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Found 14 results

  1. We are lucky enough that we have a small band of Whisper Sailors playing around and posting videos and rigging / tuning notes. - @Flying Tiger Whisper is publishing his videos, including some how to rig it, at https://www.youtube.com/channel/UCipkSggLhwNpIpeSGgIMBDA - @flyinggorilla is publishing... videos at https://www.youtube.com/channel/UCwhb6u4A_Hy-c-eJbMLW7bg amazing docs and anecdotes at https://github.com/flyinggorilla/whisper-foiling-catamaran - My own stuff: videos https://www.youtube.com/channel/UCwa0EvPl3EP65GVsM8EqCMA docs (dated now) https://martin-langhoff.github.io/whisper-foiling-catamaran/ ~ ~ ~ Happy to answer questions, discuss Whisper topics here. Now that summer is here, I expect you'll see more videos as we sail, play, capsize and fly...
  2. Finally real success! I got back out there this week with a fully waterproofed servo, an added lidar sensor and a major code overhaul based on Test Flight 1's test data. Observations were: 1) Pitch control is now much better. While I still think the control loops could be better tuned, I am now getting long runs with very good pitch stability and no more porposing as you get with the wand-based systems. In lighter air, I suspect that the lack of paddle / wand drag will allow me to fly more easily as well. 2) Servo waterproofing worked great. 20 knots of wind and lots of spray and crashes and the servo never blinked. This was a big victory and only involved some grease and spray urethane. 3) There is still some servo chatter / oscillation. It is minor and doesn't affect performance much but it is bothering and inefficient. I will comb through the data and see what code changes could be made to maintain the low latency reaction while smoothing the servo reaction. Two and a half hours of good foiling and 5.5MB of data taken. Great day out there and lots more data to pick through! In another few flights it might be time to think about the follow on to this prototype. Lighter, smaller, sleeker and more awesome!
  3. I got out Monday for a first flight for my digital flight control system. Overall it was a big success! The one thing I cut corners on to get out there was fully waterproofing the servo. I felt that the likelihood of a turtle capsize was low (my last one was months ago). Of course, what did I do after 90 minutes out there? Turtled the boat and killed the servo--HAHA! But still a great day with lots of learning and successes: 1) Being able to "arm" the system at the press of a button was a major convenience. When the system is "not armed" it is as if the wand is all the way up and in non-foiling mode. In the armed state, the boat will try to fly at the desired altitude set point. Sailing off the dock and around the marina where you really don't want to foil is super easy. No more swimming out to the spirit to adjust ride height! Furthermore, adjusting altitude and other parameters was easy with the key fob switch. The LCD could have been easier to read, but it worked. 2) The electronics enclosure really is waterproof! After a tough turtle recovery, the electronics survived DRY after 3-4 minutes submerged in about 12 inches of water! 3) The servo is NOT as waterproof. After the same submersion the servo continued to work for another 5-10 minutes before water ingress fried the circuit board in the servo. Thankfully these are $40 parts and available with 2-day shipping. There are lots of tutorials on how to waterproof servos. I plan on doing so prior to my next flight test. 4) Control loops need tuning. Things worked out on the water but the control loops felt like they were always behind where they should have been. I can see it in my data collected and it can be seen in the videos (below). After an hour of tuning with the wireless key fob, I was starting to get close to the performance I wanted. Thinking more about the wand if it were a PID controller (Proportional, Integral, Differential), it will have a P = infinity and I = D = 0 (yes, I know I'm ignoring the mode where the wand is just fluttering on top of the water, but let's keep this simple folks). That leads me to believe, I will need to really crank up my P constant (currently set at 9.0). I think the I and D constants will be helpful for improving performance beyond the wand, but I'd like to duplicate what I have first. 5) Epic data collection! After 90 minutes of floating and foiling I have 5MB of CSV data on heel angle, pitch angle, altitude, smoothing params, PID params, acceleration in X, Y and Z axes, battery cell voltages, etc. This data will help me tune control loops on shore. My first guess at constants was made by watching our UFO videos frame-by-frame and estimating elevation and rise/sink rates. My new data is at 20ms resolution and will give me a much better shot at getting things very close on shore before I head out next! 6) Battery life will NOT be an issue. After 1.5 hours of foiling I had better than 85% of the battery left. On prototype #2 I will definitely go with a smaller battery to cut costs and reduce size / weight). Either way, I have hard numbers on cell voltages vs. time and will accurately be able to calculate how much battery capacity will give me how much time on the water. 7) I need a hard-reset switch on the boat. The ultrasonic altimeter I am using is a cheap one from a car bumper. Occasionally it gets noisy and needs a reset. Having a way to do a full power cycle on the water short of taking the lid off the enclosure would make resetting the altimeter easier. In the long run, I will be looking for a higher reliability part for prototype 2.
  4. Hey team, just shot a quick video on my solution to adjusting altitude and some of the other prototype variables. First flight is TODAY!
  5. Electronics module and servo now fully mounted on spirit and actuating the flap with torque to spare! First flight in mid June is on track! Last steps are some linkage adjustments and test tank time (in my hot tub)!
  6. See the linkage working with the servo and altimeter to control the bell cranks and foil flap. First flight should be sometime in June!
  7. Another update from the land of digital flight control systems! Integration I now have all sensors talking to the Grand Central board and the algorithms (PID loop, ultrasonic sensor filter and smoothing, etc.) performing as designed. The wireless remote is also working and allowing the user to adjust PID Parameters, Altitude Setpoint, and Smoothing coefficients. The LCD is putting out status messages and feedback when the user is changing parameters. I am also collecting all the data from accelerometers, gyros, ultrasonic sensor, battery cell voltages, etc. and storing it to an SD card (sample data and charts below). The data gathering ability will be a major feature in itself. We will really get to be data-driven about what sorts of tunings make the boat go fast. For example, comparing nose up vs. nose down pitch angle, fastest ride height for different points of sail, etc. A simple battery management system is also now working indicating battery State of Charge as well as cutting off power to the servo when the battery gets too low to avoid damage to the cells. Last, the integrated PCB and battery have been installed into the waterproof housing and a gland has been installed to allow for a waterproof cable passthrough. I am planning on doing some more testing of the integrated system in the “test tank” (aka my hot tub with the jets going). I may throw my 5-year-old in there and tell him to do some cannonballs. The goal is to ensure that the ultrasonic sensor is reading turbulent water well and that the default IIR smoothing filter settings are correct. In particular, the smoothing needs to be set to smooth water ripple and wake without paying too bit a price in lag. The smoothing coefficient is tunable using the wireless remote so the goal here is just to get the default setting close. Final tuning can be done out on the water. A lot of progress for 6 weeks. Data Analysis The other fun side-project is analyzing data from all of the sensors and graphing things. I am able to gather data every 10ms which gives very good granularity. Currently I am collecting the following data fields: 1) Raw ultrasonic range sensor altitude (cm) 2) Filtered ultrasonic range sensor altitude (cm) 3) Smoothed ultrasonic range sensor altitude (cm) 4) Vertical acceleration (m / s*s) 5) Heel Angle (degrees) 6) Roll Angle (degrees) 7) Commanded servo position (0-100%)* 8) Battery cell 1 voltage (Volts) 9) Battery cell 2 voltage (Volts) *Rotary servo position (0-180 degrees) is converted in software to linear servo position using the proper trigonometric functions. In the code, the servo is commanded between zero- and one-hundred percent representing percent of total linear throw. I have attached some screenshots from excel where you can see the value of visualizing the data and how different filtering techniques and filter combinations affect altitude readings. Great to see that the outlier rejection (orange line) and IIR smoothing (gray line) are doing what they are supposed to do! I am also curious as to how fast the battery drains during foiling and monitoring cell voltages should give me a good picture of battery life. Mounting Plate I have also purchased Clickbond studs which will be bonded to the sprit. The mounting plate will then be screwed on to the Clickbond studs. The mounting plate still needs to be designed but it should be pretty straight forward. It will hold the enclosure, and mount the waterproof servo and ultrasonic range sensor. I am currently experimenting with perforated aluminum as it is strong and easy to work. Linkage My last step is designing the linkage to mate the servo to the existing flap control rod. Thankfully, there is already a bell crank on the sprit. I will not use the existing bell crank because it is not shaped correctly for my purposes, but I will use its pivot pin. I have to do the calculations to determine the correct length of each side of the bell crank to ensure the mechanical advantage and throw are correct. Additionally, I need to measure the total actuation length of the flap. Time to get out the calipers. Until next time, stay flying.....
  8. Another quick update, A productive weekend ended up with an IMU (BNO055) and a waterproof sonar range sensor (JSN-SR04T) being integrated to my Arduino Mega board. Both are yielding good data and easy to work with. I also am able to write commands successfully to a spare servo I from an RC Tricopter. I am still in the process of selecting the correct servo and identifying the correct attachment point(s) for the servo to flap linkage (please see and comment on servo math below). Additionally, I now have a PID library running giving servo commands based on the measured elevation. Tuning the loop gains will take some tweaking and I am beginning to realize a few buttons and a display of some sort may be necessary. I am trying to avoid scope creep but tuning control loops will most certainly need to be done on the water and doing so on a laptop will not be possible. More fun to come on UX... Lastly, it's time to think about packaging and power. The whole system runs on 5V and would be easy to power off of a set of AA or C cells. Eventually a lithium battery would work well and be rechargeable. I may need to add a power distribution board as the Arduino Mega won't provide enough current for the servo I am guessing. We'll see once the servo is selected. Servo Math Section Speaking of servos, my thinking here is to calculate how much torque is being imparted by the wand and using that as a minimum value required for servo torque. Being conservative my math is as follows: Calculate force on paddle: F = ma from Newton Finding a: Paddle will push flap down at minimum boat speed of about 3 knots or 1.55 m/s -- below that boat speed the flap rebound spring overwhelms the paddle drag. Therefore paddle must accelerate oncoming water from 0 m/s to 1.55 m/s. I am going to assume that this acceleration takes place over the course of 0.2 seconds. I have no scientific basis for this duration of acceleration. In reality this is probably a very complex fluid dynamics problem, but I think 0.2 seconds is a safe and conservative number. Therefore a = (1.55 m / s) / 0.2s = 7.75 m / s^2 Finding m: The paddle is around 4 square inches (~2 x 2 inches). (The wand also provides some drag that we will ignore for simplicity -- hopefully this isn't fatal =) Assuming that the amount of water accelerated from 0 knots to 3 knots is 4 square inches and 1 inch deep (yes another assumption), we have a total volume of water decelerated of 4 cubic inches or 65.5 cm^3 or 6.55e-5 m^3. The density of luke warm seawater is nominally 1027 kg / m^3. Therefore m = 6.55e-5 m^3 * 1027 kg / m^3 = 0.06726kg Finding F: Putting it all together total minimum force on the paddle to push the flap down is: F = ma = 0.06726 kg * (7.75 m / s^2) = 0.52 Newtons To be clear, this is the minimum force it takes to push the flap down when traveling slowly. As speed increases, it will take more force to actuate the wing as the speed of the water rushing by the wing is faster and will increase resistance to movement. Not to fear however, we can use the same approach to calculate the torque imparted on the wing by the paddle at higher speeds by varying a. At 18 knots (about as fast as my GPS has ever recorded me traveling) and assuming acceleration takes place over 0.2 s, our formula becomes F = ma = 0.06726 kg * 46.3 m / s^2 = 3.1 Newtons 18 knots = 9.26 m / s ; (9.26 m / s) / (0.2s) = 46.3 m / s^2 Finding Torque: Putting it all together to get torque, I assume that we are operating on the end of a 1m arm (our wand length). Therefore our torque values would be between 0.52 N-m and 3.1 N-m. A few caveats -- I made a lot of assumptions here and tried to be conservative. I also notice that at high foiling speeds (18 knots) the paddle depresses the flap with extreme ease indicating that while it imparts 3.1 N-m, a far smaller value would be sufficient. The last consideration comes with how to mount the servo and how many meters of moment arm we will use. I am thinking the servo will be mounted close to the fulcrum therefore our moment arm will likely be 0.2 m or similar. Therefore torque will need to increase by a factor of 5 to deal with the fact we only have a fifth the lever arm as the paddle. With all this math out of the way, I want to say that I am not a fluid dynamics or mechanics expert. I intend to take some empirical measurements next time I'm out foiling to verify my math. Please check my work and shoot holes in it wherever possible.
  9. Time for another blog installment of the Digital Flight Control System for my UFO. I have been busy at work on the project and making good progress toward a first flight in early 2020! Also attached is an updated block diagram with details on various subjects below: Data Logging: In my last blog post I mentioned that we needed some sort of data logging to really get into the meat of how well our control and filter algorithms are working. Post processing data after getting off the water will also allow us to see if there is data being generated by sensors that could improve control. For example, I received a suggestion that I take vertical acceleration from the IMU into consideration and use it to derive vertical position. This vertical position would then be fed into a Kalman filter along with the ultrasonic range sensor's vertical position measurements to determine a better estimate for boat altitude. Logging and crunching data after getting off the water would allow us to take these types of ideas into consideration easily. Datalogging would also greatly improve troubleshooting of all types. To this end, I have added an 8GB micro SD card to the design as well as written some simple code to log data to a CSV file for post processing. My current code logs speed (GPS), acceleration (XYZ axes), attitude (XYZ planes), and servo control input. Any other thoughts on datalogger inputs? PID Loop Tuning: It has also occurred to me that tuning PID loops while on the water will not be possible with a laptop. As such, I have integrated a wireless, 4-button, key fob (in a waterproof bag), a wireless receiver and an LCD screen. This will allow for wireless adjustment of PID constants and LCD feedback to the user. This setup should allow for easy adjustment while out on the water between foiling runs. The enclosure chosen also has a clear plastic top to make reading the LCD screen possible. Mounting, Wiring and Power Distribution: The Arduino board I am using only has so many pin outputs for 3.3V and 5V. While my sensors easily fall within the max current output of the board, I am short on pin space. I also have a 3D model of the enclosure that requires at least one mounting plate made from plastic / metal / fiberglass / FR-4. It occurred to me that rather than mess with mounting plates and a wiring rat's nest, I should just burn a simple PCB to handle mounting and power distribution. This PCB may also contain some custom circuitry--we'll see. The PCB will minimize the wiring mess and be a mounting plate in one shot. Many PCB shops will burn custom sized, one-off boards for ~$150. It's probably a small price to pay for much better reliability and maintainability (not to mention the time saved on creating a mounting plate(s) and hand wiring all of the modules). Enclosure: Now that I have selected a battery (2S LiFePo, 8000mAh) and all other components, I created a 3D CAD model of how the boards will lay into an enclosure. It appears that a 4x6 inch case will fit everything we need to hold the system (see photo of selected case). This enclosure will mount onto a mounting plate (probably custom fiberglass or carbon fiber) that will bolt on to click bond studs bonded to the spirit. The servo and ultra sonic sensors (both waterproof) will live outside of the case and be mounted to features on the mounting plate. This section of the design is the most open at the moment and will certainly require more CAD work. That's all for now. Comments are welcome!
  10. Schakel

    This is Wing Surfing

    - "This is Wing Surfing". The tittle of this clip says it all. The rider is Philippe Caneri with a Horue foilboard and a Duotone wingfoil.
  11. Ok team, here goes my first blog post. My goal here is to build a Digital Flight Control System (DFCS) for my UFO using a sonar range sensor as opposed to the wand. The design needs to completely mimic the performance of the wand system currently in the boat. The system needs to be fully removable to allow for One Design Racing if desired. A few design guidelines... Improvements to current control system: 1) Sensing wave terrain out ahead of the boat 2) Not engaging the mainfoil flap until the boatspeed hits 7 knots to reduce drag while floating 3) Toggle settings for upwind vs. downwind (maybe a button press?) 4) Data acquisition 5) Auto rear foil rake adjustment (this is a maybe feature, this would be lots of extra hardware for limited improvement) Questions to answer: 1) Do I need a GPS to get good boat speed or is the accel, gyro, magnetometer IMS good enough? 2) How and where will I couple the servo to the flap control push rod 3) How big a challenge will marinization be? Is enough to buy waterproof parts and a waterproof box? 4) Is it useful to have more than two sonar sensors to create an accurate map of oncoming wave motion? Does wave motion traveling orthogonal to the direction of the boat matter? Or are waves going so slow compared to the speed of the boat that it doesn't matter? Design Philosophy: I will endeavour to use parts that have excellent tutorials available online. I will be concerned about the cost of my time even when it costs a bit more money to buy parts that are easier to integrate. Basic Block Diagram Below: https://drive.google.com/open?id=1fPYXJLlrcZufAwTNtmjy9HG_BbAYtpas
  12. flyinggorilla

    A-Class foiling sailors

    Hi A-Class foilers, I start this thread to have a forum for some basic how-to exchange on foiling A-Class catamarans. I am proud new owner of a DNA F1x catamaran (for single handed sailing) and also sail a Whisper catamaran (works best with crew) for the third season. I am a weekend recreational club-sailor, who loves cool technology and nature at the same time. However, I still have to figure out if and when there is ever enough time to prep and sail the first club regatta. Hence you will find my priorities more on how to mount a gopro, rather then regatta starting-line tactics ;-) Just to get this thread kicked-off, here is a video from my first time sailing with the DNA F1x. I have to say that I was very pleased with the smooth and easy boat handling, the clean deck, the powerful boomless sail, and the stable flight in little winds. And of course the speed. I hit 20kts boat speed on my first day at low winds (18kts speed were captured on gopro) - and I am still at the beginning of learning the boat handling and trimming. cool! FG
  13. Sea trials were supposed to take place this past July, no news from the company. Any insight out there?
  14. scherersailing

    Quant23 Foiling OD Racing

    Something about us swiss... We like to race fast boats on our lakes! (Photos from talented Anja Stöckli) Check Facebook for more pictures and check out the Class...