Forgive me, as this is a long as post, Which i hope you read and give me input on. but I tried to
I dont consider modified drills, massagers and brushes or any Variation of existing tools a tickling machine. When someone says "Tickling Machine", What comes to mind is more of a "Tickling Robot". A smart, Algorithm based network of servos, motors, sensors resistors powered by a single or multiple processing units. That to me is the ultimate Tickling machine". It is a problem of design, software, hardware and biology wrapped into one big package.
How do we do this?
The Japanese rib tickler is one example of what I might consider a machine; It is built with servos and motors specifically for the purpose. Unfortunately, it seems to be very brute and harsh, without any feedback mechanism. We all know that nerves become de-sensitized to repetitive and predictable motion. Same problem with the Japanese sole tickler, It just does the same thing to the same location.
For it to be smart and effective, it has to respond to the subject's movement. If the foot goes right, the machine goes right. if the foot goes left, machine goes left. If the upper body squirms to the side, the machine "seeks and destroys" the ticklish spot. luckily, all of this is possible in the current state of technology: Kinect and Body tracking/mapping.
IF you search youtube for kinect projects, you will find tons of videos, Most of which show you body tracking at a across the room distance, which has an accuracy of about 7 centimeters at 5 meters distance. However, at One meeter (think upper body position) the accuracy goes down to only 2 Millimetres. With a couple of kinect 2 (or whatever version is the latest), you can have a full body mapping and tracking system that is accurate enough to track all points of visible and vulnerable skin.
Example of facial mapping:
https://www.youtube.com/watch?v=OzSNj84AY7c
Ex of Body tracking:
https://youtu.be/E1eIg54clGo?t=298
As for the Tickling action, the biggest problem is the pressure applied. the pressure has to be within a specific range for it to be "Gargalesis" or laugh inducing tickling. And here, the current technology is limited to force sensors which have to be placed between the tickling object and the subject's skin. This is a bit more complicated, as Design wise, you need the sensor's feedback to be built into the object. It is easy to attach a sensor to the tickling edge of an object, but then the tickling will come from the sensor itself or whatever is covering it (think felt, or a Silicone like skin cover).
For an example of this:
https://youtu.be/Uak4BuMdA2M
Ideally, you want the object itself to do the measurement for you, so that suppose you use a chopstick like item, the chopstick itself figures out the pressure applied, and delivers the tickling sensation needed.
This is where embedded systems come in. As of now, Graphene seems to be the future star, The technology is still new, underdeveloped and expensive. but maybe in the near future, it will be commercially available at a decent price level. Currently, Scientists embedded Graphene in a silly putty like material, which created a new type of sensor. Suppose you do the same but instead of putty, do it with Silicone, What will happen? would it result in a finger like digit we can use for tickling??
Graphene example:
https://www.youtube.com/watch?v=H6levpUVYZw
A workaround to this is using material that is flexible enough to reach the pressure required without injuring the skin. in my previous attempts, that material was a peacock feather (or any kind of feather), which only provided a relaxing light tickling sensation that was enjoyable if the subject is not too feather ticklish. If they are feather ticklish, and extremely so, then Guess what, It is so easy to build a tickle robot for them kind of folk! Hurraaaay!
SO now that you have the body Mapping, and the sensors and tickle producing objects, how do you put it all together?
this is where robotics and software comes in: You build a robot using Sensors, servos and motors. All of thses are connected to an arduino board or a similar computer like prototyping board. From the hardware point of view: If you are good at Legos, K’nex and problem solving, this turns into a design and architecture problem. You need to build the hardware in a way that positions and connects all components in a way that allows good support, good range of motion and Movement ability relative to the subject’s body.
AS for software: This is the hardest part probably. It will require thousands and thousands likes of code. The code will allow all the components to work and interact with each other, and with the body. Luckily, there are tons of development libraries out there that do the majority of the things we want to do. It becomes a problem of adapting the code that already exists to our purpose, and add new lines of codes for what is missing.
Want the Body mapping? There are libraries for that.
Want the servo and resistors to work? There are libraries for that.
Want the servos to trach the body and body part movements? There are libraries for that.
Want the Tickle robot to tickle the hell out of someone? Well…
We need AI.
Artificial intelligence is in its infancy. But there are a lot of libraries out there we can learn from and adapt to r needs. From a coding point of view, you have inputs and outputs. Inputs are variables for the body position and body parts, Variables for the sounds and movements the subject emits (reactions, physiological condition, heart rate, stress, O2 and sweat output, etc), and Variables for the positions and actions of the servos and tickle edges/objects, and Variables for rests and pauses. it becomes a training problem for the AI to learn from and adapt the output (which is the tickling action) based on the input. Machine learning can do that. But you need a lot of data to train the AI (Think volunteers, Prodding and probing, looking for the ticklish spots, gauging reactions, mapping movement, etc).
So, as you can see, It is very possible to build a fantasy level Tickling machine/robot with the technology that exists, and tech that will be coming out in the next 5 if not 2 years. No need to wait 20. It just needs patience, perseverance and lots and lots of creativity, money and problem solving.
let me know your thoughts?