Neural interface might be the big problem in prosthetics. Many of the limitations of current prosthetics are due to the janky ass workarounds, like myoelectrics, that are needed to try and facilitate communication between the prosthetics and the brain. Without high fidelity, low latency, bidirectional communication they really don’t have the fluidity and “natural” feel and so it doesn’t feel so much like your body but like a tool that you are using. There’s a reason “the claw” is still preferred by most upper body amputees; it’s a really good tool!
Fairly normal electric motors can have fast and “jerky” movements similar to biological muscles, however the issue is the neural signals that are being used to control the motors are TRASH. Even with direct electrode measurements the signals still have fairly high SNR and are averaged across a large population of hundreds-thousands of neurons. The “bangbang control scheme” then leads to unpredictable destructive/constructive interference that makes the already noisy reading very hard to interpret and act on appropriately. Modern prosthetics are as “good” as they are thanks to predictive control schemes and lots of long term averaging. This high uncertainty and slow response time results in what I think you refer to as the “continuous control” type movement.
At present the best neural interfaces we have cause immunological responses that rapidly destroy the signal integrity within, at best, ~8-12 months via scarring, encapsulation and material degredation. That’s with the best zwitterionic coatings, low young modulus, embedded anti-inflammatories, etc. In the lab optogenetics and other sorts of “biological amplifiers” have resulted in some of the best bidirectional neuronal communication. As far as I’m aware, the last promising candidate of that sort was targeted muscle reinnervation which is unidirectional and still relies on shitty myoelectrics.
Neural interface might be the big problem in prosthetics. Many of the limitations of current prosthetics are due to the janky ass workarounds, like myoelectrics, that are needed to try and facilitate communication between the prosthetics and the brain. Without high fidelity, low latency, bidirectional communication they really don’t have the fluidity and “natural” feel and so it doesn’t feel so much like your body but like a tool that you are using. There’s a reason “the claw” is still preferred by most upper body amputees; it’s a really good tool!
Fairly normal electric motors can have fast and “jerky” movements similar to biological muscles, however the issue is the neural signals that are being used to control the motors are TRASH. Even with direct electrode measurements the signals still have fairly high SNR and are averaged across a large population of hundreds-thousands of neurons. The “bangbang control scheme” then leads to unpredictable destructive/constructive interference that makes the already noisy reading very hard to interpret and act on appropriately. Modern prosthetics are as “good” as they are thanks to predictive control schemes and lots of long term averaging. This high uncertainty and slow response time results in what I think you refer to as the “continuous control” type movement.
At present the best neural interfaces we have cause immunological responses that rapidly destroy the signal integrity within, at best, ~8-12 months via scarring, encapsulation and material degredation. That’s with the best zwitterionic coatings, low young modulus, embedded anti-inflammatories, etc. In the lab optogenetics and other sorts of “biological amplifiers” have resulted in some of the best bidirectional neuronal communication. As far as I’m aware, the last promising candidate of that sort was targeted muscle reinnervation which is unidirectional and still relies on shitty myoelectrics.