Windows – Achieving precise mouse movement despite trembling fingers

I take some medication that causes a constant tremor in my fingers. My old mouse recently died, and I had read that people with essential tremor do better with a trackball, so I bought one. However, it turns out that, at least with the Logitech M570, which has a fairly small trackball, the tremor in my thumb actually makes the trackball considerably harder to use than the regular mouse. Specifically, it is hard to place the mouse pointer exactly, to hit a small button or to place the cursor to a location in a word. Highlighting a small section of a sentence is particularly difficult – this was true with the regular mouse as well. If I slow the mouse down enough to easily hit a small target, even with mouse acceleration on, it takes 11 complete revolutions of the trackball to get from the left edge of my left screen to the right edge of my right screen.

Now, I could go back to a regular mouse, or try a make of trackball with a larger ball. Or I could shell out $150 for SteadyMouse, which might do what I want, or might not, but in either case seems to be priced on the assumption that the consumer's insurance will pay for it. But this seems so obviously a problem that should be amenable to basic settings adjustment or an open-source solution that I am frustrated that I have not yet been able to find one.

Here are some things I think might work, if I knew how to implement them:

First, it seems like mouse acceleration might solve the problem if it just accelerated enough. Some earlier versions of Windows had an acceleration slider like the speed slider, but if there is anything like that in Windows 7 (desktop) or 10 (laptop) I have not been able to find it (an acceleration parameter in the registry, maybe?).

Second, if there was a smoothing setting (as opposed to the "enhance pointer precision" setting, which oddly turns off acceleration) that did averaging over either small movements or short periods of time, I suspect that would provide sufficient stabilization to let me use a pointer speed that is reasonable for large movements.

Finally, I think the basic structure of mouse acceleration, mapping trackball speed to pointer acceleration, misses the point somewhat for people with tremor. Tremors are not slow motions – not at all. I think my thumb tremor moves the trackball faster than I can move it intentionally, for very short distances. What I think would be most helpful is exponential amplification, not of speed, but of distance. I'd like to be able to get across my screen with two or three turns of the trackball, but map a quarter turn to about an inch. But I am pessimistic about this being available in settings or in any other way easily available to me.

I'd be very grateful for any solutions that anyone might suggest.

UPDATE: I have learned that the M670 has its own mouse settings, that override the Windows settings. Start menu > Mouse and Keyboard settings (installed by the M670) > My Mouse tab > Pointer left-edge tab gives you more control over both pointer speed and acceleration. With acceleration at max, I can get all the way across two screens with two quick flings. With speed at minimum, I can usually hit medium-sized buttons from, say, a fifth of a screen to an inch away. Which is some progress.

In addition, I was surprised to learn that Windows has no problem with multiple mouse devices connected at the same time. My old mouse, at its slowest, is considerably slower than the M670 at its. So right now I am keeping both mice beside my keyboard, and using the wired mouse when I need fine control.

But I can not say this seems like a good final result. It takes up a lot of desk space I'd like to have for other things. Going back and forth between two mice is one more thing slowing me down, and I'm plenty slow enough without it. And when I end up a quarter of an inch from a tiny button or the edge of a window I want to resize with my hand on the M670, it makes me crazy that I can not just nudge the cursor that last quarter inch. Small nudges have a half-inch random uncertainty disk added to them. I'm actually better of moving two inches away and hoping to hit the target with a larger motion.

I think I could just use the M670 by itself if I could reduce the minimum speed by half. I think I'll write to Logitech and see if they have some equivalent of registry settings that would let me slow it further.