Where can I find one of these? That is, are there linear actuators where I can specify the force it should apply and it gives me back exactly how much force was applied? Are there any linear actuators that can do this and also give me position feedback, i.e., where my object is after it has been pushed? Why are these unpopular, when force feedback seems like such an obvious requirement? I want to be able to specifically control the force that my actuator applies to my object.