Other examples were mentioned in the section on low-level control. When is force reflection more advantageous than the position control of a locally force-controlled robot? If force reflection is used, what is the exact form of controller that best meets goals of robustness and stability? There is still considerable work to be done in this area.
A new set of issues arises from scaling: teleoperation of very small and very large robots. The mechanical behavior of objects in the micro domain is very different than in the macro domain. One problem is that the dynamics will be very fast; somehow movements will have to be slowed down for the operator.
As robot autonomy improves, so will the level of supervisory control. A number of functions could be increasingly automated:
Path planning and collision avoidance. The main issues here are efficient routines and obtaining geometric descriptions of the environment (Latombe, 1991).
Trajectory specification. Any trajectory has to stay within system constraints of joint limits, actuators, and safety concerns.
Grasping. The robot should be relied on to obtain a stable grasp and to regrasp as necessary.
Intermittent dynamic environments. Trajectories should be modified in real time subject to changes in the environment. For example, a robot may swerve to avoid hitting someone entering its workspace. Some forms of hand-eye coordination, such as catching or hitting, may require a speed of response not possible with teleoperation.
Force control. With more sophisticated abilities to interact with the environment and to complete such tasks as the generic peg-in-hole problem, the need for force reflection will diminish.
A step toward such autonomous control capabilities would be a higher-level transfer of skills between the operator and the telerobot. The idea is to program by kinesthetic demonstrations: the human makes a movement, this movement is measured, and the telerobot extracts symbolic information about how to accomplish the task (Funda et al., 1992; Ikeuchi, 1993). This differs from direct manual teleoperation, in that an exact trajectory is not being commanded, but rather a strategy for completing a task. Difficulties particularly present themselves in transferring force control skills.