I think I have read somewhere that for Range Rover electric they have used electric steering pump from new Mini One which also adjusts the assistance based on car’s speed.
Although a simple pump with no variable assistance would make things easier perhaps.
Any recent steering pump should be able to change pressure to vary assistance. The challenge is telling it what to do, which is usually a CAN communication.
It looks like control the unit in the first BMW Mini might be unusually simple, according to this discussion from a BMW forum:
Mini Electric Power Steering Pump...
That discussion is somewhat questionable, because it states that there is no control logic needed, but includes a document showing that the pump's output pressure varies with steering action. It also mentions response to steering action, but not road speed.
Another
article suggests only a simple low/high assist logic, based solely on steering activity:
The electric pump has circuitry which is used to control or "modulate" the power drawn from the car's electrical system as well as control the hydraulic fluid flow according to the steering system demand. This allows the motor to run slower (and draw less power) when there is little or no need for assistance, such as when driving on straight roads or idling in traffic. When the driver turns the steering wheel, the control circuitry built into the pump's motor increases current flow to the motor, making it spin faster and subsequently moving more hydraulic oil through the steering rack at a higher pressure. Sharp turns and tight maneuvering such as city driving, parking and autocross events keep the motor/pump running in an elevated power state. Once the road straightens out, the system returns to a reduced power state to cool off, save power and increase component life.
I also wonder about the motor for this pump - from various Mini forum discussions it appears to be a brushed (presumably PM DC) design, which has wear problems. Surely this thing which runs all the time should be brushless, right?
The whole early BMW Mini setup looks a generation out date in technology to me... but maybe that suits a Defender.
