How to Prevent Trembling Hands from Stopping You Flying
John from Discover RC has a fantastic catch phrase which is "Never Stop the RC!". I love his youtube channel and I completely agree. We should never stop the RC. However what if health issues stop the RC for you? I have had a tremor in my hands since my mid 20's. As I get older the tremor gets slowly worse. When it began to be an issue with my RC flying I sought medical help and a beta blocker kept the shakes at bay for many years. When the shakes became a problem again I switched to using a transmitter tray and that worked nicely for many years. Recently though my tremor reached the point where medication and transmitter trays were not enough and I was forced to stop flying. However I wasn't prepared to give up so I thought about the issue and came up with a solution which is a little out of the box but does seem to solve the problem. I am writing this article because I figure I am not the only person having this issue and so I wanted to get this article out so that perhaps others can benefit.
Devising the Solution
My particular tremor is not the precursor to some horrible disease it is simply something that will continue to get worse with age. In trying to come up with a solution I started by considering the characteristics of my tremor:
- Its worse in my right hand than my left hand.
- Its mostly my fingers that tremble and not my whole hand.
- The more tense I am the worse it gets.
- When my fingers are in certain positions a fairly violent twitching of my whole hand can result.
I reasoned that if I was using my whole hand instead of my forefinger and thumb then the trembling in my fingers would not be a factor. Also if my fingers where not moving individually then an unexpected twitch was not likely. I realized what I needed was a couple of joysticks instead of the small control sticks transmitters use. Initially I thought all I had to do was extend the existing control sticks on my transmitter but then I realized they would be too close together so I came up with the design shown in the image below.
The hole in the bottom friction fits over the existing transmitter control stick and the horizontal piece ensure the sticks are sufficiently spaced apart so as not to collide in inappropriate moments. When fitted to my Transmitter they look as shown in the image below.
I can hold each stick by wrapping my palm and fingers around it. Movement is controlled by my whole hand so even if my fingers are trembling it doesn't impact stick movement. When fitting them it was important to ensure the stick extensions were a tight fit on the transmitter control sticks. If they started rotating while in use it would end very badly for the model in flight. One was a little loose and I fixed that by wrapping some tape tightly around the control stick before fitting the extension. Also I didn't want to damage the transmitter gimbles by pushing down too hard so I unscrewed the top of the control sticks, pushed them into the stick extensions, screwed them back onto the transmitter control sticks, positioned the extensions correctly and then screwed the bottom part of the transmitter control sticks so they were tight against their top parts.
Manipulating the sticks at home indicated that it was all functional. What concerned me was how different would it be to what I was used to? Would I have to learn to fly all over again? I had no idea. The biggest difference was the amount of movement required. I would have to move my hands much further than I previously moved my thumb and forefinger to get the same control input. The diagram below illustrates the issue.
The black lines represent the full range of stick movement. The length of the red arc represents the distance that a normal transmitter control stick would have to move to transition from one extent to the other. The length of the blue arc represents the distance my stick extensions would have to travel to transition from one extent to the other. I was worried that this extra movement would mean retraining my muscle memory and would require me to re-learn how to fly. As things turned out this extra distance proved to be an advantage. I will explain why later.
Stick Extension Construction
I designed and 3D printed my stick extensions and have included the Sketchup and STL files at the end of this article. However I could have just as easily fashioned them from wood as its a pretty simple design so if you do not have access to a 3D printer then use a couple of pieces of broom stick handle and some wood strip to build your stick extensions.
Each extension is printed in two parts and glued together. I used CA glue. Keeping it in two parts made it easier to 3D print.
The Test Procedure
I had no idea how this would work out. For some reason it never occurred to me to try them out in a simulator. I decided to start with quads rather than planes. My reasoning was twofold. Firstly quads require constant use of all four channels (throttle, pitch, roll and yaw) whereas with a plane you don't use the throttle quite as intensely and you can always forget about the rudder. The second reason is quads are much better at surviving collisions with the ground, trees or whatever other objects you manage to collide with. If I really got out of control I could simply cut the throttle and, especially as I would be flying over grass, the most damage incurred would likely only be a couple of props. I picked three different types of quads for my test. Each one, faster and more responsive than the previous one.
The first quad chosen was the ET100. Comparatively docile (I have flown this one indoors), and extremely hardy. If you are looking for a small quad I can highly recommend this one.
The next quad would be my Eachine Lizard 105S. For its size this quad is fast and responsive. I don't think I have it tuned in perfectly via Betaflight because it does not feel totally locked in. Don't misunderstand it flies fine but I find it takes focus to get through race gates without hitting something. For the purposes of this experiment that works as it means lots of control inputs will be required. The main reason I bought it is because its small but has a 720p onboard DVR.
The final quad was my Transtec Frog. Depending upon which review you want to believe it can exceed 100mph or max out at just under 100mph. It feels extremely locked in and precise to fly but, at my skill level anyway, its very easy to over control on the throttle. If my new stick configuration works with this then I am very confident it will work with planes. All the quads were to be flown in air mode. Currently I cannot use my transmitter tray so I planned to fly sitting down with the transmitter in my lap. I am in the process of trying to figure out how to modify my tray so I can still use it. However I didn't want to wait before getting this article out. If there are people out their who fly RC and are struggling with hand tremors then I want to give them this option to try asap.
Test day dawned overcast and with intermittent showers. The silver lining was there was pretty much no wind. I was really nervous. Actually mildly terrified might be a better way of describing how I felt. It wasn't because I was worried about crashing and damaging a quad. I knew that if it didn't work I was going to be devastated to learn my flying days were over. It seemed to take forever to get everything powered up and ready. Seconds felt like hours. I put my little ET100 down on the grass, sat down on my chair, put my transmitter on my lap and slipped on my FPV goggles. I sat looking at the camera view in my goggles for a few seconds. I was dying to know if this was going to work and horrified that it wouldn't all at the same time. I took a deep breath, let it out slowly and pushed the throttle stick forward. The ET100 zoomed up a bit faster than expected because I wasn't sure how far to move the throttle and had over compensated. For a few seconds I was under and over controlling on all four inputs but slowly it started coming together. We had set up two race gates next to each other for practice and as I gained more confidence I headed for the first one. I found I was consistently under controlling on yaw but everything else seemed fine and I shot through the first gate with no problems at all. My fingers were trembling terribly but I was easily able to hold and guide each stick. A slower than I expected 180 degree yaw (still under controlling on yaw) and I was heading for the second gate and shot through dead centre. The rest of the flight proceeded pretty much the same. Towards the end of the flight my tremor had got so bad that the sticks were shaking a small amount. This is where I realised the larger movement required is an advantage because it meant that the tiny movements of the sticks because of the tremor was not impacting control of the quad. They were too small. The larger stick movement was acting as a kind of tremble filter. When I landed I was overcome with relief. My flying days were not over! Or were they? The ET100 is a gentle and relatively easy quad to fly. Time to up the game.
I powered up the Lizard, armed it and took off. Nowhere near as nervous as the first flight but still scared that maybe there were limitations to my solution. I was able to fly through the gates immediately and consistently. My height control was not good as I was over controlling but it slowly improved as did my yaw control. I had four successful flights with the Lizard. By the fourth flight my hands were shaking horribly. You can actually see it in the video linked below when I take my FPV goggles off my face. However I could still fly the Lizard almost as well as before the tremors got so bad. Now I was ready for the final and most significant test. If I could handle the Transtec Frog then I was confident I had succeeded. Not over controlling the throttle on the Frog would be the biggest challenge.
With the Frog powered up and ready and my heart pounding I flicked the arm switch and throttled up and...it was fine. The throttle was an issue but not a major one. I did miss the gates a few times because of poor height control and I hit the gate once because of under yawing but I knew this would come together with practice and it mostly did. I only have two batteries for the Frog and I feel that with a few more flights I would have improved further. In the first part of the video I showed how much my hand is shaking when placing the quad on the ground. The ET100 doesn't have an onboard DVR and I forgot to record using the DVR in my goggles so unfortunately my first flight isn't in the video but I think you will get the idea.
There are a number of things to watch and listen for in the video. As I land the Lizard listen to the motors and you will hear them oscillating as my whole hand is trembling really badly at that point but I still had control of the quad (yes my landings are normally that crappy). Watch for the over corrections on the throttle. I didn't used to bob up and down quite so much but I am hoping that is just getting used to the different control movement. Finally watch the yawing and you will see that I often don't quite yaw enough. As with the throttle I am hoping a little more practice and I'll have that sorted.
I could have given up but that would have left a huge hole in my life. If this had not worked then I would have tried to think of some other solution. I am glad I went through with this and I am extremely happy with the result. I sincerely hope this article can help others with similar issues. Never stop the RC? Of course although in my case I guess it turned out to be "Never give up and never surrender when trying to never stop the RC!".
The Sketchup file for the stick handles can be found here: StickHandles.skp.
The STL file for the stick handles can be found here: StickHandles.stl.