Looking very interesting.
Not sure if you have given it much thought yet but you will want to do a fairly comprehensive risk assessment on this once you develop a working prototype. Identify things like pinch points, impact points, the risk of falling etc. As a manufacturer whatever you sell has to be safe and you have to prove that you have safe systems in place because if something happens and someone gets injured using one of these seats at home you could be at the receiving end of a law suit. Having a risk assessment and implementing safe guards for the risks is vital. For instance you may need an emergency stop on the seat, as well as harnesses etc.
Also because it has electrical components and you need to connect it to mains power, you are going to need to get it complied in the relevant areas it will be sold to ensure all your earthing, noise suppression etc is compliant.
Just an observation from an electrical engineering stand point