the Orbital and Depower lines emit from the outer edge of the circular face.

You can increase the difference in length between the Orbital and Tether lines to initiate rotation. This difference is maintained while the loop is performed (as the line is reeled out), with the Tether length adjusted as needed to correct the flight path.

Because the relative distances between the control inputs (Orbital, Tether, optional Depower) stay the same, the kite maintains relative performance while line is reeled. In this mode, we can slowly pay out line while looping by simply syncing the winches and rotating them together.

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Nice work and I agree that this is a good idea to work on. I also don’t really understand how this works.

How efficient is it?

It looks like a planetary gear system to me and not a CVT? Can you independently change the gear ratios of all 3 reels and do that continuously (from 1:1 to 1:30) and not in discrete steps?

Those are free to use now IIRC. I’d go for the better solution without worrying too much about patents.

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From my understanding, Makani’s patent involves a “splitter” that flies between two flygens, with the aim of reducing drag. However, the method for reeling in the line beyond the split isn’t clear. Our design could potentially provide a solution to this.

We’ve chosen to use two BLDC motors and a planetary gearset (and deal with the extra programing) to eliminate complicated transmission methods associated with a Continuously Variable Transmission (CVT). This setup also avoids issues related to slipping and hydraulics with CVTs.

We typically operate both the sun motor and the annulus motor at 50% capacity to conserve battery/capacitor power, essentially treating the two motors as one.

This approach offers two key advantages:

  1. It doubles the generating capacity during regen mode.
  2. It allows for extremely quick reeling in of slack (using both motors in co-rotation) and provides low torque for power (torque is limited to the motor with the most torque).

The mechanism is somewhat similar to how a car differential works. In a car, the inputs are the two wheels and the output is the driveshaft, effectively combining power. In our case, the two motors serve as the inputs, combining their power for the output.

This Hybrid Drivetrain primarily controls the orbital line but has has a system of clutches to sync reels.

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OKE LLC was granted a provisional patent for the Orbital Kite Engine

OKE PROVISIONAL PATENT.pdf (678.4 KB)

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Congratulations for your work @ChristianH.
Now kite systems towing a boat, or for kitesurfing (as shown on your video) can more easily fly in loops. The same for FlygenKite .

But for reeling (yo-yo) systems, one or two tethers (perhaps the same two lines?) in alternating reel-in and reel-out (unwinding, winding) phases, must take over to go towards the winch(es) driving the generator(s): perhaps you have solved the specific issue for yo-yo mode? If yes low radius loop control in yo-yo mode will be also able to materialize in a simpler way.

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The OKE precision winch functions similar to a spinning reel. You can power it either with a motor or manually via a crank. It controls three lines independently.

Moreover, the winch has a feature to synchronize the Orbital line reel (left line), the De-power reel (depower line), and the baler. This allows these reels to be locked together while still maintaining their ability to rotate.

This configuration allows the kite or any other load to move freely. Additionally, because the Orbital and Depower lines rotate around the tether line (right line), it helps in compensating for any twists in the system.

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Hello @ChristianH,

My question about a lighter control pod relates to part of your topic, which is “Reel and Rotate”, and could correspond to the other end of the device you described, and which would also apply to Low radius loop.

How do you make a much lighter control pod, bearing in mind that controlling a loop could be simpler (?) than controlling a figure eight? Thank you.

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The Skysails design is robust, yet it comes with certain compromises. Although I can’t pinpoint immediate optimizations regarding assembly, there might be potential in switching parts or upgrading the gearbox. Nonetheless, the overall configuration is excellent for a dedicated AWES.

Using band steering offers a reliable way to control a kite. Rolling the weight of control tethers is generally simpler than pulling them directly, though this method sacrifices agility. One can configure this system for loops, allowing for active modulation of loop radius to counteract altitude loss from consecutive loops. The integration of slews and slip rings is essential to preserve the electrical connection during loops. I’m hesitant about implementing a dedicated RF connection to the pod.

The OKE stands out as a universal kite controller. Its design inherently offers versatility, meeting the needs of various mechanized kite sports with a precision winch capable of managing multiple lines simultaneously.

It’s feasible to configure the OKE to mimic the band’s function on the control pod. However, instead of a band, the OKE would utilize a “reel to reel” system where both reels share a common axis (via clutch). This setup would also accommodate an additional line for depowering with the OKE assembly.

The advantage of the OKE in this case is that it could reel or pull lines in and out as well as treat them as a band for easy control… (band control?)

The OKE can operate autonomously without the need for RF signals and also offers manual control. While the SkySails control pods are mainly designed for AWES, they don’t cater optimally to high-performance kite sailing.

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Perhaps a control pod is not required?

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Though not optimized for agility or performance… the Control Pod works.

Cons of Control Pod:
Added weight/ max altitude loss
Conductive cable(?)
Sluggish controls
No redundancies for RF signal loss

Pros of Control Pod
Possibly less tether drag, the OKE commands 2 or 3 lines (of significantly smaller diameter), but the lines do not have to be conductive

In terms of acrobatics and agility I would really like to see the difference in performance with a control pod and without one…

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