Adaptive damper for computer-aided systems

Abstract

A computer-assisted system can include a manipulator arm configured to support an instrument, an input device configured to accept user commands to move the instrument, and a damping system coupled to the input device. A controller of the computer-assisted system can be configured to determine an instrument power metric and an input device power metric. The controller can also determine a damping to be applied to the input device based on the instrument power metric and the input device power metric, and cause the damping system to adjust the damping applied to the input device.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application Serial No. 63 / 347,304, filed May 31, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The disclosed embodiments relate to adaptive dampers for computer-assisted systems and related methods of use. Background Art

[0004] Computer-assisted electronic systems are being used more and more frequently, particularly in industrial, entertainment, educational, and other settings. As a medical example, today's medical facilities feature a large number of electronic devices in operating rooms, interventional suites, intensive care units, emergency rooms, and / or similar locations. Many of these electronic devices may be capable of autonomous or semi-autonomous movement. Personnel can remotely control the movement and / or operation of follower electronic devices using one or more leader input devices located at a user control system. For example, robotic telemedicine systems allow medical personnel to remotely operate instruments and perform medical procedures from the patient's side or from a remote location. As a specific example, minimally invasive robotic telesurgery systems allow surgeons to perform procedures on patients from the bedside or from a remote location. Telesurgery generally refers to surgical procedures performed using a surgical system in which the surgeon uses some form of remote control, such as a servomechanism, to manipulate the movement of surgical instruments, rather than directly grasping and moving the instruments manually. In some systems with actuator systems coupled to input devices, the actuator systems can be driven to provide tactile feedback via the input devices. Therefore, there is a need for improved apparatus and methods for operating computer-assisted electronic systems. Summary of the Invention

[0005] In some embodiments, a computer-assisted system includes a manipulator arm configured to support an instrument, an input device configured to receive user commands to move the instrument, a damping system coupled to the input device, and a controller including at least one processor. The controller is configured to: determine an instrument power metric indicative of an amount of power for an instrument interaction, the instrument interaction comprising a physical interaction between at least a portion of the instrument and an instrument environment containing the instrument; determine an input device power metric indicative of an amount of power for feedback provided by the input device in response to the instrument interaction; determine damping to apply to the input device based on the instrument power metric and the input device power metric; and cause the damping system to apply damping to the input device.

[0006] In some embodiments, a method of controlling a computer-assisted system configured to support an instrument, the computer-assisted system including an input device configured to control movement of the instrument and a damping system configured to apply a force to the input device, the method including determining a component of a change in force at the instrument, the component being related to a direction of motion of the input device, and in response to determining that an environmental stiffness experienced by the instrument exceeds a threshold stiffness, determining a feedback force based at least in part on the environmental stiffness and the component of the change in force. The method further includes causing the damping system to drive the input device to apply the feedback force. In some embodiments, a non-transitory computer-readable storage medium can store instructions that, when executed by at least one processor associated with a computer-assisted device, cause the at least one processor to perform the method.

[0007] It should be appreciated that the above-described concepts and additional concepts discussed below can be arranged in any suitable combination, as the disclosure is not limited in this respect. Moreover, other advantages and novel features of the present disclosure will become apparent from the following detailed description of various non-limiting embodiments when considered in conjunction with the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0008] The drawings are not to scale. In the drawings, each identical, or nearly identical, component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component can be called out in every drawing. In the drawings:

[0009] Figure 1 is an illustration of a computer-assisted system in accordance with some embodiments;

[0010] Figure 2 is a block diagram of a computer-assisted system in accordance with some embodiments;

[0011] Figure 3 is an illustration of a control loop for a computer-assisted system in accordance with some embodiments;

[0012] Figure 4 is a simplified illustration of a computer-assisted system during operation in accordance with some embodiments;

[0013] Figure 5 is a simplified illustration of an input device of a computer-assisted system in accordance with some embodiments;

[0014] Figure 6 is a simplified illustration of a computer-assisted system during operation in accordance with some embodiments;

[0015] Figure 7 is a graph depicting experimental results for a computer-assisted system in accordance with some example embodiments described herein; and

[0016] Figure 8A flowchart depicting a method of operating a computer-assisted system is depicted in accordance with some embodiments. DETAILED DESCRIPTION

[0017] Some computer-assisted systems include follower devices that are remotely operated in response to user input received at an input device. In cases where such remote operation is performed with an input device coupled to an actuator system, the actuator system can be driven to provide haptic feedback through the input device based on forces determined to be experienced by some portion of the follower device or by a component supported by the follower device. Controlling such actuator systems to provide such haptic feedback can be difficult, or can result in adverse or inaccurate haptic feedback to a user of the computer-assisted system. For example, in a computer-assisted system in which an input device is employed to remotely operate a manipulator arm, phase loss can be introduced between the input device and the manipulator arm due to the physical separation of the input device from the manipulator arm and associated time delays in transmitting information. In some cases in which a computer-assisted system is used to facilitate remote operation of a manipulator arm, the phase loss can be significant and tends to create instability in the control of the input device and / or actuators of the manipulator arm. As another example, instability in the control of an actuator system used to provide user feedback through an input device based on interactions experienced by a follower manipulator arm of a computer-assisted system can also be caused by variations in the operating environment for the manipulator arm. For example, the manipulator arm can support an instrument that can engage with materials (such as objects) that differ in rigidity or compliance in some operating environments and situations. For example, the instrument can interact with one or more harder or more rigid object surfaces as well as one or more softer (e.g., lower durometer) or more compliant (e.g., lower rigidity) object surfaces. As another example, the instrument can interact with harder or more rigid object bulk / volumes as well as softer (e.g., lower durometer) or more compliant (e.g., lower rigidity) object bulk / volumes in the environment. As yet another example, the instrument can interact with non-solid materials in the environment, such as liquid or gel-type materials (e.g., bulk / volumes). As used herein, the durometer of an object can refer to the resistance of the object to surface deformation, and rigidity can be a measure of the resistance of an object or other material to bulk deformation. As the instrument interacts with these different surfaces, volumes, or non-solid materials, variations in the environmental rigidity or compliance encountered can also introduce instability in controlling actuators of the input device to provide feedback to a user due to rapid increases in forces at the instrument.

[0018] The techniques described in this disclosure can provide various benefits in computer-assisted systems that include an input device and a manipulator arm controlled by the input device, where interaction of the manipulator arm (or a component supported by the manipulator arm, such as an instrument) is used to provide haptic feedback to a user of the input device. Example benefits include helping to maintain stability of the feedback provided by the input device, helping to improve or maintain tracking accuracy between commands received at the input device and motion performed by the manipulator arm. In some embodiments, the disclosed techniques reduce the amount of damping applied to the input device, and little or no damping is applied (e.g., based on human senses detecting little or no detectable) when the manipulator arm remotely operated by the input device is not experiencing reaction forces from the operating environment (e.g., the manipulator arm or an instrument supported by the manipulator arm is not in contact with anything other than air or other gas, or is in free space).

[0019] In some embodiments, the disclosed techniques provide a controller configured to compensate for operating environment impedance encountered by a teleoperated manipulator arm, reducing the likelihood of substantially increasing control loop gains, which reduces the likelihood of presenting unstable force feedback at the input device. One potential benefit includes an adaptive controller for a computer-assisted system that enhances stable force feedback for an input device by applying different damping to feedback provided by the input device when the manipulator arm is experiencing higher environmental stiffness (e.g., contact with a more rigid object or a harder object surface, etc.) compared to when the manipulator arm is experiencing lower environmental stiffness (e.g., in free space, contact with a softer material, etc.). For example, without compensation, contact with a substantially rigid surface (e.g., a bone or another instrument in a surgical example) or a substantially rigid block or some other material that is relatively more rigid (e.g., a more viscous fluid, a harder gel, etc.) can result in a rapid increase in control loop gains due to a rapid increase in input force measured at the instrument for a given amount of motion. As another example, the instrument can interact with blocks of objects in the environment that are harder, more rigid, and blocks of objects that are softer (e.g., less stiff), more compliant (e.g., less rigid). As yet another example, the instrument can interact with non-solid materials in the environment, such as liquid or gel-type materials. As used herein, the stiffness of an object can refer to the resistance of the object to surface deformation, and the rigidity can be a measure of the resistance of an object or other material to volumetric deformation. When the instrument interacts with these different surfaces, blocks, or non-solid materials, the variation in environmental stiffness or compliance encountered can also introduce instability in the control of actuators of the input device providing feedback to the user due to rapid variations in force at the instrument for small motions.

[0020] In some embodiments, the disclosed technology provides a controller configured to compensate for changes in structural stiffness of a kinematic chain including a teleoperational manipulator arm. For example, an extended manipulator arm can be more compliant, less stiff, than a folded or retracted manipulator arm. If uncompensated, the increased compliance and decreased stiffness can also result in an increase in control loop gain. Due to its physical configuration, an extended manipulator arm will generally have a different bending stiffness than a folded or retracted manipulator arm, such that a force applied at the tip of an extended manipulator arm (as compared to a folded or retracted manipulator arm) is more able to flex the manipulator arm due to the increased lever arm.

[0021] In some embodiments, the disclosed technology allows for the use of lower quality input devices. Also, in some embodiments, lower quality input devices can be associated with increased control loop gain, which can make the input device more susceptible to instability. The technology described herein can also be applied in a controller configured to compensate for an increase in feedback control loop gain for input device feedback force caused by one or more sources.

[0022] In some embodiments, a computer-assisted system can employ a method in which a power metric indicative of an amount of power of a physical interaction between a manipulator arm and its respective environment is determined. Likewise, a power metric based on feedback force applied to an input device can be determined. Based on the determined power metrics for the input device and the manipulator arm, a damping of the input device can be determined and applied to the input device. In this way, the damping of the input device can be automatically adjusted based on the feedback force applied to the input device as well as the physical interaction between the manipulator arm and its environment. An adaptive controller according to the exemplary embodiments described herein can be employed in any computer-assisted robotic system, including industrial computer-assisted systems, medical computer-assisted systems, and other appropriate systems, with any associated instruments.

[0023] In some embodiments, a computer-assisted system includes a manipulator arm configured to support an instrument and an input device configured to accept user commands to move the instrument. The manipulator arm can be configured to support multiple instruments that can interact with one or more surfaces, blocks, or other materials. The computer-assisted system can also include an actuator system configured to apply a feedback force to the input device based on a force sensed at the manipulator arm. For example, in the case of a teleoperated computer-assisted system, the actuator system can be driven to apply a force to the input device to reflect or represent a force sensed or detected at the manipulator arm positioned remotely from the input device. In this way, the actuator system can be employed to provide force feedback to a user of the input device. The computer-assisted system can also include a controller configured to control the force applied to the input device, where the controller includes at least one processor configured to execute programming instructions that cause the at least one processor to perform the example methods described herein. At least with reference to Figure 1-Figure 2 An example computer-assisted system is further discussed.

[0024] In some embodiments, a method of controlling a computer-assisted system including a manipulator arm and an input device includes measuring or estimating a power (e.g., a power metric) flowing into an instrument supported by the manipulator arm from an environment surrounding the instrument. For example, the power can be measured or estimated based on contact between the instrument and a workpiece or contact between the instrument and another instrument. Measuring or estimating the power flowing into the instrument can include measuring a force at the instrument or elsewhere on the manipulator arm, as well as measuring or determining a velocity of the instrument. The method can also include measuring or estimating a power flowing into the user input device by measuring or determining a feedback force applied to the input device and measuring or determining a velocity of the input device. The method can also include comparing (after optional scaling) the power metrics for the manipulator arm and the input device. In some embodiments, the comparison can be a difference. Based on the comparison between the manipulator arm power metric and the input device power metric, a damping is determined for the input device. In some embodiments, this determination is primarily based on whether the manipulator arm power metric exceeds the input device power metric. In the case where the manipulator arm power metric is greater (e.g., for a first range of differences), a greater damping can be applied to the input device, for example, based on a strict monotonic relationship (e.g., a positive monotonic relationship) between the damping and the difference between the manipulator arm power metric and the input device power metric. In the case where the manipulator arm power metric is less than or equal to the input device power metric (e.g., for a second range of differences), the damping can be set to a baseline value (e.g., zero or a non-zero value). This baseline value can not be set until the input device power metric exceeds or equals the manipulator arm power metric, so as to not introduce instability in the input device. In this way, the damping is driven based on the difference between the relatively scaled power metrics for the input device and the manipulator arm. Reference is made to the example Figure 8 An example method of controlling a computer-assisted system is further discussed.

[0025] According to example embodiments described herein, a power metric can represent power (e.g., energy) over a time period. For example, in some embodiments, a manipulator arm power metric can indicate energy of an instrument interacting with an instrument environment. Likewise, an input device power metric can indicate feedback provided by an input device in response to instrument interaction. A power metric can include a cumulative of power over a follower time period (e.g., a period of time). The follower time period can begin at a time when an input device is used and feedback force is provided at a user input device, and can end until the input device is released and feedback force is no longer presented at the user input device. In some embodiments, the follower time period can be any length of time that a user uses an input device. In some embodiments, the follower time period can be between 1 ms and 7 hours. According to such embodiments, a power metric can represent energy of manipulator arm interaction and input device interaction over the follower time period. In some embodiments, the follower time period can be composed of several integrals of instantaneous power over an interval time period. That is, in some embodiments, an overall integral of instantaneous power can be determined by a sum of multiple interval integrals over an interval time period. For example, determining a power metric can include repeatedly integrating instantaneous power over an interval time period, and summing each repeated interval integral. In some embodiments, an interval time period can be determined at least in part by an interval of a control loop or servo cycle for a computer-assisted system. For example, an interval time period can be between 0.0005 ms and 10 ms (corresponding to a control loop or servo cycle frequency between 2000 to 100 Hz), but any suitable interval time period can also be employed. Other example time periods are further discussed with reference to other embodiments described herein. Examples of determining a power metric are further discussed with reference to Figure 4-Figure 6

[0026] ​In some embodiments, the adaptive damper is implemented for a computer-assisted system, where the controller for the damper is able to discard excess negative energy generation over time to avoid increasing the damping with a delay in the event that the environment interaction of the manipulator arm changes. For example, if an excess of negative net energy is generated, then once the net energy reaches zero or is negative, the damping can be set to zero or near zero, and the damping can be held at zero or near zero until the generated net energy again becomes positive, which can take a significant amount of time. By discarding negative energy in some embodiments, the time to increase the damping above or near zero can be reduced (e.g., the damping can recover more quickly than a control scheme that does not discard excess negative energy). In some embodiments, the computer-assisted system quickly increases the damping applied to the input device in response to a change in the power metric of the manipulator arm that can move into contact with a surface (e.g., a substantially rigid surface), a block, or other material that causes a rapid increase in the power metric (e.g., more quickly than an embodiment that does not discard excess negative energy), resulting in a rapid increase in the power metric. As previously described, in some embodiments, determining the damping applied to the input device can be based on a comparison (e.g., a difference) between the scaled power metric for the input device and the manipulator arm. In the event that the scaled power metric of the input device exceeds the scaled power metric of the manipulator arm (e.g., in the event that the net power metric is negative), the damping of the input device can be set to a baseline minimum value. In some embodiments, the baseline minimum value can be zero. In other embodiments, the baseline minimum value can be non-zero. In some embodiments, a method of controlling a computer-assisted system includes decaying an excess input device power metric toward a net power metric of zero over time. That is, the method can include reducing the accumulation of the power metric of the instrument interaction over time, and can also include reducing the accumulation of the power metric of the input device interaction over time. For example, in some embodiments, a constant linear ramp rate can be employed to reduce the input device power metric until it equals the manipulator arm power metric. As another example, an exponential decay can be employed to reduce the net power metric. Any suitable profile can be employed to reduce the input device power metric over time, as the present disclosure is not so limited. In this way, when the manipulator arm power metric rapidly increases, the damping can be applied to the input device without the delay introduced by the excess input device power metric.

[0027] In addition to the above, in some embodiments, a damping limit is used to constrain the amount of damping applied to the input device. Applying higher damping to the input device can provide more stable force feedback control on the input device; however, applying higher damping can degrade the user-perceived quality of the feedback or responsiveness of the computer-assisted system. For example, in some applications of a computer-assisted system according to exemplary embodiments described herein (e.g., robotic surgery), movement of the input device can be undesirable when the input device is fighting the motion or is slow relative to an input device without damping. Thus, in some cases, the damping limit is increased at a limited rate of change, thereby reducing the likelihood of a large increase in the amount of damping applied to the input device over a short time span. The“short” time span can be based on the forces, damping, and cycle times associated with the intended use of the computer-assisted system, and thus can vary from system to system. In some embodiments, the“short” time span can include an instantaneous increase (e.g., a step function). In some embodiments, a method of controlling a computer-assisted system can include limiting the amount of damping applied to the input device to a damping limit. In some embodiments, the method can include, in response to determining that the amount of damping is greater than a damping threshold, increasing the damping limit at a known rate. In some embodiments, the damping threshold can be equal to the damping limit, and the damping threshold can also be variable based on the damping limit. For example, if the damping limit is increased, the damping threshold can also be increased accordingly. In this way, in some embodiments, the damping limit can only be increased if the amount of damping continues to exceed the increased damping limit. The rate can be a monotonic rate (e.g., a positive monotonic rate), a linear rate, an exponential rate, or any other suitable rate profile. In some embodiments, the damping limit can be increased up to a maximum damping limit, which can be predetermined based on the particular kinematics of the input device. For example, for a range of difference between the instrument power metric and the input device power metric, the damping can not scale with the difference, as the damping is limited by the damping limit. In some embodiments, in response to the amount of damping being less than the damping limit, the damping limit can be decreased. For example, in some embodiments, the damping limit can be decreased monotonically, linearly, or at an exponential rate. In some embodiments, the damping limit can not be decreased until a threshold period of time has elapsed. This arrangement can ensure that the damping limit remains high in the event that the amount of damping applied to the input device is decreased instantaneously. With reference to Figure 7Exemplary implementations of damping limits and thresholds are further discussed. According to exemplary embodiments described herein, methods can be described without specific reference to directionality. In some embodiments, power metrics and dampings can be directional or assigned directionality. For example, power metrics and dampings can be associated with three non-parallel translational degrees of freedom (e.g., x, y, and z directions). In such embodiments, power metrics and dampings can be determined in each degree of freedom. In some embodiments, dampings and power metrics can be determined in rotational degrees of freedom (e.g., pitch, roll, and yaw directions). In some embodiments, power metrics and dampings can be determined in any number of translational and rotational degrees of freedom or any sub-combination of rotational and translational degrees of freedom. In some embodiments, power metrics can be scalars assigned directionality for the purpose of applying directional dampings. Reference is made to Figure 6 Examples of assigning directionality to power metrics are further discussed.

[0028] According to exemplary embodiments described herein, a "damping" is a force opposite the velocity of an input device. The damping can be a resistive force proportional to the velocity of the input device. Thus, an increase in the velocity of the input device can result in a corresponding increase in the damping force applied opposite the velocity of the input device. According to exemplary embodiments described herein, a method of controlling a computer-assisted system includes applying a damping to an input device with a damping system. The damping can be applied via active forces or passive forces. For example, in some embodiments, actuators of an actuator system can be driven to apply an active damping force in the direction of input device motion or in the opposite direction in the form of a damping. Such a damping force can be incorporated into the overall force output of the actuator system. As another example, in some embodiments, the damping system can include an adjustable physical damper (e.g., a brake system) that can apply a damping force to the input device. As yet another example, the physical damper can be physically adjusted to change the damping rate of the physical damper. Thus, determining a quantity of damping and applying it to such an input device can include adjusting the physical damper to achieve the desired amount of damping. Any combination of physical dampers and actuators operating as dampers can be used as part of a damping system as the disclosure is not so limited. While in some embodiments herein the damping is proportional to velocity (e.g., linear), in other embodiments the damping can be non-linear, piece-wise linear, etc.

[0029] According to example embodiments described herein, power metrics of the manipulator arm and the input device can be employed to determine the damping to be applied to the input device. In some cases, the manipulator arm and the input device can be scaled with different scalings, such that when directly compared, the power metric of one of them can be much greater than the power metric of the other. For example, the manipulator arm can move distances on the order of 1 m, while the input device can move distances on the order of 10 cm. Thus, when directly compared, the manipulator arm power metric can be an order of magnitude greater than the input device power metric. Accordingly, in some embodiments, the power metrics of the manipulator arm and the input device can be determined with appropriate scaling, such that they can be properly compared. In some embodiments, such scaling can be based on a scaling factor of the position tracking between the input device and the manipulator arm, or based on a scaling factor of the forces experienced by each side of the teleoperated robot. Any suitable scaling factor for the power metric can be employed, as the present disclosure is not limited in this respect. In example embodiments described herein, the power metrics of the manipulator arm and the input device are generally described such that an increase in the power metric corresponds to an increase in the amount of power or energy, a decrease in the power metric corresponds to a decrease in the amount of power or energy, and a greater power metric corresponds to a greater amount of power or energy as compared to a lower or smaller power metric. It can be appreciated that merely mathematical manipulation of the numerical value of the power metric does not change the underlying amount of power associated with that numerical value. For example, in a system whose mathematical manipulations or calculations associate lower or smaller (including negative or more negative) numerical values with power metrics corresponding to a greater amount of power or energy, the lower or smaller numerical values correspond to greater power metrics.

[0030] According to example embodiments described herein, a method of controlling a computer-assisted system includes determining and applying damping as part of a control loop. In some embodiments, the control loop can operate at a frequency suitable for attenuating vibrations in a target frequency band. The method according to embodiments described herein can be used to attenuate vibrations of an input device less than or equal to 10 Hz. Accordingly, the control loop can operate at a frequency greater than 100 Hz to 1000 Hz. In some embodiments, the control loop can operate at a frequency range more than ten times the upper limit of the target frequency range. In some embodiments, the speed of the control loop can determine a cumulative time period for the power metric determined during a control loop cycle. In some embodiments, the power metric can be accumulated (e.g., integrated) over a time period, which can be broken down into a sum of multiple interval time periods (e.g., where the interval time periods are associated with control loop cycle times or servo cycle times). The control loop can operate at any other frequency depending on the particular computer-assisted application, as the present disclosure is not limited in this respect.

[0031] The present disclosure describes various devices, elements, and portions of computer-assisted devices and elements in terms of their states in three-dimensional space. As used herein, the term "position" refers to the location of an element or portion of an element. Position can be determined in any number of dimensions appropriate for the system, such as in one-, two-, or three-dimensional space (e.g., three translational degrees of freedom along Cartesian x, y, and z coordinates). As used herein, the term "orientation" refers to the rotational placement of an element or portion of an element. Orientation can be determined in any number of dimensions appropriate for the system, such as in one, two, or three degrees of freedom (e.g., in three rotational degrees of freedom such as roll, pitch, and yaw, which can be represented in terms of angle-axis, rotation matrix, quaternion, and / or the like). As used herein, and with respect to devices having repositionable arms and / or other repositionable structures, the term "proximal / distal" refers to the direction along the kinematic chain of the computer-assisted device toward the base of the computer-assisted device, and "distal / proximal" refers to the direction along the kinematic chain away from the base.

[0032] As used herein, the term "pose" refers to the multi-degree-of-freedom (DOF) spatial position and orientation of a coordinate frame of interest attached to a rigid body. Generally, a pose includes a pose variable for each DOF in the pose. For example, a complete 6-DOF pose in three-dimensional space for a rigid body would include 6 pose variables corresponding to 3 position DOFs (e.g., x, y, and z) and 3 orientation DOFs (e.g., roll, pitch, and yaw). Meanwhile, a 3-DOF position pose for a rigid body would include only pose variables for the 3 position DOFs. Also, a 3-DOF orientation pose for a rigid body would include only pose variables for the 3 rotational DOFs. Further, the velocity of a pose captures the change in the pose over time (e.g., the first derivative of the pose). For a complete 6-DOF pose for a rigid body, the velocity would include 3 translational velocities and 3 rotational velocities (e.g., both angular and translational velocities). A pose with other numbers of DOFs would have a corresponding number of velocities, translational and / or rotational. Other examples include two translational and one rotational DOF, two or three translational DOFs, two or three rotational DOFs for a rigid body.

[0033] Aspects of the present disclosure are described with reference to computer-assisted systems and devices, which can include teleoperated, remote-controlled, autonomous, semi-autonomous, robotic, and / or the like systems and devices. Moreover, aspects of the present disclosure are described in terms of implementations using surgical systems. However, those of ordinary skill in the art will appreciate that the inventive aspects disclosed herein can be embodied and implemented in various ways, including robotic and, if applicable, non-robotic embodiments and implementations. The implementations on surgical systems are merely exemplary and should not be considered limiting of the scope of the inventive aspects disclosed herein. For example, techniques described with reference to surgical instruments and surgical methods can be used in other contexts. Thus, the instruments, systems, and methods described herein can be used on humans, animals, a portion of a human or animal anatomy, industrial systems, general purpose robots, or teleoperated systems. As further examples, the instruments, systems, and methods described herein can be used for non-medical purposes, including industrial uses, general robotic uses, sensing or manipulating non-tissue workpieces, cosmetic improvements, imaging of human or animal anatomy, gathering data from human or animal anatomy, setting up or tearing down systems, training medical or non-medical personnel, and / or the like. Additional example applications include procedures performed on tissue removed from a human or animal anatomy (not returned to the human or animal anatomy), and procedures performed on human or animal cadavers. Moreover, these techniques can also be used for medical treatment or diagnostic procedures that include or exclude surgical aspects.

[0034] It should also be noted that while some embodiments described herein employ rigid linkages, the present disclosure is not so limited. The techniques and methods described herein can be applied to flexible robotic systems. For example, the methods described herein can be applicable to rigid link robot systems, flexible catheter systems, or other flexible robotic systems.

[0035] Turning to the drawings, specific non-limiting embodiments are described in greater detail. It should be understood that the various systems, components, features and methods described in relation to these embodiments can be used individually and / or in any desired combination, as the present disclosure is not limited to only the specific embodiments described herein.

[0036] Figure 1 is a simplified diagram of an example computer-assisted system in accordance with various embodiments. In some examples, the computer-assisted system is a teleoperated system 100. In medical examples, the teleoperated system 100 can be a teleoperated medical system, such as a surgical system. As shown, the teleoperated system 100 includes a follower device 104 that can be teleoperated by control from one or more leader input devices 106, which are configured to accept external input, as will be described in greater detail below. A system including a leader device and a follower device is referred to as a leader-follower system. As Figure 1As shown, the input devices are part of an input system that includes a workstation 102 (e.g., a console). In other embodiments, the input system can be in any suitable form and can or can not include a workstation 102.

[0037] In Figure 1 exemplary embodiments, the workstation 102 includes one or more input devices 106 configured to be contacted and manipulated by a user 108. For example, the workstation 102 can include one or more input devices 106 configured to be used by a hand, head, or some other body part of the user 108. The input devices 106 in this example are supported by the workstation 102 and can be mechanically grounded. In some embodiments, an ergonomic support 110 (e.g., a forearm rest) can be provided on which the user 108 can rest his or her forearms. In some examples, the user 108 can perform tasks at a work site during a procedure by commanding the follower device 104 using the input devices 106. In some embodiments, the workstation 102 can be physically located near the follower device 104. In other embodiments, the workstation 102 can be located away from the follower device 104 and can communicate with the follower device via one or more communication protocols over a local area network, a wide area network, and / or via the Internet.

[0038] As Figure 1 shown, the workstation 102 includes a display unit 112. The display unit 112 can display images for viewing by the user 108. In some embodiments, the display unit 112 can be movable in various degrees of freedom to accommodate the viewing position of the user 108 and / or optionally provide control functions as another input device. In examples of the teleoperational system 100, the displayed images can depict a work site at which the user 108 performs various tasks by manipulating the input devices 106 and / or the display unit 112. In some examples, the workstation 102 can receive the images displayed by the display unit 112 from one or more imaging devices disposed at the work site. In other examples, the images displayed by the display unit 112 can be generated by the display unit 112 (or by a different connected device or system), such as for tools, virtual representations of the work site, or for user interface components.

[0039] According Figure 1 to embodiments, when using the workstation 102, the user 108 can sit in a chair or other support in front of the workstation 102, position his or her eyes in front of the display unit 112, manipulate the input devices 106, and rest his or her forearms on the ergonomic support 110 as needed. In some embodiments, the user 108 can stand at the workstation or assume other postures, and the positions (height, depth, etc.) of the display unit 112 and the input devices 106 can be adjusted to accommodate the user 108.

[0040] In some embodiments, one or more input devices 106 can be ungrounded (ungrounded input devices have no kinematic ground, such as a user 108’s hand holding the input device without additional physical support). Such ungrounded input devices can be used in conjunction with display unit 112. In some embodiments, user 108 can use display unit 112 located near the work site, such that user 108 manually operates instruments at the work site while viewing images displayed by display unit 112, such as laparoscopic instruments in a surgical example.

[0041] Teleoperational system 100 can also include a follower device 104 that can be commanded by workstation 102. In medical examples, follower device 104 can be located near an operating table (e.g., a table, bed, or other support) on which a patient can be positioned. In some medical examples, a work site is provided on the operating table, e.g., on or in the patient, a simulated patient, or a model, etc. (not shown). The illustrated follower device 104 includes a plurality of manipulator arms 120, each configured to be coupled to an instrument assembly 122. Instrument assembly 122 can include, for example, an instrument 126. In various embodiments, one or more of instruments 126 can include an imaging device (e.g., an optical camera, a hyperspectral camera, an ultrasound sensor, etc.) for capturing images. For example, one or more of instruments 126 can be an endoscope assembly that includes an imaging device that can provide captured images of a portion of the work site to be displayed via display unit 112. One or more instruments 126 can also include instruments configured to function in the operating environment and physically interact with physical objects or properties of the operating environment (e.g., in a medical example, the operating environment can be a work space within or outside of a patient). Examples of potential instruments 126 can include, but are not limited to, graspers, scalpels, staplers, imagers or other sensors, cauterizing instruments, suction-irrigators, and scissors. Any suitable instrument can be used with manipulator arms 120, as the present disclosure is not so limited.

[0042] In some embodiments, manipulator arm 120 and / or instrument assembly 122 can be controlled to move and articulate instrument 126 in response to user 108's manipulation of input device 106, and in this way "follow" input device 106 by teleoperation. This enables user 108 to perform tasks at a work site using manipulator arm 120 and / or instrument assembly 122. Manipulator arm 120 and follower device 104 are examples of repositionable structures on which instruments, such as manipulator instruments or imaging instruments that include imaging devices, can be mounted. The repositionable structure(s) of a computer-assisted system comprise a repositionable structure system of the computer-assisted system. For a surgical procedure example, user 108 can direct follower manipulator arm 120 to move instrument 126 to perform a surgical procedure at an internal surgical site through a minimally invasive port or natural orifice. Manipulator arm 120 and / or instrument assembly 122 can also provide feedback information presented to user 108 through input device(s) 106. For example, in some embodiments, manipulator arm 120 and / or instrument assembly 122 can provide force information used to exert a feedback force at input device(s) 106.

[0043] As shown, control system 140 is provided external to workstation 102 and in communication with workstation 102. In other embodiments, control system 140 can be provided in workstation 102 or in follower device 104. As user 108 moves input device(s) 106, sensed spatial information, including sensed position and / or orientation information, based on the movement of input device 106 is provided to control system 140. Control system 140 can determine control signals or provide control signals to follower device 104 based on the received information and user input to control movement of manipulator arm 120, instrument assembly 122, and / or instrument 126. In one embodiment, control system 140 supports one or more wired communication protocols (e.g., Ethernet, USB, and / or the like) and / or one or more wireless communication protocols (e.g., Bluetooth, IrDA (infrared data communications), HomeRF (home radio frequency), IEEE 1002.11, DECT (digital enhanced cordless telecommunications), wireless telemetry, and / or the like). In some embodiments, control system 140 can be configured to implement the example methods herein and determine feedback forces to be exerted to input device(s) 106.

[0044] The control system 140 can be implemented on one or more computing systems. The one or more computing systems can be used to control the follower device 104. In addition, the one or more computing systems can be used to control movement of components of the workstation 102, such as the display unit 112.

[0045] As shown, the control system 140 includes a processor 150 and a memory 160 that stores a control module 170. In some embodiments, the control system 140 can include one or more processors, non-persistent storage (e.g., volatile memory, such as random access memory (RAM), cache memory), persistent storage (e.g., a hard disk, an optical drive (such as a compact disk (CD) drive or digital versatile disk (DVD) drive), flash memory, etc.), a communication interface (e.g., a Bluetooth interface, an infrared interface, a network interface, an optical interface, etc.), and many other elements and functions. In addition, the functionality of the control module 170 can be implemented in any technically feasible software and / or hardware.

[0046] Each of the one or more processors of the control system 140 can be an integrated circuit for processing instructions. For example, the one or more processors can be one or more cores or microcores of a processor, a central processing unit (CPU), a microprocessor, a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a graphics processing unit (GPU), a tensor processing unit (TPU), and / or the like. The control system 140 can also include one or more input devices, such as a touchscreen, a keyboard, a mouse, a microphone, a touchpad, an electronic pen, or any other type of input device.

[0047] The communication interface of the control system 140 can include an integrated circuit to connect the computing system to a network (not shown) (e.g., a local area network (LAN), a wide area network (WAN) such as the Internet, a mobile network, or any other type of network) and / or another device, such as another computing system.

[0048] In addition, the control system 140 can include one or more output devices, such as a display device (e.g., a liquid crystal display (LCD), a plasma display, a touchscreen, an organic LED display (OLED), a projector, or other display device), a printer, a speaker, an external storage device, or any other output device. One or more of the output devices can be the same as or different from the input device(s). There are many different types of computing systems, and the input and output device(s) described above can take other forms.

[0049] In some embodiments, the control system 140 can be connected to or be part of a network. The network can include multiple nodes. The control system 140 can be implemented on one node or a group of nodes. By way of example, the control system 140 can be implemented on a node of a distributed system that is connected to other nodes. By way of another example, the control system 140 can be implemented on a distributed computing system having multiple nodes, where different functions and / or components of the control system 140 can be located on different nodes within the distributed computing system. Further, one or more elements of the control system 140 described above can be located at a remote site and connected to other elements through a network.

[0050] Software instructions in the form of computer readable program code to perform embodiments of the disclosure can be stored in whole or in part, temporarily or permanently, in non-transitory computer readable medium such as a CD, DVD, storage device, a diskette, a tape, flash memory, physical memory, or any other computer readable storage medium. Specifically, the software instructions can correspond to computer readable program code that, when executed by a processor(s) (e.g., the processor 150), is configured to perform embodiments of any of the methods described herein.

[0051] Figure 2 is a block diagram of a computer-assisted system according to some embodiments. As Figure 2 shown, the computer-assisted system includes an input device 200. The input device can be configured to receive external inputs from a user. For example, the input device provides a user interface through which a user can impart physical motions and forces to the user interface that are reflected in a following manipulator arm. That is, the manipulator arm can move based on inputs received at the input device based on a predetermined scaling factor. As Figure 2 shown, the input device includes actuator(s) 204. The actuator(s) 204 can be configured to apply forces to the input device to provide feedback to a user of the input device. For example, the actuator(s) can be configured to apply forces based on forces sensed at the manipulator arm 250. The actuator(s) can include one or more motors, servos, stepper motors, brushless motors, pneumatic actuators, or any other suitable actuator. The actuator can be part of an actuator system that includes the actuator(s) and / or one or more other actuators. Thus, while the actuator(s) are shown in Figure 2 as part of the input device, in other embodiments, the actuators can be provided as a separate actuator system. As Figure 2As shown, the input device may optionally include damper(s) 206. The damper(s) may be adjustable, such that the amount of damping applied to the input device is controlled by the processor(s) (e.g., 302) according to the methods described herein. In some embodiments, the damper(s) may include brakes that, when engaged, can apply a constant or variable braking force to the input device. In some embodiments, the actuator(s) 204 may function as dampers (e.g., by applying resistance opposing movement of the input device), in which case a physical damper may not be employed. According to exemplary embodiments herein, the actuator(s) and damper(s) may form part of a damping system, which may include components of the input device and other components. The damping system may be configured to apply a damping force to the input device. Some components of the damping system (e.g., the actuators) may function as both a feedback system and a damping system (e.g., the force output of the actuators may include both a damping force and a feedback force).

[0052] like Figure 2 As shown, the input device 200 also includes optional sensor(s) 208. The sensors may include accelerometers, inertial measurement units, contact sensors, force sensors, rotary encoders, potentiometers, position sensors, velocity sensors, or other desired sensors, configured to provide information about the input device and its environment to the processor(s) (e.g., 302). In some embodiments, the actuator(s) 204 may provide information about the force applied to the input device and the position of the input device to the processor(s) (e.g., 302). For example, force may be measured by converting motor torque and / or current into force. As another example, position may be measured by monitoring the number of steps of a stepper motor or otherwise monitoring the speed of the motor over time. In such examples, no additional sensors may be employed in the input device. In some embodiments, the input device may include one or more processors (not shown). The processor(s) may be configured to execute programmed instructions that may enable the input device to communicate, sense user input, and provide feedback to the user based on outputs from the manipulator arm 250.

[0053] according to Figure 2In embodiments, the manipulator arm 250 is configured to cooperate with the input device 200. For example, the manipulator arm 250 can be configured to follow user input at the input device 200. Like the input device 200, the manipulator arm includes actuator(s) 254. The actuator(s) 254 can be configured to apply force to the manipulator arm to move the manipulator arm and apply force to the instrument environment. In addition, the actuator(s) can be used to operate one or more instruments associated with the manipulator arm 250. The actuator(s) can be configured to move the manipulator arm based on movement of the input device 200. The actuator(s) 254 can include one or more motors, servos, stepper motors, brushless motors, pneumatic actuators, or any other suitable actuator. As Figure 2 shown, the manipulator arm can optionally include one or more instruments 256. The one or more instruments can be coupled to the manipulator arm and, in some embodiments, can be removable and interchangeable. The instrument(s) 256 can include one or more of an imaging device, a grasper, a scalpel, a stapler, a knife, a cauterizing instrument, and scissors.

[0054] As Figure 2As shown, the manipulator arm 250 also includes optional sensor(s) 258. The sensors can include accelerometers, inertial measurement units, contact sensors, force sensors, rotary encoders, potentiometers, position sensors, velocity sensors, or other desired sensors configured to provide information about the manipulator arm and its environment to the processor(s) (e.g., 302). In some embodiments, the sensor(s) can be configured to provide information about contact forces on the manipulator arm, position of the manipulator arm, and velocity of the manipulator arm to the processor(s) (e.g., 302). In some embodiments, the actuator(s) 254 can provide information about the forces applied to the manipulator arm and the position of the manipulator arm to the processor(s) (e.g., 302). For example, the forces can be measured by converting motor torque and / or current to force. As another example, the position and / or velocity can be measured by monitoring the number of steps of a stepper motor or otherwise monitoring the speed of a motor over time. In some embodiments, the sensor(s) 258 can include force sensors positioned at a distal portion of the instrument. In some embodiments, the distal portion of the instrument includes an end effector of the instrument. The end effector is configured to interact with the environment, such as manipulating the environment and / or sensing data from the environment. Examples of end effectors include end effectors with manipulating components, such as fingers, suction devices, irrigators, cutters. Examples of end effectors also include end effectors with sensor components, such as optical imaging devices, temperature or force sensors, and ultrasound probes. In some embodiments, the sensor(s) 258 can include one or more strain gauges positioned on a portion of the manipulator arm. The manipulator arm 250 can include any suitable number and type of sensors as the disclosure is not limited in this regard. In some embodiments, the manipulator arm can include a processor(s) (not shown). The processor(s) can be configured to execute programmed instructions that can allow the manipulator arm to communicate based on inputs at the input device 200, sense its environment, and interact with its environment.

[0055] According to Figure 2In some embodiments, the computer-assisted system includes a control system 300 that can coordinate and control the interoperation between the input device 200 and the manipulator arm 250. The control system 300 can implement methods for controlling the operation of the input device 200 and the manipulator arm 250 according to the example embodiments described herein. In particular, the control system receives input from the input device 200 and can provide feedback from the manipulator arm 250 to the input device. The control system also sends commands to the manipulator arm 250 based on the input received at the input device 200 and receives sensor feedback from the manipulator arm. The system 300. The control system 300 can control the output of the actuator(s) of both the manipulator arm 250 and the input device 200 in one or more control loops. In some embodiments, the control system 300 can cooperate with the processor(s) of the input device and the manipulator arm to control the input device and the manipulator arm.

[0056] As Figure 2 illustrated, the control system includes one or more processors 302 configured to execute programmed instructions that cause the one or more processors to perform the example methods described herein. The programmed instructions can be stored on a memory 304, which can be a non-transitory memory. In some embodiments, the control system 300 can include or be in communication with any processor(s) of the input device and / or any processor of the manipulator arm to control the input device and the manipulator arm. In some embodiments, the control system can be physically implemented in one electronic circuit (e.g., one integrated circuit). In other embodiments, the control system can be physically implemented in multiple electronic circuits (e.g., multiple integrated circuits) that are co-located or distributed physically relative to one another. In some embodiments, the processors of the control system can be physically disposed in or on the input device, the manipulator arm, another portion of the computer-assisted system, or any combination thereof. In the example described herein, the control system 300 also includes a communication interface 306 that can facilitate the communication of commands, requests, and information between the manipulator arm, the input device, and the control system 300. The communication interface 306 can include circuitry for connecting the control system to a network (not shown) (e.g., a local area network (LAN), a wide area network (WAN) such as the Internet, a mobile network, or any other type of network) and / or to another device (such as another control system). In some embodiments, the manipulator arm 250 and the input device 200 can also include a communication interface to facilitate communication with the control system 300.

[0057] Figure 3 is a diagram of a control loop for a computer-assisted system according to some embodiments. As Figure 3As shown, the input to the control loop is the force from the user. The force from the user can be applied to an input device and monitored by one or more processors of the input device. That is, the one or more processors of the input device can receive information from one or more sensors and / or actuators of the input device, which can be used to determine the force input from the user. In block 400, the overall motion and force of the input device are represented. The motion and force are the result of a combination of the force input by the user and feedback from the control loop. In block 402, the positional movement and / or force of the input device are scaled. This scaling can be based on kinematic differences between the input device and the manipulator arm. For example, the range of motion of the input device may be much smaller than that of the manipulator arm, so the motion and force of the input device are scaled to match the larger range of motion of the manipulator arm. In some embodiments, when information is transferred from the physical input device to the physical manipulator arm, the scaled motion and force are used to command the virtual manipulator arm. This step may employ inverse kinematics to provide the commanded position or motion to the virtual or actual manipulator arm. Alternatively, this step may not employ inverse kinematics. For example, some systems utilize a user input device to command a manipulator arm having similar or identical kinematics to the input device, and such systems can command the joint positions or motions of the manipulator arm directly based on the joint positions or motions of the input device, without employing inverse kinematics. In block 406, a filter may be employed to reduce noise or adjust phase. Any suitable filter may be employed, as the present disclosure is not limited in this regard. In block 408, the manipulator arm is controlled based on the filtered signal provided by the virtual manipulator arm. That is, the manipulator arm moves proportionally based on the movement at the input device in block 400.

[0058] like Figure 3 As shown, the manipulator arm of box 408 provides a feedback signal. The feedback signal can be based on a force measured at the manipulator arm, which can be presented to the input device so that the user feels feedback in response to the force experienced by the manipulator arm. In particular, in box 410, the manipulator arm can interact with its environment. As a result of this interaction, one or more sensors on the manipulator arm can be used to measure the force. In box 412, the force signal can be filtered to reduce noise or target-specific frequency response range. The force feedback filter of box 412 can include determining damping and applying it to the input device to avoid instability in the input device. Therefore, box 412 can represent the exemplary method described herein. In other embodiments, a separate branch of the loop can extend from box 400, which can provide a damping input to the input device output. For example, an additional loop can apply a force based on the determined damping and the velocity of the input device. In box 414, a force feedback gain can be applied to the filtered force feedback signal to change the amount of feedback force presented to the user at the input device. As shown Figure 3As shown, the force feedback is then returned into the input device for presentation, thereby forming a closed control loop. As will be discussed further below, Figure 3 The control loop shown can include determining a damping and applying it to the input device.

[0059] Figure 4 is a simplified illustration of a computer-assisted system during operation according to some embodiments, illustrating a method of controlling the computer-assisted system. As Figure 4 As shown, the computer-assisted system includes an input device 106 and a manipulator arm 120. The manipulator arm includes an instrument 126 having a distal portion 107 (e.g., an end effector, etc.) that physically interacts with an environment 500. Depending on the particular application, the environment can include different objects (e.g., a table, a work surface, a part, a floor, a wall, a ceiling) having different mechanical properties and / or different objects having different non-solid materials (e.g., a gel, a liquid, a gas). Examples of objects include a subject (e.g., a patient, a portion of a patient’s anatomy, an industrial workpiece, a training device). As previously mentioned, the input device 106 and the manipulator arm 120 can be remotely located from one another and can communicate via a control system configured to coordinate the operation of the input device and the manipulator arm. The manipulator arm can be configured to proportionally follow the movement and force applied to the input device by a user. That is, the user input received at the input device can be the basis for commands sent to the manipulator arm to move and interact with the environment 500.

[0060] According to embodiments of Figure 4 parameters for determining a damping level for an input device are shown. In particular, according to embodiments of Figure 4 damping of an input device 106 is determined based on a power metric associated with the input device and a manipulator arm 120. As Figure 4 As shown, a power metric between the manipulator arm and the environment can be determined as P_env. This power can be calculated by determining the force and velocity of the portion of the manipulator arm that is engaged with the environment 500. For example, the power metric can be calculated as the force at the distal portion 107 multiplied by the velocity of the distal portion. In some embodiments, the power metric can be determined by the product of rotational velocity and applied torque. In some embodiments, the power metric can be determined by the product of translational velocity and translational force, as Figure 4 As shown, a power metric between the manipulator arm and the environment can be determined as P_env. This power can be calculated by determining the force and velocity of the portion of the manipulator arm that is engaged with the environment 500. For example, the power metric can be calculated as the force at the distal portion 107 multiplied by the velocity of the distal portion. In some embodiments, the power metric can be determined by the product of rotational velocity and applied torque. In some embodiments, the power metric can be determined by the product of translational velocity and translational force, as Figure 4As shown, the power metric of the input device can be determined as a combination of the power of the force feedback P_ffb and the power of the damper P_Damper. In some embodiments, these power metrics can be determined based on the velocity of the input device 106 multiplied by the force applied to the input device by one or more actuators. Based on the combination of these power metrics, the damping of the input device 106 can be determined. In particular, in some embodiments, the excess power can be determined based on a comparison of the power metrics according to the following equation:

[0061]

[0062] Where α is a scaling factor. In some embodiments, if P_excess is less than or equal to 0, the damping of the input device can be set to zero. In some embodiments, if P_excess is greater than 0, the damping can be set based on the following equation:

[0063]

[0064] Where K is a gain factor, which can be set depending on the specific kinematics of the computer-assisted system. In some embodiments, as previously described, the accumulation of a power metric can be used to determine the damping of the input device. For example, the excess energy E_excess can be determined by integrating P_excess over a specific time period. In such embodiments, the energy can be used to set the damping factor when the energy is greater than zero, according to the following equation:

[0065]

[0066] where K is a gain factor that can be set depending on the specific kinematics of the computer-assisted system. Thus, the damping for the input device can be determined and applied to the input device based on the power measurements at the input device and the manipulator arm.

[0067] Figure 5 is a simplified illustration of the input device 106 of a computer-assisted system according to some embodiments. Figure 5 As shown, the input device 106 includes a virtual damper 103. According to some embodiments, the virtual damper 103 has a damping coefficient B_A.Damper, which can be obtained by referring to the above reference. Figure 4 The process described is to determine Figure 5 In some embodiments, the damper may be virtual in that the actuator is configured to apply an active force in a direction opposite to the direction of the velocity of the input device. In other embodiments, the damper may be a physical damper with an adjustable damping rate. Figure 5The embodiment of FIGURE 1 shows a damper in one direction, but in other embodiments, damping may be applied in multiple degrees of freedom, including translational degrees of freedom (e.g., x, y, and z Cartesian directions), rotational degrees of freedom (e.g., pitch, roll, and yaw directions), or any combination or subcombination thereof. Figure 6 Applying damping in multiple directions is further described.

[0068] Figure 6 is a simplified illustration of a computer-assisted system during operation according to some embodiments. Specifically, Figure 6 1 shows the use of directionality in determining and applying damping to the input device 106. Figure 5 Same as the example, Figure 6 The computer-assisted system of FIG. 5 includes a manipulator arm 120. The manipulator arm includes an instrument 126 having a distal portion 107 (e.g., an end effector) that physically interacts with an environment 500. Depending on the specific application, the environment may include objects with different mechanical properties and / or different non-solid materials, similar to a combination of Figure 4 As described in the embodiments.

[0069] according to Figure 6 In the embodiment of FIG. 1 , two Cartesian directions are shown, representing two translational degrees of freedom of the input device 106 and the manipulator arm 120. That is, both the input device 106 and the manipulator arm 120 may be capable of moving in the x and y directions, such as Figure 6 As shown. In some embodiments, the Cartesian reference frame can be different between the input device 106 and the manipulator arm 120. That is, in the global reference frame, the x-direction of the input device may not be parallel to the x-direction of the manipulator arm. Instead, movement of the input device in the x-direction can be transformed into movement of the manipulator arm in the x-direction based on the local reference frame of the manipulator arm. In some embodiments, in the global reference frame, the Cartesian direction of the input device can be parallel to the Cartesian direction of the manipulator arm, as the present disclosure is not limited in this regard.

[0070] according to Figure 6In some embodiments, the power metric is determined in three non-parallel translational degrees of freedom (e.g., x, y, and z directions) for both the input device 106 and the manipulator arm 120. In other embodiments, power can also be determined in one or more rotational degrees of freedom or any subset of translational and rotational degrees of freedom, as the present disclosure is not so limited. As previously described, the power metric can be determined as the product of a force measurement and a velocity measurement. In some embodiments, the instrument power metric can be determined by projecting the force applied to the input device onto the translational degrees of freedom (or other degrees of freedom) of the input device. In some embodiments, this projection can be accomplished by taking the dot product. The projected force can then be multiplied by the input device velocity in each respective direction to determine the input device power metric matrix. Likewise, the instrument power metric can be determined by projecting the force measured at the instrument onto the translational degrees of freedom (or other degrees of freedom) of the instrument. The projected instrument force can then be multiplied by the instrument velocity in each respective direction to determine the instrument power metric matrix. The net power generation can then be obtained by comparing the input device power matrix and the instrument power matrix, as referenced in Figure 4-Figure 5 As described with reference to FIG. 3, this can be used to determine the damping of the input device. The plurality of values in the matrix can correspond to different degrees of freedom of the input device that are damped. In effect, this process can allow the damping coefficients of virtual dampers to be determined, each virtual damper corresponding to a degree of freedom of the input device. In this way, damping can be applied only in the directions in which the power comparison results in excess power. According to this approach, damping can be applied in an anisotropic manner, where the damping varies along each respective degree of freedom based on the magnitude of the excess power along each respective degree of freedom. When the user operates the input device, damping can be applied only in the directions in which the user’s input device is moving.

[0071] Figure 6 The axes shown in FIG. 3 are exemplary and, in some embodiments, can vary as the instrument environment interaction or input device environment interaction varies. For example, in the example of FIG. 2, if the environment contact direction were rotated 45 degrees about the axis coming straight out of the page, the axes used to determine the power metric and damping could also be rotated 45 degrees about the same axis. Thus, the damping coordinate system can be based on the direction in which force is applied between the instrument and the instrument environment and the input device and the input device environment. Figure 6

[0072] Figure 6 An exemplary instrument power metric and associated virtual dampers corresponding to x and y translational degrees of freedom are depicted. The input device 106 can have one or more additional degrees of freedom, but for simplicity of explanation, only the x and y translational degrees of freedom are shown. Figure 6 The right side of FIG. 3 shows the manipulator “follower” portion. As Figure 6 ​As shown on the right, the distal portion 107 of the instrument 126 is pressed against the environment 500 with a force in the negative y direction, which is opposite to the direction indicated by the arrow P_y. The environment 500 can be a surface perpendicular to the y direction. Figure 6 As shown, the instrument power metric may reflect force and velocity in the y-direction, represented by arrow P_y. However, to simplify the explanation, and based on the force applied by instrument 126 and the movement of instrument 126 being directly in the direction represented by arrow P_y, there is no force applied to the instrument in the x-direction. In this example, the power metric in the x-direction would be a value effectively associated with no power or energy (e.g., "zero" or some other baseline value), and there would be no force applied to the instrument in the x-direction. Figure 6 Shown in. Figure 6 The left side of is shown as the input device "leader" portion. On the input device side, an x-direction damper 103x and a y-direction damper 103y are shown. These dampers may be virtual dampers and represent passive or active forces applied to the input device based on a damping level determined according to the exemplary methods described herein. To simplify the explanation, dampers 103x and 103y are described here as being modeled by pure viscous damping, and in other embodiments, dampers with more complex or nonlinear damping responses may be used. Figure 6 In this example, the x-direction damper 103 has a damping coefficient B_x, and the y-direction damper 103y has a damping coefficient B_y. Figure 6 In the example shown, the device power metric P_y can be "non-zero" and effectively indicate an amount of power or energy that is different from no power or no energy (for example, the power metric P_y can be zero, or a baseline value). The non-zero power metric P_y can result in excess energy, which is used to determine the y-direction damping coefficient B_y. For example, B_y can be set to be proportional to the difference between the device power metric P_y and the corresponding y-direction input device power metric. Therefore, the input device 106 can be damped in the y-direction. Conversely, because the device power metric in the x-direction is zero or less than or equal to the x-direction input device power metric, the x-direction damping coefficient B_x can be set to zero or another baseline value. In this way, damping can be applied to the input device in directions where excess power is generated to avoid instability in force feedback in those directions, while maintaining little or no damping in other stable directions without excess power to avoid hindering the user's feeling in those directions.

[0073] In some embodiments as previously described, the power metric matrix can be integrated or otherwise accumulated over time to obtain an energy matrix. In some implementations, this energy matrix can be employed to determine a plurality of damping coefficients associated with each degree of freedom of the input device. In some embodiments, the damping can be determined from the net energy matrix multiplied by a gain value. Thus, the methods described herein with reference to one or more power matrices can be adapted to employ energy calculations instead.

[0074] It should be noted that while reference is made in the planar example to Figure 6 Two translational degrees of freedom (x and y) are shown and described, but in other embodiments any suitable degrees of freedom can be employed, including any combination of translational and / or rotational degrees of freedom. For example, in some embodiments, power metrics and damping can be determined only in rotational degrees of freedom, rather than translational degrees of freedom as shown. Figure 6

[0075] Figure 7 A plot depicting experimental results for a computer-assisted system in accordance with some example embodiments described herein is shown. In particular, Figure 7 The data shown represent the instrument moving in contact and out of contact with a surface in its environment. In particular, the instrument is moved in contact and out of contact in one direction at a time. Figure 7 The data shown represent a single direction for determining force, power metrics, and damping, however Figure 7 The data in can be extended to multiple directions corresponding to multiple degrees of freedom.

[0076] As previously described, in some embodiments, the method of controlling the computer-assisted system includes limiting the amount of damping applied to the input device. Figure 7 A plot depicting results of a method implementing this technique, which improves user performance feel while allowing increased damping in unstable situations, is shown. In some embodiments, determining the amount of damping to apply to the input device can include limiting the amount of damping to a damping limit. This damping limit is shown in the lower plot. In some embodiments, the damping limit can be static, while in other embodiments the damping limit can be adjusted to accommodate additional damping when appropriate. In some such embodiments, the damping limit can be configured to increase at a rate when the determined amount of damping exceeds a damping threshold. In some cases, the damping threshold and the damping limit can be the same, such that determining the amount of damping to be greater than the imposed damping limit causes the damping limit to increase at the rate. The rate can be a maximum rate configured to limit the speed at which the damping limit increases, thereby eliminating rapid spikes in damping of the input device. In some embodiments, the damping limit can increase proportionally to the determined amount of damping. An example of the damping limit increasing is shown in Figure 7 ​. In the depicted embodiment, the rate at which the damping is limited to increase is a linear slew rate. As the damping limit increases, the amount of damping applied to the input device may also increase. In some embodiments, the damping limit may be limited to a maximum damping limit, which may be determined based on the specific kinematics and application of the computer-assisted system.

[0077] exist Figure 7 In some embodiments shown, the damping limit can also be restored to its original value when additional damping is not needed. In some embodiments, the damping limit can be reduced when the amount of damping is less than the damping limit for a threshold period of time. Figure 7 In the example of , this is shown as the damping limit being reduced when the damping characteristic value drops below the limit. The threshold time period may be any suitable time period, including a period between 0 seconds and 1 second, between 0.01 seconds and 0.1 seconds, between 0.1 seconds and 0.5 seconds, or any other suitable range. In some embodiments, no time period may be employed, and once the amount of damping determined is less than the damping limit, the damping limit may be reduced. In the example of Figure 7 In some of the embodiments shown, the damping limit can be reduced at another rate. That is, the damping limit can be configured to decrease at an upper rate so that the damping limit does not immediately return to its original value. This arrangement can be beneficial in providing stability during periods of time when there may be multiple interactions between the instrument and its environment in rapid succession. Figure 7 In the embodiment of FIG. 5 , the decreasing rate is a linear slew rate, but other arrangements are also envisioned, including exponential decay or other monotonically decreasing rates.

[0078] Figure 8 A flow chart of a method for operating a computer-assisted system according to some embodiments is depicted. In block 600, an instrument power metric is determined that indicates the amount of power of an instrument interaction. The instrument interaction comprises a physical interaction between at least a portion of the instrument (e.g., a distal portion of the instrument, such as an end effector of the instrument) and an instrument environment containing the instrument. In some embodiments, the instrument interaction may comprise interaction with tissue or other objects or non-solid materials, such as interaction with a surface or mass of such objects or solid materials. As previously described, in some embodiments, the power metric may be determined with respect to multiple degrees of freedom, including any subset of the translational and rotational degrees of freedom of the instrument. As previously described, the instrument power metric may represent the energy of the interaction of the instrument with the instrument environment (e.g., instantaneous power measured over a time period, the amount of energy applied or received over the time period). In block 602, an input device power metric is determined that indicates the amount of power of feedback provided by the input device in response to the instrument interaction. In some embodiments, the input device power metric may be determined over multiple degrees of freedom, including any subset of the translational and rotational degrees of freedom of the input device. The input device power metric may be determined, for example, as described with reference to FIG. Figure 4The.

[0079] As Figure 8 shown, in block 604, a damping to be applied to the input device is determined based on the instrument power metric and the input device power metric. For example, in some embodiments, the input device power metric and the instrument power metric are compared. This comparison can result in an excess power metric (e.g., a net energy comparison between input device environmental interactions and instrument environmental interactions) generated by a control loop for the computer-assisted system. This excess power metric can be used to determine the damping. In some embodiments, the damping can be proportional to the excess power. As previously noted, the power metrics can represent energy (e.g., power over a period of time), and in some embodiments, the power can be integrated or summed over time to determine power metrics that can be compared and used to determine the damping applied by the damping system. In block 606, the damping system is caused to apply the determined damping to the input device. In some embodiments, the damping system can include a physical damper, such as a brake, that can be adjusted to apply the determined damping. In other embodiments, the damping system can include or cooperate with an actuator system to apply an active force resisting motion of the input device according to the determined damping. The damping applied in such an arrangement can be incorporated into the total force output commanded to a particular actuator. That is, in some embodiments, the application of damping can be incorporated into the total output force of an actuator. As Figure 8 shown, the method can be repeated as part of a control loop for the computer-assisted system.

[0080] The above-described embodiments of the technology described herein can be implemented in any of various ways. For example, the embodiments can be implemented using hardware, software or a combination thereof. When implemented in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single computer or distributed among multiple computers. Such processors can be implemented as integrated circuits, with one or more processor cores, in circuit boards in a computer or other suitable device, including commercial off-the-shelf (COTS) computer chips, GPUs, microprocessors, microcontrollers, or co-processors. Alternatively, the processors can be implemented in custom circuitry, such as an ASIC, or semicustom circuitry produced by configuring a programmable logic device. As yet another alternative, the processors can be portions of a larger circuit or semiconductor device, whether commercially available, semi-custom or custom. As a specific example, some commercial microprocessors have multiple cores such that one or a subset of those cores can constitute a processor. The processors can be implemented using circuitry in any suitable format.

[0081] Also, it should be appreciated that a computer can be embodied in any of a number of forms, such as a rack-mounted computer, a desktop computer, a laptop computer, or a tablet computer. Additionally, a computer can be embedded in a device not generally regarded as a computer but with suitable processing capabilities, including a Personal Digital Assistant (PDA), a smart phone or any other suitable portable or fixed electronic device.

[0082] Also, a computer can have one or more input and output devices. These devices can be used, among other things, to present computer output to a user. Examples of output devices that can be used to provide user interfaces include printers or display screens for visual presentation of output and speakers or other sound generating devices for audible presentation of output. Examples of input devices that can be used for a user interface include keyboards and pointing devices, such as mice, touch pads, and digitizing tablets. As another example, a computer can receive input information through speech recognition or in other audible formats.

[0083] Such computers can be interconnected by one or more networks in any suitable form, including a local area network or a wide area network, such as an enterprise network or the Internet. Such networks can be based on any suitable technology and can operate according to any suitable protocol and can include wireless networks, wired networks or fiber optic networks.

[0084] Also, various methods or processes outlined herein can be encoded as software that is executable on one or more processors that employ any one of a variety of operating systems or platforms. Additionally, such software can be written in any of a number of suitable programming languages and / or programming or scripting tools, and also can be compiled as executable machine language code or intermediate code that is executed on a framework or virtual machine.

[0085] In this regard, embodiments described herein can embody a computer-readable storage medium (or media) (e.g., a computer memory, one or more floppy discs, compact discs (CD), optical discs, digital video discs (DVD), magnetic tapes, flash memories, circuit configurations in Field Programmable Gate Arrays or other semiconductor devices, or other tangible computer storage medium) encoded with one or more programs that, when executed on one or more computers or other processors, perform methods that implement the various embodiments described above. As will be apparent, the computer-readable storage medium can be a transitory medium, such that the storage medium does not persist for a long duration. As also will be apparent, the computer-readable storage medium can be a non-transitory medium, such that the storage medium does not need to be changed physically to persist for a long duration. The one or more programs can be stored in the computer-readable storage medium at the time of manufacturing, at the time of delivery, or at a later time. The one or more programs can be executable by one or more computers or other processors to perform the methods described above. As will be apparent, the computer-readable storage medium can be a transitory medium, such that the storage medium does not persist for a long duration. As also will be apparent, the computer-readable storage medium can be a non-transitory medium, such that the storage medium does not need to be changed physically to persist for a long duration. The one or more programs can be stored in the computer-readable storage medium at the time of manufacturing, at the time of delivery, or at a later time. The one or more programs can be executable by one or more computers or other processors to perform the methods described above.

[0086] The terms "program" or "software" are used herein in a generic sense to refer to any type of computer code or set of computer-executable instructions that can be employed to program a computer or other processor to implement various aspects of the present disclosure as described above. Additionally, it should be appreciated that according to one aspect of this embodiment, one or more computer programs that when executed perform methods of the present disclosure need not reside on a single computer or processor, but can be distributed in a modular fashion amongst a number of different computers or processors to implement various aspects of the present disclosure.

[0087] Computer-executable instructions can be in many forms, such as program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Typically the functionality of the program modules can be combined or distributed as desired in various embodiments.

[0088] Also, data structures can be stored in computer-readable media in any suitable form. For simplicity of illustration, data structures can be shown to have fields that are related through location in the data structure. Such relationships can likewise be achieved by assigning storage for the fields with locations in a computer-readable medium that conveys relationship between the fields. However, any suitable mechanism can be used to establish a relationship between information in fields of a data structure, including through the use of pointers, tags or other mechanisms that establish relationship between data elements.

[0089] Various aspects of the disclosure can be used alone, in combination, or in various arrangements not specifically discussed herein, and therefore the application should not be limited to the described details and arrangements. For example, aspects described in one embodiment can be combined with aspects described in other embodiments in any manner.

[0090] Furthermore, embodiments described herein can be embodied as a method, of which an example has been provided. The acts performed as part of the method can be ordered in any suitable way. Accordingly, embodiments can be constructed in which acts are performed in an order different than illustrated, which can include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments.

[0091] Furthermore, some actions are described as taken by a "user." It should be understood that a "user" need not be a single individual, and in some embodiments actions caused by a "user" can be performed by a team of individuals and / or individuals in conjunction with computer-aided tools or other mechanisms.

[0092] While the present teachings are described in conjunction with various embodiments and examples, it is not intended that the present teachings be limited to such embodiments or examples. On the contrary, the present teachings encompass various alternatives, modifications, and equivalents. Therefore, the above description and drawings are not exhaustive and are only examples.

Claims

1. A computer-aided system comprising: manipulator arm; an input device configured to accept user commands to move the manipulator arm; a damping system coupled to the input device; as well as A controller comprising at least one processor, the controller being configured to: determining an instrument power metric indicative of an amount of power of an instrument interaction comprising a physical interaction between at least a portion of an instrument and an instrument environment containing the instrument, the instrument being supported by the manipulator arm, determining an input device power metric indicative of an amount of power of feedback provided by the input device in response to the instrument interaction, determining damping to apply to the input device based on the instrument power metric and the input device power metric, and causing the damping system to apply the damping to the input device, The controller is configured to determine the damping by: In response to the input device power metric being greater than or equal to the machine power metric, the amount of damping is set to minimum damping.

2. The computer-assisted system of claim 1 , wherein the controller is configured to further determine the damping by: In response to the input device power metric being less than the machine power metric, the amount of damping is set to a higher damping that is greater than the minimum damping.

3. The computer-assisted system of claim 1 , wherein the controller is configured to determine the damping by: The amount of the damping is limited to a damping limit.

4. The computer-assisted system of claim 3 , wherein the controller is further configured to: In response to determining that the amount of damping is greater than a damping threshold, the damping limit is increased at a first rate.

5. The computer-assisted system of claim 4 , wherein the controller is further configured to: The damping limit is constrained not to exceed a maximum damping limit.

6. The computer-assisted system of claim 4, wherein the controller is further configured to: In response to the amount of damping being less than the damping limit for a threshold period of time, the damping limit is reduced.

7. The computer-assisted system of claim 1 , wherein the controller is configured to cause the damping system to apply the damping to the input device by: causing physical adjustment of an adjustable damper of said damping system; driving an actuator system to apply an active damping force or torque to the input device; or A braking system of the damping system is caused to apply a braking force to the input device.

8. The computer-assisted system of claim 1 , wherein the controller is configured to cause the damping system to apply the damping to the input device by: An actuator system is driven to apply an active damping force or torque to the input device in a direction opposite to the direction of motion of the input device.

9. The computer-assisted system according to claim 1, wherein: The controller is configured to determine the appliance power metric by determining an accumulation of power of the appliance interactions over a period of time; and The controller is configured to determine the input device power metric by determining an accumulation of power of the input device interactions over the time period.

10. The computer-assisted system according to claim 9, wherein: The controller is configured to determine the instrument power metric further by reducing the accumulation of the power of the instrument interactions over time; and The controller is configured to determine the input device power metric further by reducing the accumulation of the power of the input device interactions over the passage of time.

11. The computer-assisted system according to claim 1 , wherein: The controller is configured to determine the instrument power metric by determining at least one product selected from the group consisting of: the product of the translational velocity of the instrument along the instrument's translational degree of freedom and the force applied by the instrument to the instrument's environment in the instrument's translational degree of freedom, and the product of the rotational velocity of the instrument along an instrument rotational degree of freedom and the torque applied by the instrument to the instrument environment in the instrument rotational degree of freedom; and The controller is configured to determine the input device power metric by determining at least one product selected from the group consisting of: the product of the translational velocity of the input device in the input device translational degree of freedom and the force applied by the input device to the input device environment in the input device translational degree of freedom, and The product of the rotational velocity of the input device in the input device rotational degree of freedom and the torque applied by the input device to the input device environment in the input device rotational degree of freedom.

12. The computer-assisted system according to claim 1, wherein: The computer-assisted system is configured to move the instrument in a plurality of instrument degrees of freedom; the input device being configured to move in a plurality of input device degrees of freedom, each degree of freedom of the plurality of input device degrees of freedom corresponding to a degree of freedom of the plurality of instrument degrees of freedom; The controller is configured to determine the instrument power metric by: for each of a plurality of non-parallel instrument degrees of freedom, calculating an instrument power component based on a product of an instrument velocity and an instrument force in the instrument degree of freedom; The controller is configured to determine the input device power metric by: for each of a plurality of input device degrees of freedom, calculating an input device power component based on a product of an input device velocity and an input device force in the input device degree of freedom; and The controller is configured to determine the damping by, for each of the plurality of input device degrees of freedom, determining an amount of damping in the input device degree of freedom based on the input device power component along the input device degree of freedom and the machine power component along the degree of freedom corresponding to the input device degree of freedom.

13. The computer-assisted system according to claim 12, wherein: The plurality of instrument degrees of freedom include a first instrument translation degree of freedom, a second instrument translation degree of freedom, and a third instrument translation degree of freedom; and The plurality of input device degrees of freedom include a first input device translational degree of freedom associated with the first instrument translational degree of freedom, a second input device translational degree of freedom associated with the second instrument translational degree of freedom, and a third input device translational degree of freedom associated with the third instrument translational degree of freedom.

14. A computer-aided system comprising: manipulator arm; an input device configured to accept user commands to move the manipulator arm; a damping system coupled to the input device; as well as A controller comprising at least one processor, the controller being configured to: determining an instrument power metric indicative of an amount of power of an instrument interaction comprising a physical interaction between at least a portion of an instrument and an instrument environment containing the instrument, the instrument being supported by the manipulator arm, determining an input device power metric indicative of an amount of power of feedback provided by the input device in response to the instrument interaction, determining damping to apply to the input device based on the instrument power metric and the input device power metric, and causing the damping system to apply the damping to the input device, Wherein when the apparatus power metric is greater than the input device power metric, an amount of the damping to be applied to the input device has a positive monotonic relationship to the amount by which the apparatus power metric is greater than the input device power metric.

15. The computer-assisted system of claim 14, wherein the positive monotonic relationship is a strictly monotonic relationship.

16. The computer-assisted system of claim 14, wherein the amount by which the apparatus power metric is greater than the input device power metric comprises the amount of the apparatus power metric minus the amount of the input device power metric.

17. The computer-assisted system of claim 14, wherein the controller is configured to determine the damping by: The amount of the damping is limited to a damping limit.

18. The computer-assisted system of claim 17, wherein the controller is further configured to: In response to determining that the amount of damping is greater than a damping threshold, the damping limit is increased at a first rate.

19. The computer-assisted system of claim 18, wherein the controller is further configured to: The damping limit is constrained not to exceed a maximum damping limit.

20. The computer-assisted system of claim 18, wherein the controller is further configured to: In response to the amount of damping being less than the damping limit for a threshold period of time, the damping limit is reduced.

21. The computer-assisted system of claim 14, wherein the controller is configured to cause the damping system to apply the damping to the input device by: causing physical adjustment of an adjustable damper of said damping system; driving an actuator system to apply an active damping force or torque to the input device; or A braking system of the damping system is caused to apply a braking force to the input device.

22. The computer-assisted system of claim 14, wherein the controller is configured to cause the damping system to apply the damping to the input device by: An actuator system is driven to apply an active damping force or torque to the input device in a direction opposite to the direction of motion of the input device.

23. The computer-assisted system of claim 14, wherein: The controller is configured to determine the appliance power metric by determining an accumulation of power of the appliance interactions over a period of time; and The controller is configured to determine the input device power metric by determining an accumulation of power of the input device interactions over the time period.

24. The computer-assisted system of claim 23, wherein: The controller is configured to determine the instrument power metric further by reducing the accumulation of the power of the instrument interactions over time; and The controller is configured to determine the input device power metric further by reducing the accumulation of the power of the input device interactions over the passage of time.

25. The computer-assisted system of claim 14, wherein: The controller is configured to determine the instrument power metric by determining at least one product selected from the group consisting of: the product of the translational velocity of the instrument along the instrument's translational degree of freedom and the force applied by the instrument to the instrument's environment in the instrument's translational degree of freedom, and the product of the rotational velocity of the instrument along an instrument rotational degree of freedom and the torque applied by the instrument to the instrument environment in the instrument rotational degree of freedom; and The controller is configured to determine the input device power metric by determining at least one product selected from the group consisting of: the product of the translational velocity of the input device in the input device translational degree of freedom and the force applied by the input device to the input device environment in the input device translational degree of freedom, and The product of the rotational velocity of the input device in the input device rotational degree of freedom and the torque applied by the input device to the input device environment in the input device rotational degree of freedom.

26. The computer-assisted system of claim 14, wherein: The computer-assisted system is configured to move the instrument in a plurality of instrument degrees of freedom; the input device being configured to move in a plurality of input device degrees of freedom, each degree of freedom of the plurality of input device degrees of freedom corresponding to a degree of freedom of the plurality of instrument degrees of freedom; The controller is configured to determine the instrument power metric by: for each of a plurality of non-parallel instrument degrees of freedom, calculating an instrument power component based on a product of an instrument velocity and an instrument force in the instrument degree of freedom; The controller is configured to determine the input device power metric by: for each of a plurality of input device degrees of freedom, calculating an input device power component based on a product of an input device velocity and an input device force in the input device degree of freedom; and The controller is configured to determine the damping by, for each of the plurality of input device degrees of freedom, determining an amount of damping in the input device degree of freedom based on the input device power component along the input device degree of freedom and the machine power component along the degree of freedom corresponding to the input device degree of freedom.

27. The computer-assisted system of claim 26, wherein: The plurality of instrument degrees of freedom include a first instrument translation degree of freedom, a second instrument translation degree of freedom, and a third instrument translation degree of freedom; and The plurality of input device degrees of freedom include a first input device translational degree of freedom associated with the first instrument translational degree of freedom, a second input device translational degree of freedom associated with the second instrument translational degree of freedom, and a third input device translational degree of freedom associated with the third instrument translational degree of freedom.

28. A computer-aided system comprising: manipulator arm; an input device configured to accept user commands to move the manipulator arm; a damping system coupled to the input device; as well as A controller comprising at least one processor, the controller being configured to: determining an instrument power metric indicative of an amount of power of an instrument interaction comprising a physical interaction between at least a portion of an instrument and an instrument environment containing the instrument, the instrument being supported by the manipulator arm, determining an input device power metric indicative of an amount of power of feedback provided by the input device in response to the instrument interaction, determining damping to apply to the input device based on the instrument power metric and the input device power metric, and causing the damping system to apply the damping to the input device, in: The controller is configured to determine the damping by: A damping coefficient is determined based on a difference between the machine power metric and the input device power metric.

29. The computer-assisted system of claim 28, wherein, if the instrument power metric is greater than the input device power metric, the damping coefficient is proportional to the difference for a first range of differences.

30. The computer-assisted system of claim 29, wherein: When the apparatus power metric is greater than the input device power metric, the damping coefficient is non-proportional to the difference for a second range of the difference, wherein the second range is different from the first range; or Where the apparatus power metric is not greater than the input device power metric, the damping coefficient is non-proportional to the difference for a third range of difference values.

31. The computer-assisted system of claim 28, wherein the controller is configured to determine the damping by: The amount of the damping is limited to a damping limit.

32. The computer-assisted system of claim 31 , wherein the controller is further configured to: In response to determining that the amount of damping is greater than a damping threshold, the damping limit is increased at a first rate.

33. The computer-assisted system of claim 32, wherein the controller is further configured to: The damping limit is constrained not to exceed a maximum damping limit.

34. The computer-assisted system of claim 32, wherein the controller is further configured to: In response to the amount of damping being less than the damping limit for a threshold period of time, the damping limit is reduced.

35. The computer-assisted system of claim 28, wherein the controller is configured to cause the damping system to apply the damping to the input device by: causing physical adjustment of an adjustable damper of said damping system; driving an actuator system to apply an active damping force or torque to the input device; or A braking system of the damping system is caused to apply a braking force to the input device.

36. The computer-assisted system of claim 28, wherein the controller is configured to cause the damping system to apply the damping to the input device by: An actuator system is driven to apply an active damping force or torque to the input device in a direction opposite to the direction of motion of the input device.

37. The computer-assisted system of claim 28, wherein: The controller is configured to determine the appliance power metric by determining an accumulation of power of the appliance interactions over a period of time; and The controller is configured to determine the input device power metric by determining an accumulation of power of the input device interactions over the time period.

38. The computer-assisted system of claim 37, wherein: The controller is configured to determine the instrument power metric further by reducing the accumulation of the power of the instrument interactions over time; and The controller is configured to determine the input device power metric further by reducing the accumulation of the power of the input device interactions over the passage of time.

39. The computer-assisted system of claim 28, wherein: The controller is configured to determine the instrument power metric by determining at least one product selected from the group consisting of: the product of the translational velocity of the instrument along the instrument's translational degree of freedom and the force applied by the instrument to the instrument's environment in the instrument's translational degree of freedom, and the product of the rotational velocity of the instrument along an instrument rotational degree of freedom and the torque applied by the instrument to the instrument environment in the instrument rotational degree of freedom; and The controller is configured to determine the input device power metric by determining at least one product selected from the group consisting of: the product of the translational velocity of the input device in the input device translational degree of freedom and the force applied by the input device to the input device environment in the input device translational degree of freedom, and The product of the rotational velocity of the input device in the input device rotational degree of freedom and the torque applied by the input device to the input device environment in the input device rotational degree of freedom.

40. The computer-assisted system of claim 28, wherein: The computer-assisted system is configured to move the instrument in a plurality of instrument degrees of freedom; the input device being configured to move in a plurality of input device degrees of freedom, each degree of freedom of the plurality of input device degrees of freedom corresponding to a degree of freedom of the plurality of instrument degrees of freedom; The controller is configured to determine the instrument power metric by: for each of a plurality of non-parallel instrument degrees of freedom, calculating an instrument power component based on a product of an instrument velocity and an instrument force in the instrument degree of freedom; The controller is configured to determine the input device power metric by: for each of a plurality of input device degrees of freedom, calculating an input device power component based on a product of an input device velocity and an input device force in the input device degree of freedom; and The controller is configured to determine the damping by, for each of the plurality of input device degrees of freedom, determining an amount of damping in the input device degree of freedom based on the input device power component along the input device degree of freedom and the machine power component along the degree of freedom corresponding to the input device degree of freedom.

41. The computer-assisted system of claim 40, wherein: The plurality of instrument degrees of freedom include a first instrument translation degree of freedom, a second instrument translation degree of freedom, and a third instrument translation degree of freedom; and The plurality of input device degrees of freedom include a first input device translational degree of freedom associated with the first instrument translational degree of freedom, a second input device translational degree of freedom associated with the second instrument translational degree of freedom, and a third input device translational degree of freedom associated with the third instrument translational degree of freedom.

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