text: Teleoperation of heavy machinery in industry often requires operators to be in close proximity to the plant and issue commands on a per-actuator level using joystick input devices. However, this is non-intuitive and makes achieving desired job properties a challenging task requiring operators to complete extensive and costly training. Despite this, operator fatigue is common with implications for personal safety, project timeliness, cost, and quality. While full automation is not yet achievable due to unpredictability and the dynamic nature of the environment and task, shared control paradigms allow operators to issue high-level commands in an intuitive, task-informed control space while having the robot optimize for achieving desired job properties. In this paper, we compare a number of modes of teleoperation, exploring both the number of dimensions of the control input as well as the most intuitive control spaces. Our experimental evaluations of the performance metrics were based on quantifying the difficulty of tasks based on the well known Fitts' law as well as a measure of how well constraints affecting the task performance were met. Our experiments show that higher performance is achieved when humans submit commands in low-dimensional task spaces as opposed to joint space manipulations.
  @cite_31: In order to enhance operator performance and understanding within remote environments, most research and development of telepresence systems has been directed towards improving the fidelity of the link between operator and environment. Although higher fidelity interfaces are important to the advancement of a telepresence system, the beneficial effects of corrupting the link between operator and remote environment by introducing abstract perceptual information into the interface called virtual fixtures are described. >
  @cite_13: Forbidden region virtual fixtures protect objects from unwanted contact with a robot. In this paper, we propose a method for creating forbidden region haptic virtual fixtures for teleoperation from streaming point clouds obtained by an RGB-D camera. Upon violating the protected area, the operator receives force feedback that opposes motion inside the forbidden region. Three architectures for creating virtual fixtures are presented and their advantages and disadvantages are described. The proposed methods have the ability to implement constraints and can handle dynamic environments in real-time. The effectiveness of the methods is demonstrated in experiments with a surgical robot.
  @cite_23: This paper presents a unique real-time obstacle avoidance approach for manipulators and mobile robots based on the "artificial potential field" concept. In this approach, collision avoidance, traditionally considered a high level planning problem, can be effectively distributed between different levels of control, allowing real-time robot operations in a complex environment. We have applied this obstacle avoidance scheme to robot arm using a new approach to the general problem of real-time manipulator control. We reformulated the manipulator control problem as direct control of manipulator motion in operational space-the space in which the task is originally described-rather than as control of the task's corresponding joint space motion obtained only after geometric and kinematic transformation. This method has been implemented in the COSMOS system for a PUMA 560 robot. Using visual sensing, real-time collision avoidance demonstrations on moving obstacles have been performed.
  @cite_17: Human-robot interaction is becoming an increasingly important research area. In this paper, we present a theoretical characterization of interaction efficiency with an aim towards designing a human-robot system with adjustable robot autonomy. In our approach, we analyze how modifying robot control schemes for a given autonomy mode can increase system performance and decrease workload demands on the human operator. We then perform a case study of the design of a shared-control teleoperation scheme and compare interaction efficiency against a traditional manual-control teleoperation scheme.
summary: Prior work has explored techniques that guide robots motions via synthesized constraints, i.e., potential fields and virtual fixtures. Potential fields, originally developed by Khatib @cite_23 , guide a user towards or away from a goal or obstacle @cite_17 . Virtual fixtures create virtual barriers or forbidden regions in the task space that provide assistance in protecting sensitive areas. Rosenberg @cite_31 provided early work in the development of virtual fixtures. A number of guidance and or preventative virtual fixture designs were compared using a Fitts' law paradigm for a remote teleoperation peg placement task. Later work @cite_13 has developed on-the-fly forbidden region generation techniques using real-time sensor data.