You need some sort of functional prototype (i.e. something that actually, in some way, does what you want it to do). Nobody will invest without one. You said you're too low on funds to have one built, so my best advice would be to spend some time learning the skills needed to build it yourself. You could for instance take free online electronics courses that MIT provides: https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-002-circuits-and-electronics-spring-2007/ or buy books, watch youtube videos, etc.

I've built my own hardware prototypes for two of my own startups, and also helped build prototypes for others through Clarity. Let me know if you'd like advice more tailored to your specific idea (e.g. the kinds of microcontrollers and motor controllers that might work, etc.)

best,

Lee