On the first look, voice command seems like a reliable man machine interaction technoogy. The human operator speaks a command like “stop” and the robot is executing the command. This allows a soft transition from teleoperated devices towards fully autonomous one. A possible application would be voice operated train.
The main purpose, why voice commanded robots are interesting is because they are within reach of today's technology. The engineers are able to build such systems and they can be deployed for real applications. In the example, with a voice controlled train, the robo-train would understand 20 simple commands and the human operator remains in the loop all the time. THis allows to equip the system with software without bypassing the existing human operator.
If voice commanded robot are a great idea, it is a here to stay, right? Not exactly. The problem with voice commanded robots is, that they are similar to all sorts of robot an AI Technology. Such technology isn't available yet but it has to be invented. The promise is, that after the train is recognizing voice commands, the human operator can reduce it's workload. But how realistic is such a promise?
The main problem with AI technology no matter which sort of them is, that it has a tendency to work not as robot but as artificial life. It is pretty easy to design systems which are not in control of a human operator, and a voice interface is not an exception. The pessimistic prediction is, that a voice controlled trains won't work. After installing the software and explain to the train driver how the system is working it won't fulfill the needs. And even the engineers who have programmed the device doesn't know the reason why.
But let us go a step backward to understand the situation in detail. The idea is, that a voice controlled train reduces the workload for the human driver. Instead of steering the train with a joystick, the human operator has to talk like “move slowly forward”, “hold speed” and so on. Instead of pushing the joystick manual for 10 seconds forward, he speaks a single command in to the micromphone which produces the same effect. The situation is introduced in the literature as a coach system. The human operator plays the role of a coach. He provides only the general goal and the system figures out the detail. Very similar to explaining how to control a train to the newbie.
In such a case, an experience train operator will talk the same way. He will say, “move slowly forward” and the newbie operator has to execute the task The problem with a robot who interacts in such a way is, that he provides an additional complexity not available before. That means, the robot won't simplify the situation but it will make the things difficult to grasp.
Perhaps it make sense to investigate who a coach to newbie interaction works in the classical setup. The experienced trains operator gives a command, for example, he can say “start the engine”. It is up to the newbie train operator to fulfill the request. He has to press a button for starting the engine itself and he has to make sure that the warning light goes off. In response the newbie can answer the request with “engine was started”.
The interesting fact is, that such an interaction has nothing to do with the train itself, but it reflects the communication between two humans who are operating on the engine. Both operators are forming a hierarchy. The experience train operator decides, that the engine has to be started at a certain moment. And the subordinate has to figure out how to do so.
The interaction between an experienced operator and a newbie is the best practice method for teaching a complicated subject to a newbie. Even if somebody has no experiences with train control he is able to play the role of a newbie who has to execute the commands of the operator. The reason why this social role works well is because a human is motivated to play the role o a subordinate. In contrast a voice controlled software won't do so. There is no need for the software to execute the commands from the human operator and at the end the human has to follow the instructions of the robot.