Sorry, no experienced based advice from me. But, here is some
thinking on my part... I observe that solenoids are rarely seen in
robotics. So, I think that is your answer. The question is, why?
There are obviously some advantages to servos. By the simpicity of
their design, they are inherantly more reliable, and cheaper.
While most solenoids are on/off type devices, there are proportional
types as well. But, most are the "hammering" type you mention.
Some solenoids are latching... a magnetic force holds it in position
without power until a reverse current is applied.
I just thought of a large scale installation of "robots" that uses
solenoids. I believe the Tiki Hut in Disney uses solenoids for the
birds mouths. This quick motion of a light-weight object is one good
application for solenoids.
And another application comes to mind... actuators for ultra-light
indoor R/C Aircraft. They should be considered rotary solenoids.
These are often home made coils with a magned mounted to pivot in the
middle. Not just, on-off, but proportional control by controling the
current provided to the coil.
In the above two examples, the solenoids are fast acting, but don't
use the mechanical advantage of gears, so they are weak.
If I were to take the rotary solenoid used in the R/C Aircraft, and
attach a gear to the magnet, then repeadly turn it on and off, I will
have turned into a brushless gear motor. Conversely, if i take a
purpose-built brushless gearmotor, then remove the gears, and only
actuate it by applying a DC current, it will function like a rotary
The same thinking can be done with a linear solenoid. If I stack a
bunch of linear solenoids, and put one plunger in it, and then actuate
the coils in series, I will have made a linear motor.
So, with the above thinking, they two devices are essentially the
same, and therefore are likely to share the same force and efficiency.
The difference is if they are designed to actuate over a large range
of motion, or a short range.