Certainly you can use any variable voltage input to any controller with a throttle input...but those inputs are generally designed around a specific voltage range that common throttles output, which can be around 1v up to around 4v. (varies with design of throttle, and expected input range varies with controller design--throttles I've seen as low as 0.7v minimum to 3v max, to as high as 1.4v to 4.2v max...controller input ranges vary too).
So using a voltage source that doesnt' have the same output range, especially if it is much smaller than the range expected by the controller, means you don't get the same control range you would with a throttle.
That is where "interpreter devices" become required, unless the controller has a programmable input range.
Otherwise, you have to live with the mismatch between demand device output range (throttle, torque sensor, etc), and the controller's throttle input range.
Such a mismatch can be simply that the demand device doesnt' go high enough in voltage to ask for full power from the controller. Or it can be that the demand device's output starts above the level at which the controller begins responding, so the controller will never shut off and will always run the motor. Or other ranges of consequences.
If the Baserunner has a programmable throttle input that you can setup specifically for the Sempu's output range, then have you done that in the Baserunner setup program, per whatever instructions Grin Tech has given? (assuming they gave any beyond what you quoted, which is insufficient information to help you do what you want, and by itself is not really helpful).
I'd be interested to see their specific setup instructions for this configuration. Their manual and product pages have no references to this method of operation.
The Sempu itself has an output that starts above the typical minimum throttle voltage outputs, according to their pages:
Product Description tab: This sensor has a resting torque voltage of 1.5V that increases to 4.0V with force on the pedals
Spec tab: Torque Scale ~30 to 60 Nm/V
Additional info tab:
Torque Scale: +50.8 Nm/V
Zero Torque: ~1.5 +/- 0.05V
So you should get 1.5v with no feet on pedals, up to 4.0v with maximum force on them.
That means you'd need to setup the Baserunner's throttle input (if it's programmable) to match that range.
If it's not programmable, then you're stuck with whatever the crossover happens to be between the Baserunner's input range, and the Sempu's output range, and whatever behavior this causes.
A caveat of direct connection this way, is if the Sempu's output drifts upward in voltage (apparently not uncommon with torque sensors, probably dependent on environmental factors), past what you've got set as the lower limit in the Baserunner, it'll be telling the Baserunner that you're asking for motor operation even when you don't have your feet on the pedals. To zero this, and prevent undesired motor operation, you'd have to go back into the Baserunner settings, and increase the minimum expected voltage on the throttle input to whatever the Sempu now outputs.
You noted previously that the output voltage on the Sempu you have never varies from 1.4v, when connected to the Baserunner. Is that also true when it is not connected to it?
If it never varies at all, something is probably wrong with it, but I don't know what (I've only used the TDCM and THUN).
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