D McRuer"Man-Machine Systems The Electrical Engineering Handbook Ed. Richard C. Dorf Boca raton crc Press llc. 2000
D. McRuer “Man-Machine Systems” The Electrical Engineering Handbook Ed. Richard C. Dorf Boca Raton: CRC Press LLC, 2000
105 Man-Machine Systems 105.2 Several Natures of Man-Machine Control-A Catalog of Behavioral Complexities 105.3 Full-Attention Compensatory Operations--The Crossover model Crossover Frequency for Full-Attention Operations. Remnant Duane Mcruer Effects of Changes in the Task Variables. Effects of Divided 105.1 Introduction In principle the dynamic behavior of the human element in man-machine systems can be described in terms similar to those used to describe other system elements. There are, however, major complications in quantifi cation because of the enormous versatility of the human engaged, simultaneously, as the on-going architect and modifier of the man-machine system itself and as an operating entity within that system. In other words, the adaptive and learning capabilities of the human permit both set-up and modification of the effective system tructure and the subsequent self-improvement and tuning of the human dynamic characteristics within that The situations which are simplest to quantify are those in which the machine has time-stationary dynamic properties and the human has, after architectural, learning, and adaptation phases, achieved a similar state. and a remnant[ Graham and Mc Ruer, 1961] or operator-induced noise. This is the context here 8fu Under these circumstances human dynamic operations can be characterized by quasi-linear describing functions 105.2 Several Natures of Man-Machine Control-A Catalog of Behavioral Complexities Figure 105.1 [McRuer and Krendel, 1974] shows a general quasi-linear man-machine system with time stationary properties. This diagram is suitable for the description of human behavior in an interactive man- machine system wherein the human responds to visually sensed inputs and communicates with the machine via a manipulator of some sort(e.g, control stick, wheel, pedal, etc. ) This block diagram indicates the minimum needed number of major functional signal pathways internal to the human operator to characterize different behavioral features. The constituent human sensing, data processing, computing, and actuating elements are connected as internal signal processing pathways which can be"reconfigured"as the situation changes. Such reconfiguration is an aspect of human behavior as a system architect. Functional operations on internal signal within a given pathway may also be modified. The specific internal signal organizational possibilities depicted in Fig. 105 1 have been discovered by manip- ulating experimental situations (e.g, by changing system inputs and machine dynamics) to isolate different combinations of the spe ks shown [McRuer and Jex, 1967; McRuer and Krendel 1974; McRuer 1980] To describe the parts of the figure start at the far right with the controlled element. This is the machine beir ontrolled by the human. To its left is the actual interface between the human and the machine-the neuromuscular c 2000 by CRC Press LLC
© 2000 by CRC Press LLC 105 Man-Machine Systems 105.1 Introduction 105.2 Several Natures of Man-Machine Control—A Catalog of Behavioral Complexities 105.3 Full-Attention Compensatory Operations—The Crossover Model Crossover Frequency for Full-Attention Operations • Remnant • Effects of Changes in the Task Variables • Effects of Divided Attention 105.1 Introduction In principle the dynamic behavior of the human element in man-machine systems can be described in terms similar to those used to describe other system elements. There are, however, major complications in quantifi- cation because of the enormous versatility of the human engaged, simultaneously, as the on-going architect and modifier of the man-machine system itself and as an operating entity within that system. In other words, the adaptive and learning capabilities of the human permit both set-up and modification of the effective system structure and the subsequent self-improvement and tuning of the human dynamic characteristics within that structure. The situations which are simplest to quantify are those in which the machine has time-stationary dynamic properties and the human has, after architectural, learning, and adaptation phases, achieved a similar state. Under these circumstances human dynamic operations can be characterized by quasi-linear describing functions and a remnant [Graham and McRuer, 1961] or operator-induced noise. This is the context here. 105.2 Several Natures of Man-Machine Control—A Catalog of Behavioral Complexities Figure 105.1 [McRuer and Krendel, 1974] shows a general quasi-linear man-machine system with timestationary properties. This diagram is suitable for the description of human behavior in an interactive manmachine system wherein the human responds to visually sensed inputs and communicates with the machine via a manipulator of some sort (e.g., control stick, wheel, pedal, etc.). This block diagram indicates the minimum needed number of major functional signal pathways internal to the human operator to characterize different behavioral features. The constituent human sensing, data processing, computing, and actuating elements are connected as internal signal processing pathways which can be “reconfigured” as the situation changes. Such reconfiguration is an aspect of human behavior as a system architect. Functional operations on internal signals within a given pathway may also be modified. The specific internal signal organizational possibilities depicted in Fig. 105.1 have been discovered by manipulating experimental situations (e.g., by changing system inputs and machine dynamics) to isolate different combinations of the specific blocks shown [McRuer and Jex, 1967; McRuer and Krendel 1974; McRuer 1980]. To describe the parts of the figure start at the far right with the controlled element. This is the machine being controlled by the human.To its left is the actual interface between the human and the machine—the neuromuscular Duane McRuer Systems Technology, Inc
HAZARDOUS ENVIRONMENT ROBOTICS D neb Robotics, Inc is an internationally known leader in 3D graphics-based factory simulation, telerobotics, and virtual reality software used widely in the aerospace, automotive, defense, envi Among the company s broad software product line is TELEGRIPTM, which provides 3D graphical interface for previewing, interactive programming, and real-time bilateral control of remote robotic devices. It provides operators a system for safe, quick, and efficient remediation of hazardous environments from a ngle point of control and input that is isolated from virtually all operator hazards. Accurate 3D kinematic models of the robot and work space components allow the operator to preplan and optimize robot trajectories before the program is automatically generated. Control commands are monitored when running in autonomous, teleoperational, or shared control modes to assure procedural safety and Space Admi P. ovides a Deneb Robotics engineer with a view of the robot. (Photo courtesy of National Aeronautics A video camera actuation system, which is the human's output mechanism. This in itself is a complicated feedback control system capable of operating as an open-loop or combined open-loop/closed-loop system, although that ley of complication is not explicit in the simple feedback control system shown here. In the diagram the neuro- muscular system comprises limb, muscle, and manipulator dynamics in the forward loop and muscle spindle and tendon organ ensembles as feedback elements. Again, many more biological sensors and other elements are actually involved; this description is intended only to be generally indicative of the minimum level of complexity associated with the human actuation elements. All of these elements operate within the human at the level from the spinal cord to the periphery. There are other sensor systems, such as joint receptors and peripheral vision, which indicate limb output position. These operate through higher centers and are subsumed in the proprioceptive feedback loop incorpo- rating a block at the perceptual level further to the left in the diagram. If motion cues are present, these too can be associated in similar proprioceptive blocks with feedbacks from the controlled element output The other three pathways shown at the perceptual level correspond to three different types of control operations on the visually presented system inputs. Depending on which pathway is effectively present, the e 2000 by CRC Press LLC
© 2000 by CRC Press LLC actuation system, which is the human’s output mechanism. This in itself is a complicated feedback control system capable of operating as an open-loop or combined open-loop/closed-loop system, although that level of complication is not explicit in the simple feedback control system shown here. In the diagram the neuromuscular system comprises limb, muscle, and manipulator dynamics in the forward loop and muscle spindle and tendon organ ensembles as feedback elements. Again, many more biological sensors and other elements are actually involved; this description is intended only to be generally indicative of the minimum level of complexity associated with the human actuation elements. All of these elements operate within the human at the level from the spinal cord to the periphery. There are other sensor systems, such as joint receptors and peripheral vision, which indicate limb output position. These operate through higher centers and are subsumed in the proprioceptive feedback loop incorporating a block at the perceptual level further to the left in the diagram. If motion cues are present, these too can be associated in similar proprioceptive blocks with feedbacks from the controlled element output. The other three pathways shown at the perceptual level correspond to three different types of control operations on the visually presented system inputs. Depending on which pathway is effectively present, the HAZARDOUS ENVIRONMENT ROBOTICS eneb Robotics, Inc. is an internationally known leader in 3D graphics-based factory simulation, telerobotics, and virtual reality software used widely in the aerospace, automotive, defense, environmental, medical, nuclear, and research communities. Among the company’s broad software product line is TELEGRIP™, which provides 3D graphical interface for previewing, interactive programming, and real-time bilateral control of remote robotic devices. It provides operators a system for safe, quick, and efficient remediation of hazardous environments from a single point of control and input that is isolated from virtually all operator hazards. Accurate 3D kinematic models of the robot and work space components allow the operator to preplan and optimize robot trajectories before the program is automatically generated. Control commands are monitored when running in autonomous, teleoperational, or shared control modes to assure procedural safety. A video camera provides a Deneb Robotics engineer with a view of the robot. (Photo courtesy of National Aeronautics and Space Administration.) D
a key feature of TELEGRIP is a video overlay option that utilizes video to calibrate 3D computer models with the actual environment. The video overlay technique is especially useful for on-line planning applica ons or teleoperations in remote, hazardous, or complex environments such as space, undersea, or nuclear A virtual reality calibration technique was developed for reliable and accurate matching of a graphically simulated environment in 3D geometry with actual video camera views. The system was designed for predictive displays with calibrated graphics that overlay in live video for telerobotics applications. For ample, the system allows an operator to designate precise movements of a robot arm before sending the command to execute Following successful test of the video overlay techniques, an agreement was concluded with Deneb Robotics that allows the company to integrate video overlay into the commercially available telegrip to expand its use in hazardous environment robotics. Courtesy of National Aeronautics and Space Adminis The operator can view the video image of the real world environment(upper right)and the computer's interpretation of the same scene using TELEGRIP.(Photo courtesy of National Aeronautics and Space Administration. control structure of the man-machine system can appear to be open-loop, or combination open-loop/closed-loop, or totally closed-loop with respect to visual stimuli. a when the compensatory block is appropriate at the perceptual level, the human controller acts in response errors or controlled -element output quantities only. Only the Yp block exists", with Ypi and the precognitive block both equal to zero. with the compensatory pathway operational, continuous closed-loop control is exerted on the machine so as to minimize system errors in the presence of commands and disturbances. Compensatory behavior will characteristically be present when the commands and disturbances are random-appearing and when the only information displayed to the human controller consists of system errors or machine outputs In he simple case where the describing function Ype is defined so as to account for the perceptual and neuromus- cular components, the system is single-input/single-output, and the operator-induced noise is neglected, the closed-loop system output/input dynamics will be YY (1051) e 2000 by CRC Press LLC
© 2000 by CRC Press LLC control structure of the man-machine system can appear to be open-loop, or combination open-loop/closed-loop, or totally closed-loop with respect to visual stimuli. When the compensatory block is appropriate at the perceptual level, the human controller acts in response to errors or controlled-element output quantities only. Only the Ype block “exists”, with Ypi and the precognitive block both equal to zero.With the compensatory pathway operational, continuous closed-loop control is exerted on the machine so as to minimize system errors in the presence of commands and disturbances.Compensatory behavior will characteristically be present when the commands and disturbances are random-appearing and when the only information displayed to the human controller consists of system errors or machine outputs. In the simple case where the describing function Ype is defined so as to account for the perceptual and neuromuscular components, the system is single-input/single-output, and the operator-induced noise is neglected, the closed-loop system output/input dynamics will be (105.1) m i Y Y Y Y pe c pe c = 1 + A key feature of TELEGRIP is a video overlay option that utilizes video to calibrate 3D computer models with the actual environment. The video overlay technique is especially useful for on-line planning applications or teleoperations in remote, hazardous, or complex environments such as space, undersea, or nuclear sites. A virtual reality calibration technique was developed for reliable and accurate matching of a graphically simulated environment in 3D geometry with actual video camera views. The system was designed for predictive displays with calibrated graphics that overlay in live video for telerobotics applications. For example, the system allows an operator to designate precise movements of a robot arm before sending the command to execute. Following successful test of the video overlay techniques, an agreement was concluded with Deneb Robotics that allows the company to integrate video overlay into the commercially available TELEGRIP to expand its use in hazardous environment robotics. (Courtesy of National Aeronautics and Space Administration.) The operator can view the video image of the real world environment (upper right) and the computer’s interpretation of the same scene using TELEGRIP. (Photo courtesy of National Aeronautics and Space Administration.)
CTUATMON SYS Distur bances Commands I FIGURE 105.1 Major human operator pathways in a ma and the error/input e (105.2) Thus, for compensatory situations, the man-machine system emulates the classic single-input/single-output feedback system. The output can be made to follow the input and the error can be reduced only by making the open-loop describing function large compared to 1 over the operating bandwidth of the system When the command inputs can be distinguished from the system outputs by virtue of the display(e.g, i and m are shown or detectable as separate entities relative to a reference)or preview (e.g, as in following a curved course)the pursuit block in Fig. 105 1 comes into play and joins the compensatory. The introduction of this new signal pathway provides an open-loop control in conjunction with the compensatory closed-loop error correcting action. The output/input dynamics of the man-machine system will then become (Yi YY and the error/input describing function is Ypir (1054) +yy With the pursuit system organization the error can be reduced by the humans operations in two ways: by naking the open-loop describing function large compared with 1 and by generating a pursuit path describing function which tends to be the inverse of the controlled element. This can, of course, only be done over a limited range of frequencies. The quality of the overall control in the pursuit case can, in principle, be much superior to that where only compensatory operations are possible. An even higher level of control is possible. When complete familiarity with the controlled element dynamics and the entire perceptual field is achieved, the highly skilled human operator can, under certain conditions, generate neuromuscular commands which are deft, discrete, properly timed, scaled, and sequenced so as to result in machine outputs which are almost exactly as desired. These neuromuscular commands are selected e 2000 by CRC Press LLC
© 2000 by CRC Press LLC and the error/input (105.2) Thus, for compensatory situations, the man-machine system emulates the classic single-input/single-output feedback system. The output can be made to follow the input and the error can be reduced only by making the open-loop describing function large compared to 1 over the operating bandwidth of the system. When the command inputs can be distinguished from the system outputs by virtue of the display (e.g., i and m are shown or detectable as separate entities relative to a reference) or preview (e.g., as in following a curved course) the pursuit block in Fig. 105.1 comes into play and joins the compensatory. The introduction of this new signal pathway provides an open-loop control in conjunction with the compensatory closed-loop error correcting action. The output/input dynamics of the man-machine system will then become (105.3) and the error/input describing function is (105.4) With the pursuit system organization the error can be reduced by the human’s operations in two ways: by making the open-loop describing function large compared with 1 and by generating a pursuit path describing function which tends to be the inverse of the controlled element. This can, of course, only be done over a limited range of frequencies. The quality of the overall control in the pursuit case can, in principle, be much superior to that where only compensatory operations are possible. An even higher level of control is possible. When complete familiarity with the controlled element dynamics and the entire perceptual field is achieved, the highly skilled human operator can, under certain conditions, generate neuromuscular commands which are deft, discrete, properly timed, scaled, and sequenced so as to result in machine outputs which are almost exactly as desired. These neuromuscular commands are selected FIGURE 105.1 Major human operator pathways in a man-machine system. e i YYpe c = + 1 1 m i Y YY Y Y pi pe c pe c = + + ( ) 1 e i Y Y Y Y pi c pe c = - + 1 1