Method and circuit for monitoring protective ground continuity in a medical device using a lock-in amplifier

Abstract

The robotic system may include a ground line and a protective ground conductor electrically coupled to the ground line. The robotic system may also include a test circuit coupled to the protective ground conductor through an isolation capacitor. The test circuit may include a lock-in amplifier and may be configured to measure an impedance for the protective ground conductor through the isolation capacitor. Methods for testing or monitoring the protective ground conductor are also disclosed herein.

Description

[Technical field]

[0001] The systems and methods disclosed herein are directed to systems having a protective earth connection, and more particularly to medical systems having a protective earth connection. [Background technology]

[0002] Robot-enabled medical systems can perform a variety of medical procedures, including both minimally invasive procedures, such as laparoscopy, and non-invasive procedures, such as endoscopy (e.g., bronchoscopy, ureteroscopy, gastroscopy, etc.). Such robotic medical systems may include a metal enclosure and a robotic arm configured to control the movement of a medical tool during a given medical procedure. Summary of the Invention [Means for solving the problem]

[0003] The systems, methods, and devices of the present disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.

[0004] Medical devices with metal enclosures require a functional protective-earth (PE) connection to protect patients and operators from receiving electric shocks. To achieve a functional PE connection, the metal enclosure can be connected to a ground (GND) line.

[0005] In particular, for medical devices with few connections between the metal enclosure and the GND line, it may be beneficial to have a means to test the PE connection during the life of the medical device to detect whether the PE connection has degraded over time. However, testing the PE connection during the life of the medical device may be difficult. First, applying a test current to the metal enclosure may pose a shock hazard if the test current is not maintained at a low level (e.g., less than 100 microamps, or less than 50 microamps). Second, the PE connection between the metal enclosure and the GND line may have a low impedance (e.g., less than 1 ohm), and therefore the power to apply the test current may also be low (e.g., less than 100 microvolts), and therefore difficult to detect and measure. Third, the PE connection may be subject to electromagnetic interference, which increases noise and makes measuring small signals more difficult.

[0006] In one aspect, the robotic system includes a ground line and a protective ground conductor electrically coupled to the ground line at a first point. The robotic system further includes a test circuit (sometimes referred to as a monitoring circuit) coupled to the protective ground conductor at a second point through an isolation capacitor. The test circuit includes a lock-in amplifier and is configured to measure an impedance for the protective ground conductor.

[0007] In another aspect, a robotic system includes a ground line, a protective ground conductor, and a test circuit coupled to the protective ground conductor via an isolation capacitor and configured to measure an impedance of the ground line with respect to the protective ground conductor through the isolation capacitor.

[0008] In another aspect, a robotic system includes a ground line, a protective ground conductor, and a test circuit coupled to the protective ground conductor and configured to measure an impedance of the ground line relative to the protective ground conductor.

[0009] In another aspect, a method for testing a protective ground conductor includes applying a test signal through (or to) an isolation capacitor electrically coupled to the protective ground conductor and acquiring a signal from the protective ground conductor via the isolation capacitor in response to the test signal. The method also includes measuring an impedance for the protective ground conductor based on the acquired signal, where the measuring is performed by a lock-in amplifier, comparing the determined impedance to a baseline impedance, and providing information indicative of a result of the comparison. In some embodiments, the method is performed by one or more processors implementing instructions stored in a memory.

[0010] In yet another aspect, a method for testing a protective ground conductor includes providing a test current through an isolation capacitor electrically coupled to the protective ground conductor and acquiring a voltage signal across the isolation capacitor in response to the test current. The method also includes measuring an impedance for the protective ground conductor based on the acquired voltage signal, and providing information indicative of continuity of the protective ground conductor based on the measured impedance. In some embodiments, the method is performed by one or more processors implementing instructions stored in a memory.

[0011] It should be noted that the various embodiments described above can be combined with any other embodiment described herein. The features and advantages described herein are not all-inclusive, and in particular many additional features and advantages will be apparent to those skilled in the art upon consideration of the drawings, specification, and claims. Furthermore, it should be noted that the language used in this specification has been selected primarily for readability and instructional purposes, and may not be selected to delineate or limit the subject matter of the present invention. [Brief description of the drawings]

[0012] The disclosed aspects are hereinafter described in conjunction with the accompanying drawings, which illustrate, but do not limit, the disclosed aspects, and in which like designations refer to like elements and in which: [Figure 1] FIG. 1 illustrates one embodiment of a cart-based robotic system positioned for a diagnostic and / or therapeutic bronchoscopic procedure, according to some embodiments. [Diagram 2] FIG. 2 depicts further aspects of the robotic system of FIG. 1, according to some embodiments. [Diagram 3] FIG. 2 illustrates an embodiment of the robotic system of FIG. 1 positioned for ureteroscopy, according to some embodiments. [Figure 4] FIG. 2 illustrates an embodiment of the robotic system of FIG. 1 positioned for a vascular procedure, according to some embodiments. [Diagram 5] FIG. 1 illustrates one embodiment of a table-based robotic system positioned for a bronchoscopic procedure, according to some embodiments. [Figure 6] FIG. 1 illustrates an example system configured to accommodate a robotic arm, according to some implementations. [Figure 7] FIG. 1 illustrates an alternative embodiment of a table-based robotic system, according to some embodiments. [Figure 8] FIG. 8 is an end view of the table-based robotic system of FIG. 7, in accordance with some embodiments. [Figure 9] FIG. 1 illustrates an end view of a table-based robotic system with an attached robotic arm, according to some embodiments. [Figure 10] 1 illustrates an exemplary instrument driver, according to some embodiments. [Figure 11] 1 illustrates an exemplary medical instrument having paired instrument drivers, according to some embodiments. [Figure 12] 14A-14C illustrate an alternative design for the instrument driver and instrument, where the axis of the drive unit is parallel to the axis of the elongated shaft of the instrument, according to some embodiments. [Figure 13] 1 illustrates an instrument having an instrument-based insertion architecture, according to some embodiments. [Figure 14] FIG. 2 illustrates an example controller, according to some embodiments. [Figure 15A] FIG. 1 illustrates an exemplary protective earth system, according to some embodiments. [Figure 15B] FIG. 1 illustrates an exemplary protective earth system, according to some embodiments. [Figure 15C] FIG. 1 illustrates an exemplary protective earth system, according to some embodiments. [Figure 16] FIG. 2 illustrates an example test circuit for a protective earth system, according to some embodiments. [Figure 17A] FIG. 1 illustrates an additional exemplary protective grounding system, according to some embodiments. [Figure 17B] FIG. 1 illustrates an additional exemplary protective grounding system, according to some embodiments. [Figure 18] FIG. 1 illustrates an exemplary robotic arm having a protective grounding system, according to some embodiments. [Figure 19] 1 is a flowchart illustrating an example method for testing a protective ground conductor of a robotic system, according to some embodiments. [Figure 20] FIG. 2 is a schematic diagram illustrating electronic components of a medical system, according to some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] 1. Overview. Aspects of the present disclosure may be integrated into a robot-enabled medical system capable of performing a variety of medical procedures, including both minimally invasive procedures such as laparoscopy, and non-invasive procedures such as endoscopy. Among endoscopic procedures, the system may perform bronchoscopy, ureteroscopy, gastroscopy, etc.

[0014] In addition to performing a wide range of procedures, the system may provide additional benefits such as enhanced imaging and guidance to assist the physician. Furthermore, the system may provide the physician with the ability to perform procedures with improved ease of use, such that a single user may control one or more of the instruments of the system.

[0015] Various embodiments are described below, by way of example only, in conjunction with the drawings, and it will be appreciated that many other implementations of the concepts of the present disclosure are possible, and various advantages may be achieved by implementations of the present disclosure.

[0016] A. Robotic System - Cart. A robot-enabled medical system may be configured in a variety of ways depending on the particular procedure. FIG. 1 illustrates one embodiment of a cart-based robot-enabled system 10 arranged for diagnostic and / or therapeutic bronchoscopy procedures. During bronchoscopy, the system 10 may include a cart 11 having one or more robotic arms 12 for delivering medical instruments, such as a steerable endoscope 13, which may be a procedure-specific bronchoscope for bronchoscopy, to a natural orifice access point (i.e., the mouth of a patient positioned on a table in this example) for delivering diagnostic and / or therapeutic tools. As shown, the cart 11 may be positioned adjacent to the patient's upper torso to provide access to the access point. Similarly, the robotic arms 12 may be actuated to position a bronchoscope relative to the access point. The arrangement of FIG. 1 may also be utilized when performing gastro-intestinal (GI) procedures using a gastroscope. FIG. 2 depicts an example embodiment of the cart in more detail.

[0017] With continued reference to FIG. 1, once the cart 11 is properly positioned, the robotic arm 12 can insert the steerable endoscope 13 into the patient robotically, manually, or a combination thereof. As shown, the steerable endoscope 13 can include at least two nested parts, such as an inner leader section and an outer sheath section, each section coupled to a separate instrument driver from a set of instrument drivers 28, each instrument driver coupled to the distal end of an individual robotic arm. This linear arrangement of the instrument drivers 28, which facilitates coaxial alignment of the leader section with the sheath section, creates a "virtual rail" 29 that can be repositioned in space by manipulating one or more robotic arms 12 to different angles and / or positions. The virtual rails described herein are depicted in the figures using dashed lines (as in FIGS. 3 and 4), and thus the dashed lines do not depict any physical structure of the system. Translation of the instrument driver 28 along the virtual rail 29 nests the inner leader section relative to the outer sheath section, or advances or retracts the endoscope 13 from the patient. The angle of the virtual rail 29 may be adjusted, translated, or pivoted based on clinical application or physician preference. For example, in bronchoscopy, the angle and position of the virtual rail 29 shown represents a compromise between providing the physician access to the endoscope 13 and minimizing friction that results from bending the endoscope 13 into the patient's mouth.

[0018] The endoscope 13 can be directed downstream of the patient's trachea and lungs after insertion using precise commands from the robotic system until the target destination or surgical site is reached. The endoscope 13 can be manipulated to telescope the inner leader portion from the outer sheath portion to enhance articulation and increase bend radius to enhance navigation through the patient's pulmonary network and / or reach a desired target. The use of a separate instrument driver 28 also allows the leader and sheath portions to be driven independently of one another.

[0019] For example, the endoscope 13 may be oriented to deliver a biopsy needle to a target, such as a lesion or nodule in the patient's lung. The needle may be positioned downstream of the working channel along the length of the endoscope to obtain a tissue sample that is analyzed by a pathologist. Depending on the results of the pathology, additional tools may be positioned downstream of the working channel of the endoscope for further biopsies. After identifying the nodule as malignant, the endoscope 13 may endoscopically deliver a tool to ablate the potential cancerous tissue. In some cases, the diagnostic and therapeutic treatments may be delivered in separate procedures. In other cases, the diagnostic and therapeutic treatments may be delivered during the same procedure.

[0020] The system 10 may also include a movable tower 30 that may be connected to the cart 11 via a support cable and provide support for control, electronics, fluidics, optics, sensors, and / or power to the cart 11.

[0021] To support the robotic system described above, the tower 30 may include computer-based control system components that store computer program instructions in a non-transitory computer-readable storage medium, such as, for example, a persistent magnetic storage drive, a solid-state drive, or the like. Execution of these instructions, whether execution occurs in the tower 30 or in the cart 11, may control the entire system or subsystems thereof. For example, when executed by a processor in the computer system, the instructions may cause the robotic system components to actuate associated carriages and arm mounts, operate the robotic arm, and control medical instruments. For example, in response to receiving control signals, motors in the joints of the robotic arm may position the arm in a particular pose.

[0022] The tower 30 may also include pumps, flow meters, valve controls, and / or fluid access to provide controlled irrigation and aspiration capabilities to a system that may be deployed through the endoscope 13. These components may also be controlled using the computer system of the tower 30. In some embodiments, irrigation and aspiration capabilities may be provided directly to the endoscope 13 via separate cables.

[0023] The tower 30 may also include support equipment for sensors located throughout the robotic system 10. For example, the tower 30 may include optoelectronic equipment for detecting, receiving, and processing data received from optical sensors or cameras anywhere in the robotic system 10. In combination with a control system, such optoelectronic equipment may be used to generate real-time images for display in any number of consoles located throughout the system, including in the tower 30. Similarly, the tower 30 may also include electronic subsystems for receiving signals from and processing received electromagnetic (EM) sensors located therein. The tower 30 may also be used to house and position EM field generators for detection by EM sensors in or on the medical instrument.

[0024] The tower 30 may also include a console 31 in addition to other consoles available to the rest of the system, for example a console mounted on top of a cart. The console 31 may include a user interface and a display screen, such as a touch screen, for the operator physician. The consoles in the system 10 are generally designed to provide both pre-operative and real-time information of the procedure, such as robotic control and navigation and localization information for the endoscope 13. If the console 31 is not the only console available to the physician, the console 31 may be used by a second operator, such as a nurse, to provide procedure-specific data, such as navigation and localization information, as well as monitor the patient's health or vitals and the operation of the system 10. In other embodiments, the console 31 is housed in a body separate from the tower 30.

[0025] FIG. 2 provides a detailed view of one embodiment of a cart 11 from the cart-based robot-enabled system shown in FIG. 1. The cart 11 generally includes an elongated support structure 14 (often referred to as a "column"), a cart base 15, and a console 16 at the top of the column 14. The column 14 may include one or more carriages, such as a carriage 17 (alternatively an "arm support") for supporting the deployment of one or more robotic arms 12 (three are shown in FIG. 2). The carriage 17 may include individually configurable arm mounts that rotate along orthogonal axes to adjust the base of the robotic arms 12 for better positioning relative to the patient. The carriage 17 also includes a carriage interface 19 that allows the carriage 17 to translate vertically along the column 14.

[0026] The carriage interface 19 is connected to the column 14 through slots, such as slots 20 positioned on either side of the column 14 to guide the vertical translation of the carriage 17. The slots 20 include vertical translation interfaces for positioning and holding the carriage 17 at various vertical heights relative to the cart base 15. The vertical translation of the carriage 17 allows the cart 11 to adjust the reach of the robotic arm 12 to meet various table heights, patient sizes, and physician preferences. Similarly, an individually configurable arm mount on the carriage 17 allows the robotic arm base 21 of the robotic arm 12 to be angled in various configurations.

[0027] Column 14 may contain mechanisms therein, such as gears and motors, designed to use a vertically aligned leadscrew to mechanically translate carriage 17 in response to control signals generated in response to user input, such as input from console 16.

[0028] The robotic arm 12 may generally include a robotic arm base 21 and an end effector 22 separated by a series of links 23 connected by a series of joints 24, each joint including an independent actuator, each actuator including an independently controllable motor. Each independently controllable joint represents an independent degree of freedom available to the robotic arm 12. Each of the robotic arms 12 may have seven joints, thus providing seven degrees of freedom. A large number of joints provides a large number of degrees of freedom, allowing for "redundant" degrees of freedom. Redundant degrees of freedom allow the robotic arm 12 to position its respective end effector 22 at a specific position, orientation, and trajectory in space using different link positions and joint angles. This allows the system to position and orient the medical instrument from a desired point in space, while allowing the physician to move the arm joints to a clinically advantageous position away from the patient to create greater access while avoiding arm collisions.

[0029] The cart base 15 balances the weight of the column 14, carriage 17, and robotic arm 12 on the floor. Thus, the cart base 15 houses the heavier parts such as electronics, motors, power supplies, and components that allow the cart 11 to be either mobile and / or immobilized. For example, the cart base 15 includes casters 25 in the form of rollable wheels that allow the cart 11 to be easily moved around the room before a procedure. After reaching the proper position, the casters 25 can be immobilized using wheel locks to hold the cart 11 in place during a procedure.

[0030] A console 16 positioned at the vertical end of column 14 allows for both a user interface and a display screen (or dual-purpose device such as, for example, a touch screen 26) to receive user input and provide both pre-operative and intra-operative data to the physician user. Potential pre-operative data on the touch screen 26 may include pre-operative planning, navigation and mapping data derived from a pre-operative computed tomography (CT scan), and / or notes from a pre-operative patient interview. Intra-operative data on the display may also include vital patient statistics such as respiration, heart rate, and / or pulse, along with optical information provided from tools, sensor information from sensors, and coordinate information.

[0031] 3 illustrates one embodiment of the robot-enabled system 10 positioned for ureteroscopy. In a ureteroscopy procedure, the cart 11 can be positioned to deliver a ureteroscope 32, a procedure-specific endoscope designed to follow the patient's urethra and ureters, to the patient's lower abdominal region. As shown, the cart 11 can be aligned to a table leg to allow the robotic arm 12 to position the ureteroscope 32 for direct linear access to the patient's urethra. From the table leg, the robotic arm 12 can insert the ureteroscope 32 along a virtual rail 33 directly through the urethra and into the patient's lower abdomen.

[0032] After insertion into the urethra using control techniques similar to those in bronchoscopy, the ureteroscope 32 can be navigated to the bladder, ureters, and / or kidneys for diagnostic and / or therapeutic applications. For example, the ureteroscope 32 can be directed to the ureter and kidney to fragment formed kidney stones using a laser lithotriptor or ultrasonic lithotriptor device positioned downstream of the working channel of the ureteroscope 32. After lithotripsy is complete, the resulting stone fragments can be removed using a basket that deploys downstream of the ureteroscope 32.

[0033] FIG. 4 illustrates an embodiment of the robot-enabled system 10 similarly positioned for a vascular procedure. In a vascular procedure, the system 10 may be configured such that the cart 11 can deliver a medical instrument 34, such as a steerable catheter, to an access point in the femoral artery in the patient's leg. As in a ureteroscopy procedure, the cart 11 may be positioned toward the patient's leg and lower abdomen to enable the robotic arm 12 to provide a virtual rail 35 with direct linear access to the femoral artery access point in the patient's thigh / hip region. After insertion into the artery, the medical instrument 34 may be oriented and inserted by translating the instrument driver 28. Alternatively, the cart may be positioned around the patient's upper abdomen to reach alternative vascular access points, such as the carotid and brachial arteries near the shoulder and wrist.

[0034] B. Robot system-table. An embodiment of a robot-enabled medical system may also incorporate a patient table. Incorporating a table may reduce the amount of capital equipment in the operating room by removing carts, thereby allowing better access to the patient. FIG. 5 illustrates one embodiment of such a robot-enabled system deployed for a bronchoscopy procedure. The system 36 includes a support structure or column 37 for supporting a platform 38 (shown as a "table" or "bed") above the overall floor. Much like a cart-based system, the end effector of the robotic arm 39 of the system 36 includes an instrument driver 42 that is designed to manipulate an elongated medical instrument, such as the bronchoscope 40 of FIG. 5, through or along a virtual rail 41 formed from the linear alignment of the instrument driver 42. In practice, a C-arm for providing fluoroscopic imaging may be positioned above the upper abdominal region of the patient by placing emitters and detectors around the table 38.

[0035] As shown, the column 37 may include one or more carriages 43, shown in the system 36 as ring-shaped, that may be the base for one or more robotic arms 39. The carriages 43 may translate along a vertical column interface 44 that extends the length of the column 37 to provide different vantage points from which the robotic arms 39 may be positioned to reach the patient. The carriages 43 may rotate about the column 37 using a mechanical motor positioned within the column 37 to allow the robotic arms 39 to access multiple sides of the table 38, e.g., both sides of the patient.

[0036] The system 36 may also include a tower (not shown) that divides the functionality of the system 36 between the table and the tower to reduce the form factor and bulk of the table. As with the previously disclosed embodiments, the tower may provide various support functions to the table, such as processing, computing, and control capabilities, power, fluidics, and / or optical and sensor processing. The tower may also be mobile so that it can be positioned away from the patient to improve physician access and keep the operating room clutter-free. The tower may also include a master controller or console that provides both a user interface for user input, such as a keyboard and / or pendant, and a display screen (or touch screen) for pre-operative and intra-operative information, such as real-time imaging, navigation, and tracking information. In some embodiments, the tower may also include a holder for a gas tank used for venting.

[0037] In some embodiments, the table base may house and store the robot arm when not in use. Figure 6 illustrates a system 47 for housing the robot arm in one embodiment of a table-based system. In system 47, carriage 48 may be translated vertically into base 49 to house robot arm 50, arm mount 51, and carriage 48 therein. Base cover 52 may be translated and retracted open to allow carriage 48, arm mount 51, and arm 50 to deploy about column 53, and base cover 52 may be closed to house and protect them when not in use.

[0038] 7 and 8 illustrate isometric and end views of an embodiment of a table-based surgical robotic system 100. The surgical robotic system 100 includes one or more adjustable arm supports 105 that can be configured to support one or more robotic arms relative to a table 101 (see, e.g., FIG. 9). In the illustrated embodiment, only one adjustable arm support 105 is shown, but additional arm supports can be provided on the opposite side of the table 101. The adjustable arm support 105 can be configured to move relative to the table 101 to adjust and / or change the position of the adjustable arm support 105 and / or any robotic arm attached thereto relative to the table 101. For example, the adjustable arm support 105 can be adjusted with one or more degrees of freedom relative to the table 101. The adjustable arm support 105 provides the system 100 with great versatility, including the ability to easily accommodate one or more adjustable arm supports 105 and any robotic arms attached thereto under the table 101. The adjustable arm support 105 can be raised from a stowed position to a position below the top surface of the table 101. In other embodiments, the adjustable arm support 105 can be raised from a stowed position to a position above the top surface of the table 101.

[0039] The adjustable arm support 105 can provide several degrees of freedom, including lift, lateral translation, tilt, etc. In the illustrated embodiment of Figures 7 and 8, the arm support 105 is configured with four degrees of freedom, which are indicated by arrows in Figure 7. The first degree of freedom allows adjustment of the adjustable arm support 105 in the z-direction ("Z-lift"). For example, the adjustable arm support 105 can include a carriage 109 configured to move up and down along or relative to the column 102 that supports the table 101. The second degree of freedom can allow the adjustable arm support 105 to tilt. For example, the adjustable arm support 105 can include a rotational joint, which can allow the adjustable arm support 105 to align with the bed in the Trendelenburg position. The third degree of freedom allows the adjustable arm support 105 to "pivot up," which can be used to adjust the distance between the side of the table 101 and the adjustable arm support 105. A fourth degree of freedom may allow translation of the adjustable arm support 105 along the longitudinal length of the table.

[0040] The surgical robotic system 100 of Figures 7 and 8 can include a table supported by a column 102 mounted to a base 103. The base 103 and column 102 support the table 101 against a support surface. A bed axis 131 and a support axis 133 are shown in Figure 8.

[0041] An adjustable arm support 105 can be mounted to the column 102. In other embodiments, the arm support 105 can be mounted to the table 101 or the base 103. The adjustable arm support 105 can include a carriage 109, a bar or rail connector 111, and a bar or rail 107. In some embodiments, one or more robot arms mounted to the rail 107 can translate and move relative to each other.

[0042] 9 illustrates an end view of a surgical robotic system 140A with two adjustable arm supports 105A, 105B mounted on either side of a table 101. A first robotic arm 142A is attached to a bar or rail 107A of the first adjustable arm support 105B. The first robotic arm 142A includes a base 144A attached to the rail 107A. The distal end of the first robotic arm 142A includes an instrument drive mechanism 146A that can be attached to one or more robotic medical instruments or tools. Similarly, the second robotic arm 142B includes a base 144B attached to the rail 107B. The distal end of the second robotic arm 142B includes an instrument drive mechanism 146B. The instrument drive mechanism 146B can be configured to attach to one or more robotic medical instruments or tools.

[0043] In some embodiments, one or more of the robotic arms 142A, 142B comprise arms with seven or more degrees of freedom. In some embodiments, one or more of the robotic arms 142A, 142B can include eight degrees of freedom, including an insertion axis (one degree of freedom including insertion), wrist (three degrees of freedom including wrist pitch, yaw and roll), elbow (one degree of freedom including elbow pitch), shoulder (two degrees of freedom including shoulder pitch and yaw), and base 144A, 144B (one degree of freedom including translation). In some embodiments, the insertion degree of freedom can be provided by the robotic arms 142A, 142B, while in other embodiments, the instrument itself provides the insertion via an instrument-based insertion architecture.

[0044] C. Instrument drivers and interfaces. The end effector of the robotic arm of the system comprises (i) an instrument driver (alternatively called an "instrument drive mechanism" or "instrument device manipulator") incorporating electromechanical means for actuating the medical instrument, and (ii) a removable or detachable medical instrument, which may not include electromechanical components such as motors. This dichotomy may be caused by the need to sterilize the medical instruments used in the medical procedure and the inability to adequately sterilize expensive capital equipment due to the complex mechanical assembly and sensitive electronics of the medical instruments. Thus, the medical instruments may be designed to be detached, removed, and replaced from the instrument driver (and thus the system) by the physician or the physician's staff for individual sterilization or disposal. In contrast, the instrument driver does not need to be replaced or sterilized and may be draped for protection.

[0045] FIG. 10 illustrates an exemplary instrument driver. The instrument driver 162, positioned at the distal end of the robotic arm, is composed of one or more drive units 163 arranged on parallel shafts to provide a controlled torque to the medical instrument via a drive shaft 164. Each drive unit 163 includes an individual drive shaft 164 for interacting with the instrument, a gearhead 165 for converting motor shaft rotation to a desired torque, a motor 166 for generating the drive torque, an encoder 167 for measuring the speed of the motor shaft and providing feedback to the control circuitry, and a control circuit 168 for receiving control signals to operate the drive unit. Each drive unit 163 is controlled and motorized independently of the others, and the instrument driver 162 may provide multiple (four shown in FIG. 11) independent drive outputs to the medical instrument. In operation, the control circuit 168 will receive the control signals and send motor signals to the motors 166, compare the resulting motor speed as measured by the encoders 167 to a desired speed, and modulate the motor signals to generate the desired torque.

[0046] In procedures requiring a sterile environment, the robotic system can incorporate a drive joint, such as a sterile adapter connected to a sterile drape, located between the instrument driver and the medical instrument. The primary purpose of the sterile adapter is to transfer angular motion from the drive shaft of the instrument driver to the drive input of the instrument while maintaining physical separation between the drive shaft and the drive input, and thus sterility. Thus, an exemplary sterile adapter may include a set of rotational inputs and outputs intended to mate with the drive shaft of the instrument driver and a drive input for the instrument. The sterile drape, which is connected to the sterile adapter, is composed of a thin flexible material, such as a clear or translucent plastic, and is designed to cover the instrument driver, the robot arm, and capital equipment, such as a cart (in a cart-based system) or a table (in a table-based system). The use of the drape allows the capital equipment to be positioned in close proximity to the patient while still being located in an area that does not require sterility (i.e., the non-sterile field). On the other side of the sterile drape, the medical instrument can interact with the patient in an area that requires sterility (i.e., the sterile field).

[0047] D. Medical equipment. 11 illustrates an exemplary medical instrument with a mated instrument driver. Similar to other instruments designed for use with a robotic system, the medical instrument 170 includes an elongated shaft 171 (or elongated body) and an instrument base 172. The instrument base 172, also referred to as an "instrument handle" due to its design intended for manual interaction by a physician, may include a rotary drive input 173, e.g., a receptacle, pulley, or spool, designed to mate with a drive output 174 that passes through a drive interface on an instrument driver 175, typically at the distal end of a robotic arm 176. When physically connected, latched, and / or coupled, the mating drive input 173 of the instrument base 172 may share an axis of rotation with the drive output 174 in the instrument driver 175 to enable the transfer of torque from the drive output 174 to the drive input 173. In some embodiments, the drive output 174 may include a spline designed to mate with a receptacle on the drive input 173.

[0048] The elongated shaft 171 is designed to be delivered through either an anatomical opening or lumen, such as in an endoscope, or a minimally invasive incision, such as in a laparoscopy. The elongated shaft 171 can be either flexible (e.g., having properties similar to an endoscope) or rigid (e.g., having properties similar to a laparoscope), or can include a customized combination of both flexible and rigid portions. If designed for laparoscopy, the distal end of the rigid elongated shaft can be connected to an end effector extending from an articulating wrist formed from a clevis having at least one degree of freedom, and to a surgical tool or medical instrument, such as a grasper or scissors, that can be actuated based on a force from a tendon as the drive input rotates in response to a torque received from the drive output 174 of the instrument driver 175. If designed for endoscopy, the distal end of the flexible elongated shaft can include a steerable or controllable bend that can be articulated and bent based on a torque received from the drive output 174 of the instrument driver 175.

[0049] Torque from the instrument driver 175 is transferred downstream of the elongated shaft 171 using tendons along the shaft 171. These individual tendons, such as pull wires, can be individually secured to individual drive inputs 173 in the instrument handle 172. From the handle 172, the tendons pass along the elongated shaft 171 through one or more pull lumens and are secured to a distal portion of the elongated shaft 171 or are secured to a wrist at the distal portion of the elongated shaft. During a surgical procedure, such as a laparoscopic, endoscopic, or hybrid procedure, these tendons can be coupled to a distally mounted end effector, such as a wrist, grasper, or scissors. In such an arrangement, torque exerted on the drive input 173 will transmit tension to the tendons, thereby actuating the end effector in some manner. In some embodiments, the tendons can rotate a joint about an axis to move the end effector in one direction or another during a surgical procedure. Alternatively, the tendon may be connected to one or more jaws of a grasper at the distal end of the elongate shaft 171, which closes under tension from the tendon.

[0050] In endoscopy, the tendons may be coupled to a bending or articulating section positioned along (e.g., at the distal end) of the elongate shaft 171 via adhesive, control rings, or other mechanical fixation. When fixedly attached to the distal end of the bending section, torque exerted on the drive input 173 is transferred to the tendons, causing the softer bending section (sometimes referred to as the articulating section or area) to bend or articulate. Along the non-bending section, it may be convenient to helical or spiral the individual pull lumens that direct the individual tendons along (or inwardly) the wall of the endoscope shaft to counterbalance the radial forces resulting from tension in the pull wires. The angle of the helix and / or spacing between them may be altered or designed for a particular purpose, with narrower helices exhibiting poor shaft compression under load forces, while fewer helices provide better shaft compression under load forces, but also limited bending. At the other end of the spectrum, the pull lumen can be oriented parallel to the longitudinal axis of the elongate shaft 171 to allow for controlled articulation at the desired bend or articulation.

[0051] In endoscopy, the elongated shaft 171 houses several components that aid in robotic procedures. The elongated shaft may be configured with a working channel for placement of surgical tools (or medical instruments), irrigation, and / or suction at the surgical site at the distal end of the shaft 171. The elongated shaft 171 may also house wires and / or optical fibers that carry signals to / from an optical assembly at the distal tip, which may include an optical camera. The shaft 171 may also house optical fibers for carrying light from a proximally located light source, such as a light emitting diode, to the distal end of the shaft.

[0052] At the distal end of the instrument 170, the distal tip may include a working channel opening for delivering tools to the surgical site for diagnosis and / or treatment, irrigation, and aspiration. The distal tip may also include a port for a camera, such as a fiberscope or digital camera, to capture images of the internal anatomical space. In this regard, the distal tip may also include a port for a light source to illuminate the anatomical space when the camera is in use.

[0053] In the embodiment of FIG. 11, the drive shaft axis, and therefore the drive input axis, is perpendicular to the axis of the elongate shaft.

[0054] FIG. 12 illustrates an alternative design of the instrument driver and instrument, in which the axis of the drive unit is parallel to the axis of the elongated shaft of the instrument. As shown, a circular instrument driver 180 includes four drive units with their drive outputs 181 aligned in parallel at the end of a robotic arm 182. The drive units and their respective drive outputs 181 are housed in a rotating assembly 183 of the instrument driver 180, which is driven by one of the drive units in that assembly 183. In response to torque provided by the rotating drive units, the rotating assembly 183 rotates along a circular bearing connecting the rotating assembly 183 to a non-rotating portion 184 of the instrument driver. In other embodiments, the rotating assembly 183 may be integrated into the non-rotatable portion 184 and thus responsive to a separate drive unit that is not parallel to the other drive units. The rotating mechanism 183 enables the instrument driver 180 to rotate the drive units and their respective drive outputs 181 as a single unit about the instrument driver axis 185.

[0055] Similar to the previously disclosed embodiments, the instrument 186 may include an elongated shaft portion 188 and an instrument base 187 (shown with a transparent exterior skin for purposes of discussion) that includes a number of drive inputs 189 (such as receptacles, pulleys, and spools) configured to receive the drive output 181 in the instrument driver 180. Unlike the previously disclosed embodiments, the instrument shaft 188 extends from the center of the instrument base 187 with its axis being substantially parallel to the axis of the drive input 189, rather than orthogonal as seen in the design of FIG.

[0056] When coupled to the rotation assembly 183 of the instrument driver 180, a medical instrument 186, including an instrument base 187 and an instrument shaft 188, rotates with the rotation assembly 183 about the instrument driver axis 185. Because the instrument shaft 188 is positioned in the center of the instrument base 187, the instrument shaft 188 is coaxial with the instrument driver axis 185 when attached. Thus, rotation of the rotation assembly 183 causes the instrument shaft 188 to rotate about its own longitudinal axis.

[0057] 13 illustrates an instrument having an instrument-based insertion architecture, according to some embodiments. The instrument 200 can be coupled to any of the instrument drivers discussed above. The instrument 200 comprises an elongate shaft 202, an end effector 212 connected to the elongate shaft 202, and a handle 220 coupled to the elongate shaft 202. The elongate shaft 202 includes a tubular member having a proximal portion 204 and a distal portion 206. Manipulation of one or more cables 230a (e.g., via the instrument driver) results in actuation of the end effector 212.

[0058] The instrument handle 220, sometimes referred to as the instrument base, may typically include a mounting interface 222 having one or more mechanical inputs 224, such as receptacles, pulleys or spools, designed to intermate with one or more torque couplers on the mounting surface of the instrument driver.

[0059] In some embodiments, instrument 200 comprises a series of pulleys or cables that allow elongate shaft 202 to translate relative to handle 220. In other words, instrument 200 itself includes an instrument-based insertion architecture that accommodates the insertion of the instrument, thereby effecting insertion of instrument 200 with minimal reliance on a robotic arm. In other embodiments, the robotic arm may be significantly involved in the insertion of the instrument.

[0060] E. Controller. Any of the robotic systems described herein can include an input device or controller for manipulating an instrument attached to the robotic arm. In some embodiments, the instrument and controller can be coupled (e.g., communicatively, electronically, wirelessly, and / or mechanically) such that manipulation of the controller causes a corresponding manipulation of the instrument via, for example, master-slave control.

[0061] 14 is a perspective view of one embodiment of the controller 242. In the illustrated embodiment, the controller 242 is configured to enable operation of two medical instruments and includes two handles 244. Each of the handles 244 is connected to a gimbal 246. Each gimbal 246 is connected to a positioning platform 248.

[0062] 14, each positioning platform 248 includes a SCARA arm (selective compliance assembly robot arm) 258 coupled to a column 254 by a prismatic joint 256. The prismatic joint 256 is configured to translate along the column 254 (e.g., along a rail 257) to allow each of the handles 244 to translate in the z-direction, providing a first degree of freedom. The SCARA arm 258 is configured to allow movement of the handles 244 in the xy-plane, providing an additional two degrees of freedom.

[0063] F. Navigation and Control. Traditional endoscopy may involve the use of fluoroscopy (e.g., as may be delivered through a C-arm) and other forms of radiation-based imaging modalities to provide intraluminal guidance to the operator-physician. In contrast, the robotic system contemplated by the present disclosure may provide non-radiation-based navigation and localization means to reduce the physician's exposure to radiation and reduce the amount of equipment in the operating room. As used herein, the term "localization" may refer to determining and / or monitoring the position of an object in a reference coordinate system. Techniques such as pre-operative mapping, computer vision, real-time EM tracking, and robot command data may be used individually or in combination to achieve a radiation-free surgical environment. In other cases where radiation-based imaging modalities are still used, pre-operative mapping, computer vision, real-time EM tracking, and robot command data may be used individually or in combination to improve information available only through radiation-based imaging modalities.

[0064] As discussed above, the robotic systems discussed herein can be designed to incorporate one or a combination of two or more of the above-mentioned techniques. The computer-based control system of the tower, bed, and / or cart-based robotic system can store, for example, in a non-transitory computer-readable storage medium, such as a persistent magnetic storage drive, solid-state drive, etc., computer program instructions that, when executed, cause the system to receive and analyze sensor data and user commands, generate control signals throughout the system, and display navigational and localization data, such as instrument position within a global coordinate system, anatomical maps, etc.

[0065] 2. Protective grounding systems for medical devices. SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure relate to systems and methods for testing and / or monitoring protective earth connections in medical systems and devices.

[0066] Medical systems and devices, such as the systems described above, may include a protective earth system for grounding enclosures (of such systems and / or devices) to reduce the risk of electrical shock to patients and operators. In some embodiments, the protective earth system includes a protective earth conductor. In some embodiments, the earth line includes a return path for power and logic components of the medical system (or device). In some embodiments, the protective earth conductor connects the system enclosure to an earth line. In some embodiments, the protective earth conductor includes the system enclosure. In some embodiments, the protective earth system includes a test circuit coupled to the protective earth conductor and configured to measure the impedance through the protective earth conductor to the earth line. The measured impedance may be used to monitor or determine the continuity of the protective earth conductor.

[0067] Those skilled in the art will appreciate that the systems and devices described herein may also have application in non-medical situations, for example, the protective grounding systems described herein may be implemented in robotic systems and devices used in non-medical environments.

[0068] 15A-15C illustrate an exemplary protective grounding system, according to some embodiments. FIG. 15A shows a protective grounding system 400 including a test circuit 402 coupled to a protective earth (PE) wire 406 via an isolation capacitor 404. The protective earth wire 406 in FIG. 15A is connected to an enclosure 412 of the medical system and is connected (directly or indirectly) to a ground (GND) line 410. In some embodiments, the protective earth wire 406 is connected to the enclosure 412 via one or more mechanical fasteners (e.g., screws, nails, or staples). In some embodiments, the protective earth wire 406 is connected to a ground line 410 via one or more mechanical fasteners (e.g., screws, nails, or staples). FIG. 15A further shows a load 408, which represents the impedance of the PE-GND connection as measured by the test circuit 402.

[0069] FIG. 15B illustrates a protective earth system 416 similar to the protective earth system 400 of FIG. 15A, except that the protective earth wire 406 is connected to two earth lines 410-1 and 410-2 with corresponding loads 408 and 411. According to some embodiments, the protective earth system 416 represents a scenario in which the protective earth system 400 has an additional electrical connection to the GND line 410 (in addition to the first electrical connection to the GND line represented by the load 408). The additional electrical connection may represent an unintentional short between the PE wire 406 and the GND line 410. An unintentional short may be undesirable as it may introduce additional noise into the GND line 410 and / or reduce the shielding effect provided by the enclosure 412 to the internal components of the medical system. Because loads 408 and 411 in FIG. 15B are connected in parallel, the total impedance measured by test circuit 402 in protective earth system 416 is low compared to the total impedance measured by test circuit 402 in protective earth system 400 (e.g., load 408 alone).

[0070] 15C illustrates a protective earth system 418 that is similar to the protective earth system 400 of FIG. 15A, except that the load 408 in FIG. 15A is replaced by a load 413. According to some embodiments, the load 413 is larger than the load 408 (e.g., represents a larger impedance of the PE-GND connection measured by the test circuit 402). According to some embodiments, the protective earth system 418 represents a scenario in which the protective earth wire 406 has a higher impedance (compared to FIG. 15A) due to degradation of the PE wire 406 and / or the connection between the PE wire 406 and the GND line 410. The increased impedance may be undesirable as it may increase the likelihood of an electric shock received by a patient or an operator of the medical system.

[0071] FIG. 16 illustrates components of a test circuit 402 for a protective earth system, according to some embodiments. The test circuit 402 of FIG. 16 includes a signal generator 430 coupled (e.g., directly or indirectly connected) to an isolation capacitor 404 via a voltage-to-current converter (VCC) 432. In some embodiments, the signal generator 430 is also coupled (e.g., directly or indirectly connected) to a ground line 429. As shown in FIG. 16, the signal generator 430 is coupled (e.g., directly or indirectly connected) to a lock-in amplifier component 433. In some embodiments, the signal generator 430 is coupled (e.g., directly or indirectly connected) to the lock-in amplifier component 433 via a buffer 428. Also shown in FIG. 16, the isolation capacitor 404 is coupled (e.g., directly or indirectly connected) to the lock-in amplifier component 433. In some embodiments, the isolation capacitor 404 is coupled (e.g., directly or indirectly connected) to the lock-in amplifier component 433 via a buffer 426. According to some embodiments, the lock-in amplifier component 433 includes an analog mixer 424, a low-pass filter 422, and an analog-to-digital converter (ADC) 420. In this manner, no direct current (DC) path is formed between the test circuitry 402 and the PE line 406.

[0072] In some embodiments, the signal generator 430 operates at a carrier frequency (f c) in some embodiments. In some embodiments, the carrier frequency is in the range of 20 kilohertz to 500 kilohertz. In some embodiments, the carrier frequency is in the range of 500 kilohertz to 50 megahertz. In some circumstances, a higher frequency in the range corresponds to a faster circuit requirement to multiply, filter, and measure the response signal. In some circumstances, a lower frequency in the range corresponds to a slower circuit requirement to multiply, filter, and measure the response signal. In some embodiments, the isolation capacitor (e.g., isolation capacitor 404) is sized (e.g., has a capacitance value) to act as a high pass filter. In some embodiments, the isolation capacitor is selected to have a capacitance such that the corresponding RC cutoff frequency (e.g., the RC cutoff frequency of the test circuit) is on the order of the carrier frequency. In some embodiments, the isolation capacitor is selected to have a capacitance such that the corresponding RC cutoff frequency is lower than the carrier frequency (e.g., half the carrier frequency or an order of magnitude lower than the carrier frequency). In some embodiments, the signal generator 430 is configured to generate a square wave or a sinusoidal voltage waveform. In some situations, a square waveform may be easier to generate, but more difficult to lock onto (compared to a sine waveform) because it contains a range of frequencies.

[0073] In some embodiments, the voltage to current converter 432 is or includes a voltage controlled current source (VCCS). In some embodiments, the analog mixer 424 is an analog multiplier (e.g., an analog multiplying mixer). In some embodiments, the analog mixer 424 mixes the signal from the PE line 406 (e.g., received via the isolation capacitor 404 and the buffer 426) with a carrier frequency (f c) (e.g., received via buffer 428). In some embodiments, the signal from PE line 406 corresponds to (or is indicative of, or depends on) the impedance of load 408. In some embodiments, low pass filter 422 is configured to filter out alternating current (AC) frequencies (e.g., to isolate DC signals). In some embodiments, low pass filter 422 is configured to filter out all frequencies, including the carrier frequency, to isolate DC signals. In some embodiments, lock-in amplifier component 433 includes a digital lock-in amplifier 434 (e.g., using a discrete fast Fourier transform (DFFT)). For example, lock-in amplifier component 433 includes ADC 435 and digital signal processing (DSP) component 437 configured to perform lock-in amplification. In some embodiments, lock-in amplifier component 433 includes a digital lock-in amplifier 434 without (e.g., instead of) low pass filter 422 and analog mixer 424.

[0074] In some embodiments, the signal generator 430 is configured to output a waveform having a maximum voltage of less than 1 millivolt (e.g., 100 microvolts, 50 microvolts, or 20 microvolts). In some embodiments, the signal generator 430 is configured to output a waveform having a maximum voltage of at least 1 volt (e.g., 1.8 volts, 2.5 volts, 3.3 volts, or 5 volts). In some embodiments, the voltage to current converter 432 is configured to output a maximum peak current below a safety threshold (e.g., below 100 microamps, 50 microamps, or 20 microamps).

[0075] 17A illustrates a protective earth system 438 according to some embodiments. The protective earth system 438 is similar to the protective earth system 400, except that the protective earth system 438 includes a second test circuit 442 connected to the protective earth wire 406 via a second isolation capacitor 444. In some embodiments, the second test circuit 442 is similar to the test circuit 402 described herein. The protective earth system 438 can measure the load or impedance of the PE wire 406 when the load or impedance of the PE wire 406 is better represented as a distributed load or impedance (e.g., the load or impedance of the PE wire 406 is represented by a combination of load 408 and load 446, e.g., due to the length of the PE wire 406 or the involvement of one or more joints). In some embodiments, a comparison of the impedance measured by the test circuit 402 and the impedance measured by the second test circuit 442 identifies portions of the PE wire 406 that have a changed impedance.

[0076] 17B illustrates a protective earth system 448 according to some embodiments. The protective earth system 448 includes a test circuit 402 coupled to PE lines 406-1 and 406-2 via a switching component 450. According to some embodiments, the switching component 450 includes a switch 451-1 coupled to the PE line 406-1 and a switch 451-2 coupled to the PE line 406-2. The test circuit 402 is coupled to the PE line 406-1 via a switch 451-1 and an isolation capacitor 404-1. The PE line 406-1 is coupled to an enclosure 412-1 and a ground 410-1 and has a corresponding load 408-1. The test circuit 402 is coupled to the PE line 406-2 via a switch 451-2 and an isolation capacitor 404-2. The PE line 406-2 is coupled to an enclosure 412-2 and a ground 410-2 and has a corresponding load 408-2.

[0077] In some embodiments, the switch component 450 is configured to selectively couple the test circuit 402 to the PE lines 406-1 and 406-2 such that the impedance of each PE line can be measured. For example, at a first time, the switch 451-1 is closed and the switch 451-2 is open. This allows the test circuit 402 to measure the impedance of the load 408-1 at the first time. In this example, at a second time, the switch 451-1 is open and the switch 451-2 is closed. This allows the test circuit 402 to measure the impedance of the load 408-2 at the second time. In this manner, the test circuit 402 can monitor and test multiple PE lines 406. In some embodiments, the switch component 450 includes three or more switches (e.g., four or five or more switches, five or six or more switches, etc.) for independently testing three or more PE lines.

[0078] FIG. 18 illustrates a robot arm 500 having a protective ground system, according to some embodiments. In some embodiments, the robot arm 500 is an instance of any one of the aforementioned robot arms (e.g., robot arms 12, 39, 50, 142, 176, 182, or 258). The robot arm 500 includes a test circuit 502, joints 504 (e.g., 504-1 through 504-4), an arm support 510, and a protective ground connection 512 that leads to earth. Each of the joints 504 includes one or more degrees of freedom (DoF). In some embodiments, the joint 504-1 is a base joint (A0 joint) located at or near the base of the robot arm 500. In some embodiments, the joint 504-1 is a prismatic joint that allows the robot arm 500 to translate (e.g., along the y-axis) along a support 510 (e.g., a fixed frame or an adjustable arm support). In some embodiments, the joint 504-2 rotates relative to the base joint 504-1. In some embodiments, the joint 504-3 includes multiple DoFs to facilitate both tilting and rotating the robot arm relative to the joint 504-3. In some embodiments, the joint 504-4 includes an elbow joint. According to some embodiments, the robot arm 500 includes a protective ground wire (e.g., one or more conductive enclosures of the robot arm around multiple links) that connects the test circuit 502 to a PE connection 512 that leads to earth. In some embodiments, the PE wire passes through the joint 504 (e.g., the joint 504 may include a conductive component to provide connectivity to the PE wire). Thus, the PE wire may be subject to degradation over time due to movement of the joint 504.

[0079] In some embodiments, test circuit 502 is an instance of test circuit 402. According to some embodiments, test circuit 402 is configured to measure the impedance of the PE line and PE connection 512 to ground. Thus, test circuit 402 is configured to measure any additional impedance introduced through degradation of the PE line at one or more of the joints 504.

[0080] 19 is a flow chart illustrating a method 600 for testing a protective ground conductor of a robotic system, according to some embodiments. The method 600 is implemented in a robotic system (e.g., medical system 36) having one or more processors (e.g., processor 280) and a memory (e.g., memory 282). In some embodiments, the memory (e.g., memory 282) stores instructions for execution by the one or more processors (e.g., processor 280). In some embodiments, the robotic system includes a robotic arm. In some embodiments, a first robotic arm is connected to a medical instrument.

[0081] The robotic system applies (602) a test signal to a protective ground conductor (e.g., protective ground conductor 406) through an isolation capacitor (e.g., capacitor 404) electrically coupled to the protective ground conductor. For example, test circuit 402 can apply the test signal to protective ground conductor 406 through isolation capacitor 404. In some embodiments, the test signal is a sinusoidal or square waveform having a particular frequency (e.g., carrier frequency). In some embodiments, the test signal is a test current (e.g., the test signal is a current input). In some embodiments, the test signal has a maximum current that is below a safety threshold of the robotic system (e.g., less than 50 microamps).

[0082] The robotic system obtains 604 a response signal from the protective ground conductor via an isolation capacitor (e.g., capacitor 404). In some embodiments, the robotic system receives a voltage signal corresponding to the test current applied through an impedance load (e.g., load 408) corresponding to the protective ground conductor. In some embodiments, the response signal is a voltage signal having a maximum voltage of less than 100 microvolts (e.g., less than 50 microvolts).

[0083] The robotic system measures (606) the impedance for the protective ground wire based on the acquired signal using a lock-in amplifier (e.g., lock-in amplifier component 433). For example, the robotic system generates a test signal having a carrier frequency, and the robotic system uses the lock-in amplifier to isolate and amplify the carrier frequency in a signal received from the protective ground wire in response to the test signal. In some embodiments, the robotic system measures phase data of the acquired signal and correlates the phase data with the capacitive and inductive components of the impedance. In some embodiments, the robotic system uses the capacitive and inductive components of the impedance to determine the validity of the protective ground connection to earth.

[0084] In some embodiments, the robotic system (i) generates 608 a waveform having a carrier frequency via a signal generator (e.g., signal generator 430); (ii) combines the waveform from the signal generator with a signal through an isolation capacitor via an analog multiplying mixer (e.g., analog mixer 424); and (iii) filters the output of the analog mixer via a low pass filter (e.g., low pass filter 422). For example, the robotic system uses analog mixer 424 (e.g., analog multiplier) to multiply the carrier frequency from the signal generator 430 with the current-induced voltage in the isolation capacitor 404. In this example, the output of the analog mixer is filtered through low pass filter 422 to isolate the DC signal and passed to ADC 420 for measurement. In some embodiments, the output of the low pass filter is a direct current (DC) signal. In some cases, the DC signal is proportional to the impedance of the connection to the protective earth wire and earth (e.g., load 408).

[0085] In some embodiments, the robotic system measures 610 the impedance through one or more joints of the robotic system (e.g., joint 504). In some embodiments, the one or more joints are configured to allow free infinite rotation. Thus, in some embodiments, the PE wire is passed through the one or more joints via a slip ring and brush interface.

[0086] In some embodiments, the robotic system measures 612 the impedance through the isolation capacitor to a ground line electrically coupled to the protective ground conductor (e.g., ground line 410). In some embodiments, measuring the impedance to the protective ground conductor includes determining the impedance between the protective ground conductor and earth.

[0087] The robotic system compares (614) the measured impedance to a baseline impedance. In some embodiments, the baseline impedance is 10 ohms or less (e.g., 10 ohms, 5 ohms, 2 ohms, or 1 ohm). In some embodiments, the baseline impedance is the impedance due to expected parasitics of the robotic system (e.g., wire series resistance, connectors, copper traces, etc.). For example, in some cases, the baseline impedance corresponds to the impedance of a protective ground conductor measured during production (e.g., prior to sale or deployment of the robotic system). In some embodiments, the baseline impedance is measured during production or prior to sale or deployment of the robotic system. In some embodiments, the baseline impedance is measured during a maintenance operation (e.g., during routine maintenance).

[0088] In some embodiments, the robotic system identifies 616 an unintended short between the protective ground wire and the earth line (e.g., an additional unintended short due to a fault) in response to the measured impedance falling below the baseline impedance. In some embodiments, the robotic system identifies a discontinuity between the protective ground wire and the earth line in response to the measured impedance rising above the baseline impedance.

[0089] The robotic system provides information indicative of the results of the comparison (618). For example, the robotic system provides the information to an operator of the robotic system. In some embodiments, the robotic system provides the information on a display of the robotic system (e.g., touch screen 26). In some embodiments, the robotic system provides the information to a device communicatively coupled to the robotic system (e.g., a computer system or an alarm on the same network as the robotic system). In some embodiments, providing the information includes initiating an alert or warning that the robotic system is unsafe to use (e.g., due to a discontinuity in the PE line). In some configurations, the alert or warning includes a visual alert or warning (e.g., a warning indicator). In some configurations, the alert or warning includes an audible alert or warning (e.g., a warning sound).

[0090] In some embodiments, the robotic system presents information regarding the identified shorts and identified discontinuities to an operator of the robotic system (620). In some embodiments, the robotic system presents the measured impedance values ​​and information regarding whether the measured impedance values ​​are above or below expected impedance values. In some embodiments, the measured impedance values ​​and information regarding whether the measured impedance values ​​are above or below expected impedance values ​​are presented on a display device (e.g., a monitor or screen of the console 31).

[0091] In some embodiments, the robotic system includes (i) an earth line (e.g., earth line 410); (ii) a protective ground conductor (e.g., protective ground conductor 406) electrically coupled to the earth line at a first point; and (iii) a test circuit (e.g., test circuit 402) coupled to the protective ground conductor at a second point via an isolation capacitor (e.g., isolation capacitor 404).

[0092] In some embodiments, the test circuit includes a lock-in amplifier (e.g., lock-in amplifier component 433) and is configured to measure an impedance for the protective ground conductor. In some embodiments, the protective ground conductor is shorted to a ground line at a first point. In some embodiments, the test circuit is not directly coupled to the protective ground conductor (e.g., coupled only through an isolation capacitor). In some embodiments, a capacitor coupled to the protective ground conductor forms a high pass filter. In some embodiments, the capacitor is sized according to the carrier frequency of the test circuit. In some embodiments, the impedance of the protective ground conductor includes the impedance of the isolation capacitor, the impedance of the protective ground conductor, and the impedance of the electrical coupling between the protective ground conductor and the ground line.

[0093] In some embodiments, the lock-in amplifier includes (i) a signal generator (e.g., signal generator 430) coupled to an isolation capacitor and configured to generate a waveform having a carrier frequency, (ii) an analog mixer (e.g., analog mixer 424) for combining the waveform from the signal generator with a signal through the isolation capacitor, and (iii) a low pass filter (e.g., low pass filter 422) coupled to an output of the analog mixer.

[0094] In some embodiments, the low pass filter is configured to isolate DC signals (e.g., filter out all AC frequencies). In some embodiments, an ADC (e.g., ADC 420) is coupled to the output of the low pass filter. In some embodiments, the signal generator is configured to generate a sine wave signal or a square wave signal. In some embodiments, the signal generator includes a voltage waveform generator coupled to a voltage to current converter (VCC) or a voltage controlled current source (VCCS). In some embodiments, the analog mixer is or includes an analog multiplier.

[0095] In some embodiments, the signal generator is configured to output a signal having a maximum peak current that is below a safety threshold (eg, a safety threshold of 50 microamps).

[0096] In some embodiments, the lock-in amplifier includes digital signal processing (DSP) circuitry (e.g., DSP circuitry 437 of the digital lock-in amplifier 434). For example, the lock-in amplifier includes an ADC 435 and a DSP circuitry 437 coupled to an output of the ADC. In some embodiments, the DSP circuitry 437 is configured to perform the lock-in amplification via a DFFT operation.

[0097] In some embodiments, the second point is distant from the first point, and the test circuit is configured to measure the impedance between the first point and the second point. For example, a protective ground wire is connected to an earth line at the base of the robotic system, and the test circuit is coupled to the protective ground wire at the top of the robotic system. In this example, the test circuit is configured to measure the impedance from the top of the robotic system to the base of the robotic system. As another example, FIG. 18 shows a test circuit 502 at one end of a robotic arm 500 (e.g., at the distal end of the robotic arm) and a PE connection 512 to earth at the opposite end of the robotic arm 500 (e.g., at the proximal end of the robotic arm).

[0098] In some embodiments, the robotic system includes one or more joints, and measuring the impedance between the first point and the second point includes measuring the impedance through the one or more joints. For example, test circuit 502 of FIG. 18 measures the impedance through joint 504 as part of measuring the impedance of the PE line to ground.

[0099] In some embodiments, (i) the test circuit is a first test circuit, (ii) the robotic system further includes a second test circuit coupled to the protective ground line at a third point, and (iii) the second test circuit is configured to measure an impedance between the first point and the third point (e.g., FIG. 17A). For example, the first test circuit is located in a first robot arm of the robotic system, and the second test circuit is located in a second robot arm of the robotic system. In this example, each test circuit measures an impedance with respect to the protective ground line of the corresponding robot arm. In some embodiments, the first test circuit uses a first carrier frequency and the second test circuit uses a second carrier frequency that is different from the first carrier frequency (e.g., 1%, 5%, or 10% different). In some embodiments, the first test circuit and the second test circuit use the same carrier frequency.

[0100] In some embodiments, (i) the robotic system further includes a second protective ground conductor (e.g., protective ground conductor 406-2) electrically coupled to a ground conductor (e.g., ground 410-2) at a third point, and (ii) the test circuit is configured to (a) measure a first impedance between the second point and the first point, and (b) measure a second impedance between the second point and a third point. For example, protective ground system 448 in FIG. 17B shows test circuit 402 electrically coupled to protective ground conductors 406-1 and 406-2 and configured to measure impedance for the protective ground conductor.

[0101] In some embodiments, (i) the isolation capacitor is a first isolation capacitor, (ii) the test circuit is coupled to a second protective ground conductor (e.g., protective ground conductor 406-2) via a second isolation capacitor (e.g., isolation capacitor 404-2), and (iii) the test circuit further includes a switching component (e.g., switching component 450) for selectively coupling the lock-in amplifier to the first isolation capacitor or the second isolation capacitor.

[0102] In some embodiments, the robotic system further includes a controller (e.g., processor 280) coupled to the test circuit, the controller configured to: (i) compare the impedance for the protective ground conductor to a baseline impedance value; (ii) identify an (unintentional) short between the protective ground conductor and the earth line in response to the impedance for the protective ground conductor falling below the baseline impedance value; and (iii) identify a discontinuity between the protective ground conductor and the earth line in response to the impedance for the protective ground conductor rising above the baseline impedance value. In some embodiments, the controller includes a hardware comparator circuit. In some embodiments, the identification of a discontinuity causes the robotic system to automatically enter an emergency stop state.

[0103] In some embodiments, the robotic system further includes a user interface (e.g., console 31) configured to present information regarding the identified shorts and the identified discontinuities to an operator of the robotic system. For example, the user interface may include a display panel, warning lights, and / or a speaker that issues an audible warning.

[0104] In some embodiments, the robotic system is configured to periodically test the protective ground conductor using the test circuitry (e.g., weekly, daily, hourly, etc.). In some embodiments, the robotic system is configured to test the protective ground conductor using the test circuitry as part of the startup (power-on) sequence of the robotic system. In some embodiments, the robotic system is configured to test the protective ground conductor prior to use in a medical procedure. In some embodiments, the robotic system is configured to test the protective ground conductor prior to a procedure requiring high voltage operation (e.g., electrocautery). In some embodiments, the robotic system is configured to continuously test the protective ground conductor using the test circuitry.

[0105] In some embodiments, the robotic system further includes a metal enclosure (e.g., enclosure 412), and the protective ground conductor is electrically coupled to the metal enclosure. In some embodiments, the robotic system includes a housing, and the test circuitry is disposed within the housing. In some embodiments, the housing is enclosure 412. In some embodiments, the robotic system includes a conductive enclosure. In some embodiments, the protective ground conductor is integral with the metal enclosure. In some embodiments, the metal enclosure constitutes the protective ground conductor.

[0106] In some embodiments, the robotic system includes (i) a ground line, (ii) a protective ground conductor, and (iii) a test circuit coupled to the protective ground conductor through an isolation capacitor electrically coupled to the protective ground conductor. In some embodiments, the test circuit is configured to measure an impedance through the isolation capacitor, through the protective ground conductor, to the ground line. In some embodiments, the test circuit includes a lock-in amplifier.

[0107] 3. Implementation Systems and Terminology. FIG. 20 is a schematic diagram illustrating electronic components of a system (e.g., a medical and / or robotic system). The system includes one or more processors 280 in communication with a computer-readable storage medium of memory 282 (e.g., computer memory devices such as random access memory, read-only memory, static random access memory, and non-volatile memory, as well as other storage devices such as hard drives, optical disks, magnetic tape recordings, or any combination thereof) that stores instructions for performing any of the methods described herein (e.g., the operations described with respect to FIG. 19). The one or more processors 280 communicate with test circuitry 294 and a user interface 298. In some embodiments, the user interface 298 includes one or more human-machine interface (HMI) components, such as a console (e.g., console 31), a display (e.g., touch screen 26), a speaker, and / or a warning light (e.g., LED). In some embodiments, the test circuitry 294 is an instance of test circuitry 402. The test circuit 294 communicates with (or is electrically coupled to) the protective ground conductor 296. In some embodiments, the protective ground conductor 296 is an instance of the protective ground conductor 406. In some embodiments, the protective ground conductor 296 is integrated with or coupled to the enclosure of the system (e.g., a metal housing for the system). The test circuit 294 is configured to test the protective ground conductor 296 (e.g., transmit a test signal to the protective ground conductor 296 and receive a response signal from the protective ground conductor 296). In some embodiments, the test circuit 294 is configured to transmit the results of the test to the processor 280. In some embodiments, the test circuit 294 is configured to transmit data obtained for the test (e.g., intermediate data) to the processor 280 for further processing and analysis. For example, the test circuit 294 measures an impedance for the protective ground conductor 296 and transmits the measured impedance to the processor 280 for comparison to a baseline impedance (e.g., a baseline impedance stored in the memory 282).In some embodiments, the one or more processors 280 are configured to analyze test data from the test circuitry 294 and generate test information that is provided to a user of the system (e.g., provided via a user interface 298).

[0108] The one or more processors 280 also communicate (via a system bus or any suitable electrical circuitry) with an input / output controller 284. The input / output controller 284 receives user input from an input device 286 (e.g., the robotic arm 182, or the instrument 200), and optionally receives sensor data from one or more sensors, and relays the data and user input to the one or more processors 280. The input / output controller 284 also receives instructions and / or data from the one or more processors 280, and relays the instructions and / or data to one or more actuators (actuators and motors for driving the robotic arms of the system), such as motors 292-1 and 292-2. In some embodiments, the input / output controller 284 is coupled to one or more actuator controllers 290 and provides instructions and / or data to at least a subset of the one or more actuator controllers 290, which in turn provide control signals to selected actuators 292. In some embodiments, one or more actuator controllers 290 are integrated with the input / output controller 284, which provides control signals directly to one or more actuators 292 (without a separate actuator controller).

[0109] It should be noted that, as used herein, the terms "couple," "coupled," "coupled," or other variations of the word coupled, may indicate either an indirect connection or a direct connection. For example, when a first component is "coupled" to a second component, the first component may be either indirectly connected to the second component through another component, or directly connected to the second component.

[0110] The term "computer-readable medium" refers to any available medium that can be accessed by a computer or processor. By way of example, and not limitation, such media may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory, compact disc read-only memory (CD-ROM), or other optical disk storage, magnetic disk storage, or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. It should be noted that computer-readable media may be tangible and non-transitory. As used herein, the term "code" may refer to software, instructions, code, or data that is executable by a computing device or processor.

[0111] The methods disclosed herein include one or more steps or actions for achieving the described method. The method steps and / or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is required for the proper operation of the described method, the order and / or use of specific steps and / or actions may be modified without departing from the scope of the claims.

[0112] As used herein, the term "plurality" refers to two or more. For example, a plurality of components refers to two or more components. The term "determining" encompasses a wide variety of acts, and thus "determining" can include calculating, computing, processing, deriving, investigating, looking up (e.g., consulting a table, database, or another data structure), ascertaining, and the like. Also, "determining" can include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. Also, "determining" can include resolving, selecting, electing, establishing, and the like.

[0113] The phrase "based on" does not mean "based only on," unless expressly specified otherwise. In other words, the phrase "based on" refers to both "based only on" and "based at least on."

[0114] The foregoing description of the disclosed implementations is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these implementations will be readily apparent to those skilled in the art, and the general principles set forth herein may be applied to other implementations without departing from the scope of the present invention. For example, those skilled in the art will recognize that many corresponding alternatives, equivalent structural details, such as similar manners of fastening, mounting, coupling, or engaging tool components, equivalent mechanisms for producing specific actuation motions, and equivalent mechanisms for delivering electrical energy, may be employed. Thus, the present invention is not intended to be limited to the implementations shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0115] 4. Examples of subject technology clauses. The following clauses describe several embodiments or implementations.

[0116] Clause 1. A robotic system comprising: Earth line, a protective earth conductor electrically coupled to the earth line at a first point; and a test circuit coupled to the protective ground conductor at a second point via an isolation capacitor, the test circuit comprising a lock-in amplifier and configured to measure an impedance for the protective ground conductor.

[0117] Clause 2. The lock-in amplifier a signal generator coupled to the isolation capacitor and configured to generate a waveform having a carrier frequency; an analog mixer for combining the waveform from the signal generator with the signal from the isolation capacitor; and a low pass filter coupled to an output of the analog mixer.

[0118] Clause 3. The robotic system of clause 2, wherein the signal generator is configured to output a signal having a maximum peak current below a safety threshold.

[0119] Clause 4. A robot system according to any one of clauses 1 to 3, wherein the lock-in amplifier comprises digital signal processing (DSP) circuitry.

[0120] Clause 5. A robot system described in any of clauses 1 to 4, wherein the second point is spaced from the first point, and the test circuit is configured to measure impedance between the first point and the second point.

[0121] Clause 6. The robotic system of clause 5, wherein the robotic system comprises one or more joints, and measuring the impedance between the first point and the second point comprises measuring the impedance through the one or more joints.

[0122] Article 7. the test circuit is a first test circuit; the robotic system further comprising a second test circuit coupled to the protective ground at a third point; 7. The robot system of claim 5 or 6, wherein the second test circuit is configured to measure impedance between the first point and a third point.

[0123] Article 8. a second protective earth conductor electrically coupled to the earth line at a third point; The test circuit is Measuring a first impedance between the second point and the first point; and measuring a second impedance between the second point and a third point.

[0124] Article 9. the isolation capacitor is a first isolation capacitor; a test circuit coupled to the second protective earth conductor through a second isolation capacitor; 9. The robotic system of claim 8, wherein the test circuit further comprises a switching component for selectively coupling the lock-in amplifier to the first isolation capacitor or the second isolation capacitor.

[0125] Clause 10. The method further comprising: comparing the impedance to a baseline impedance value for the protective earth conductor; identifying a short circuit between the protective earth conductor and the earth line in response to the impedance for the protective earth conductor falling below a baseline impedance value; and identifying a discontinuity between the protective earth line and the earth line in response to the impedance of the protective earth line exceeding a baseline impedance value.

[0126] Clause 11. The robotic system of clause 10, further comprising a user interface configured to present information regarding the identified shorts and the identified discontinuities to an operator of the robotic system.

[0127] Clause 12. A robot system described in any one of clauses 1 to 11, wherein the robot system is configured to periodically test the protective earth conductor using a test circuit.

[0128] Clause 13. A robot system as described in any of clauses 1 to 12, wherein the robot system is configured to test the protective earth conductor using the test circuit as part of a start-up sequence for the robot system.

[0129] Clause 14. A robot system described in any one of clauses 1 to 13, further comprising a metal enclosure, the protective ground wire being electrically coupled to the metal enclosure.

[0130] Clause 15. A method for testing a protective earth conductor of a robotic system, the method comprising: applying a test signal to the protective earth conductor through an isolation capacitor electrically connected to the protective earth conductor; obtaining a signal from the protective earth conductor via an isolation capacitor in response to the test signal; measuring an impedance for the protective earth conductor based on the acquired signal, the measuring being performed by a lock-in amplifier; Comparing the measured impedance to a baseline impedance; and providing information indicative of a result of the comparison.

[0131] Article 16. Measuring generating a waveform having a carrier frequency via a signal generator; combining a waveform from a signal generator through an analog mixer with a signal passing through an isolation capacitor; 16. The method of claim 15, comprising filtering the output of the analog mixer through a low pass filter.

[0132] Clause 17. The method of clause 15 or clause 16, wherein measuring the impedance to the protective earth conductor comprises measuring the impedance through one or more joints of the robotic system.

[0133] Clause 18. The method of any of clauses 15-17, wherein measuring the impedance across the protective earth conductor includes measuring the impedance through an isolation capacitor to a ground line electrically coupled to the protective earth conductor.

[0134] Article 19. Comparison identifying a short circuit between the protective earth conductor and the earth conductor in response to the measured impedance being below a baseline impedance; and identifying a discontinuity between the protective earth conductor and the earth conductor in response to the measured impedance exceeding the baseline impedance.

[0135] Clause 20. The method of clause 19, wherein providing information indicative of a result of the comparison includes presenting information regarding the identified shorts and the identified discontinuities to an operator of the robotic system.

[0136] Clause 21. A method according to any one of clauses 15 to 20, wherein the method is performed as part of a start-up sequence of a robotic system.

[0137] Clause 22. A robot system comprising: Earth line, A protective earth wire; a test circuit coupled to the protective ground conductor via an isolation capacitor electrically coupled to the protective ground conductor and configured to measure impedance through the isolation capacitor, through the protective ground conductor, to an earth line.

[0138] Clause 23. The robot system of clause 22, wherein the test circuitry includes a lock-in amplifier.

[0139] Clause 24. A method for testing a protective earth conductor of a robotic system, the method comprising: providing a test current to the protective earth conductor through an isolation capacitor electrically coupled to the protective earth conductor; obtaining a voltage signal across the isolation capacitor in response to the test current; determining an impedance for the protective earth conductor based on the acquired voltage signal; and providing information indicative of continuity of the protective earth conductor based on the determined impedance.

[0140] Clause 25. The method of clause 24, wherein the test current is provided at a carrier frequency, the method further comprising amplifying a component of the voltage signal having the carrier frequency with a lock-in amplifier.

[0141] [Embodiment] (1) A robot system comprising: Earth line, a protective earth conductor electrically coupled to the earth line at a first point; a test circuit coupled to the protective ground conductor at a second point via an isolation capacitor, the test circuit comprising a lock-in amplifier and configured to measure an impedance for the protective ground conductor. (2) The lock-in amplifier a signal generator coupled to the isolation capacitor and configured to generate a waveform having a carrier frequency; an analog mixer for combining the waveform from the signal generator with the signal from the isolation capacitor; A robot system as described in embodiment 1, comprising a low pass filter coupled to an output of the analog mixer. (3) The robot system of embodiment 2, wherein the signal generator is configured to output a signal having a maximum peak current below a safety threshold. (4) The robot system of embodiment 1, wherein the lock-in amplifier comprises digital signal processing (DSP) circuitry. (5) The robot system of embodiment 1, wherein the second point is distant from the first point, and the test circuit is configured to measure impedance between the first point and the second point.

[0142] (6) The robot system of embodiment 5, wherein the robot system includes one or more joints, and measuring the impedance between the first point and the second point includes measuring impedance through the one or more joints. (7) The test circuit is a first test circuit, the robotic system further comprising a second test circuit coupled to the protective ground conductor at a third point; 6. The robot system of embodiment 5, wherein the second test circuit is configured to measure impedance between the first point and the third point. (8) further comprising a second protective earth wire electrically coupled to the earth line at a third point; The test circuit comprises: Measuring a first impedance between the second point and the first point; 2. The robot system of embodiment 1, configured to measure a second impedance between the second point and the third point. (9) The insulating capacitor is a first insulating capacitor, the test circuit is coupled to the second protective ground line through a second isolation capacitor; 9. The robot system of claim 8, wherein the test circuit further comprises a switching component for selectively coupling the lock-in amplifier to the first isolation capacitor or the second isolation capacitor. (10) A controller coupled to the test circuit, the controller comprising: comparing the impedance of the protective earth conductor to a baseline impedance value; identifying a short between the protective earth conductor and the earth line in response to the impedance of the protective earth conductor falling below the baseline impedance value; and identifying a discontinuity between the protective ground line and the earth line in response to the impedance of the protective ground line exceeding the baseline impedance value.

[0143] (11) The robot system of embodiment 10, further comprising a user interface configured to present information regarding the identified short circuits and the identified discontinuities to an operator of the robot system. (12) The robotic system of embodiment 1, wherein the robotic system is configured to periodically test the protective ground conductor using the test circuit. (13) The robotic system of embodiment 1, wherein the robotic system is configured to test the protective ground conductor using the test circuit as part of a startup sequence of the robotic system. (14) The robot system of embodiment 1, further comprising a metal enclosure, the protective ground conductor being electrically coupled to the metal enclosure. (15) A method for testing a protective ground conductor of a robotic system, the method comprising: applying a test signal to the protective ground conductor through an isolation capacitor electrically coupled to the protective ground conductor; obtaining a signal from the protective earth conductor via the isolation capacitor in response to the test signal; measuring an impedance for the protective earth conductor based on the acquired signal, the measuring being performed by a lock-in amplifier; comparing the measured impedance to a baseline impedance; and providing information indicative of a result of said comparing.

[0144] (16) The measuring step generating a waveform having a carrier frequency via a signal generator; combining the waveform from the signal generator through an analog mixer with a signal across the isolation capacitor; 16. The method of claim 15, further comprising filtering the output of the analog mixer through a low pass filter. (17) The method of embodiment 15, wherein measuring the impedance of the protective ground conductor includes measuring the impedance through one or more joints of the robotic system. (18) The method of claim 15, wherein measuring the impedance of the protective earth conductor includes measuring the impedance through the isolation capacitor to a ground line electrically coupled to the protective earth conductor. (19) The comparing step identifying a short circuit between the protective earth conductor and the earth line in response to the measured impedance falling below the baseline impedance; and identifying a discontinuity between the protective earth conductor and the earth line in response to the measured impedance exceeding the baseline impedance. (20) The method of claim 19, wherein providing the information indicative of the results of the comparison includes presenting information regarding identified shorts and identified discontinuities to an operator of the robotic system.

[0145] (21) The method of embodiment 15, wherein the method is performed as part of a startup sequence of the robotic system. (22) A robot system comprising: Earth line, A protective earth wire; a test circuit coupled to the protective ground conductor via an isolation capacitor electrically coupled to the protective ground conductor and configured to measure an impedance through the isolation capacitor, through the protective ground conductor, to the earth line. (23) The robot system of claim 22, wherein the test circuit includes a lock-in amplifier. (24) A method for testing a protective ground conductor of a robotic system, the method comprising: providing a test current to the protective ground conductor through an isolation capacitor electrically coupled to the protective ground conductor; obtaining a voltage signal across the isolation capacitor in response to the test current; determining an impedance for the protective earth conductor based on the acquired voltage signal; and providing information indicative of continuity of the protective earth conductor based on the determined impedance. 25. The method of claim 24, wherein the test current is provided at a carrier frequency, the method further comprising amplifying a component of the voltage signal having the carrier frequency with a lock-in amplifier.

Claims

1. 1. A robot system comprising: Earth line, a protective ground conductor electrically coupled to the ground line at a first point; a test circuit coupled to the protective ground conductor at a second point via an isolation capacitor, the test circuit comprising a lock-in amplifier and configured to measure an impedance for the protective ground conductor.

2. The lock-in amplifier comprises: a signal generator coupled to the isolation capacitor and configured to generate a waveform having a carrier frequency; an analog mixer for combining the waveform from the signal generator with the signal from the isolation capacitor; a low pass filter coupled to an output of the analog mixer.

3. The robotic system of claim 2 , wherein the signal generator is configured to output a signal having a maximum peak current that is below a safety threshold.

4. The robotic system of claim 1 , wherein the lock-in amplifier comprises digital signal processing (DSP) circuitry.

5. The robotic system of claim 1 , wherein the second point is spaced from the first point, and the test circuit is configured to measure an impedance between the first point and the second point.

6. 6. The robotic system of claim 5, wherein the robotic system comprises one or more joints, and wherein measuring the impedance between the first point and the second point comprises measuring impedance through the one or more joints.

7. the test circuit is a first test circuit, the robotic system further comprising a second test circuit coupled to the protective ground line at a third point; The robotic system of claim 5 , wherein the second test circuit is configured to measure an impedance between the first point and the third point.

8. a second protective ground conductor electrically coupled to the ground line at a third point; The test circuit comprises: Measuring a first impedance between the second point and the first point; and measuring a second impedance between the second point and the third point.

9. the isolation capacitor is a first isolation capacitor; the test circuit is coupled to the second protective ground line through a second isolation capacitor; The robotic system of claim 8 , wherein the test circuitry further comprises a switching component for selectively coupling the lock-in amplifier to the first isolation capacitor or the second isolation capacitor.

10. A controller coupled to the test circuit, the controller comprising: comparing the impedance of the protective earth conductor to a baseline impedance value; identifying a short between the protective earth conductor and the earth line in response to the impedance of the protective earth conductor falling below the baseline impedance value; and identifying a discontinuity between the protective ground conductor and the earth line in response to the impedance for the protective ground conductor exceeding the baseline impedance value.

11. The robotic system of claim 10 , further comprising a user interface configured to present information regarding identified shorts and identified discontinuities to an operator of the robotic system.

12. The robotic system of claim 1 , wherein the robotic system is configured to periodically test the protective ground conductor using the test circuitry.

13. The robotic system of claim 1 , wherein the robotic system is configured to test the protective ground conductor using the test circuit as part of a startup sequence of the robotic system.

14. The robotic system of claim 1 , further comprising a metal enclosure, the protective ground conductor being electrically coupled to the metal enclosure.

15. 1. A method for testing a protective ground conductor of a robotic system, the method comprising: applying a test signal to the protective ground conductor through an isolation capacitor electrically coupled to the protective ground conductor; obtaining a signal from the protective earth conductor via the isolation capacitor in response to the test signal; measuring an impedance for the protective earth conductor based on the acquired signal, the measuring being performed by a lock-in amplifier; comparing the measured impedance to a baseline impedance; and providing information indicative of a result of said comparing.

16. The measuring step comprises: generating a waveform having a carrier frequency via a signal generator; combining the waveform from the signal generator through an analog mixer with a signal across the isolation capacitor; and filtering the output of the analog mixer through a low pass filter.

17. The method of claim 15 , wherein measuring the impedance to the protective ground conductor comprises measuring an impedance through one or more joints of the robotic system.

18. 16. The method of claim 15, wherein measuring the impedance to the protective ground conductor comprises measuring the impedance through the isolation capacitor to a ground line electrically coupled to the protective ground conductor.

19. The comparing step comprises: identifying a short circuit between the protective earth conductor and the earth line in response to the measured impedance falling below the baseline impedance; and identifying a discontinuity between the protective earth conductor and the earth conductor in response to the measured impedance exceeding the baseline impedance.

20. 20. The method of claim 19, wherein providing the information indicative of the results of the comparison comprises presenting information regarding identified shorts and identified discontinuities to an operator of the robotic system.

21. The method of claim 15 , wherein the method is performed as part of a start-up sequence of the robotic system.

22. 1. A robot system comprising: Earth line, A protective earth wire; a test circuit coupled to the protective ground conductor via an isolation capacitor electrically coupled to the protective ground conductor and configured to measure an impedance through the isolation capacitor, through the protective ground conductor, to the earth line.

23. 23. The robotic system of claim 22, wherein the test circuitry includes a lock-in amplifier.

24. 1. A method for testing a protective ground conductor of a robotic system, the method comprising: providing a test current to the protective ground conductor through an isolation capacitor electrically coupled to the protective ground conductor; obtaining a voltage signal across the isolation capacitor in response to the test current; determining an impedance for the protective earth conductor based on the acquired voltage signal; and providing information indicative of continuity of the protective earth conductor based on the determined impedance.

25. 25. The method of claim 24, wherein the test current is provided at a carrier frequency, the method further comprising amplifying a component of the voltage signal having the carrier frequency with a lock-in amplifier.

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