Torque sensing for robotic surgical systems

Abstract

A method of validating torque measurements of a reaction torque sensor of an instrument drive unit includes a controller that receives a validation signal, generates an acceptable torque range, receives a torque signal, compares the torque signal to the acceptable torque range, and stops the motor if the torque applied by the motor is outside the acceptable torque range. The validation signal indicates a current drawn by the motor, and the torque signal indicates a torque applied by the motor.

Description

[0001] This application is a divisional application of the Chinese invention patent application with application number 201680034888.8 (international application number PCT / US2016 / 037478), application date June 15, 2016, and invention name “Torque sensing for robotic surgical system”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 62 / 180,124, filed June 16, 2015, the entire disclosure of which is incorporated herein by reference. Background Art

[0004] Robotic surgical systems have been used in minimally invasive medical procedures. During such medical procedures, the robotic surgical system is controlled by a surgeon who interacts with a user interface. The user interface allows the surgeon to manipulate an end effector that acts on the patient. The user interface has input controls or handles that can be moved by the surgeon to control the robotic surgical system.

[0005] The end effectors of a robotic surgical system are positioned at the end of a surgical instrument connected to a robotic arm. Each end effector can be manipulated by an instrument drive unit (IDU). The IDU can have a drive motor associated with the end effector and configured to move the end effector about a corresponding axis or actuate a specific function of the end effector (e.g., approximation, pivoting, etc. of the jaws of the end effector).

[0006] Safety systems in robotic surgical systems monitor the drive motor current. If the measured motor current exceeds a preset safety threshold, a fault is inferred and the motor is shut down. These systems have limited ability to detect different types of faults because they do not take into account the actual force output by the motor.

[0007] There is a need for robust instrument drive unit fault detection that can identify different types of faults other than those related to pure high current consumption. Summary of the invention

[0008] In one aspect of the invention, verifying a torque measurement of a torque sensor of an instrument drive unit may include receiving a verification signal indicating a current drawn by a motor of the instrument drive unit. An acceptable torque range may be identified based on the verification signal. The torque measurement may be compared to the acceptable torque range. If the torque measurement is outside the acceptable torque range, the motor may be stopped.

[0009] In some aspects, the method may include measuring the torque applied by the motor using a reaction torque sensor electrically isolated from the motor. The reaction torque sensor may transmit a torque signal to the controller. The method may also include generating a fault signal when the torque applied by the motor is outside an acceptable torque range. Generating the fault signal may include providing feedback to the clinician in the form of audible, visual, or tactile feedback to the clinician.

[0010] In some aspects, the sensor can transmit a verification signal to the controller.The sensor can measure the current drawn by the motor to generate the verification signal.

[0011] In another aspect of the invention, a control circuit for a motor of an instrument drive unit includes a sensor, a reaction torque sensor, and a controller. The sensor is configured to detect a current drawn by the motor, and the reaction torque sensor is configured to detect a torque applied by the motor. The controller communicates with the sensor and the reaction torque sensor and is configured to control the motor. The controller is configured to compare the detected current drawn by the motor with the detected torque applied by the motor to verify that the detected torque is within an acceptable torque value range for the detected current drawn by the motor.

[0012] In some aspects, the control circuit includes a motor energy source in electrical communication with the motor. The motor energy source can be electrically isolated from the reaction torque sensor. The sensor can be configured to detect current drawn by the motor from the motor energy source.

[0013] In some aspects, the reaction torque sensor is configured to detect a mechanical property caused by the torque applied by the motor. The mechanical property may be strain.

[0014] In another aspect of the present invention, an instrument drive unit of a robotic surgical system includes a fixed plate, a first motor, a first reaction torque sensor, a first sensor, and a first controller. The first motor has a first drive shaft, and the first reaction torque sensor is arranged around the first drive shaft to fix the first motor to the fixed plate. The first reaction torque sensor is configured to detect the torque transmitted by the first motor. The first sensor is configured to detect the current drawn by the first motor. The first controller is configured to control the first motor. The first controller communicates with the first sensor and the first reaction torque sensor. The first controller is configured to compare the detected current drawn by the first motor with the detected torque transmitted by the first motor to verify that the detected torque is within an acceptable torque value range for the detected current drawn by the first motor.

[0015] In some aspects, the instrument drive unit includes a second motor, a second reaction torque sensor, and a second sensor. The second motor has a second drive shaft, and the second reaction torque sensor is arranged around the second drive shaft to fix the second motor to the fixed plate. The second reaction torque sensor is configured to detect the torque transmitted by the second motor. The second sensor is configured to detect the current drawn by the second motor. The first controller is configured to control the second motor. The first controller communicates with the second sensor and the second reaction torque sensor. The first controller is configured to compare the detected current drawn by the second motor with the detected torque transmitted by the second motor to verify that the detected torque is within an acceptable torque value range for the detected current drawn by the second motor.

[0016] In some aspects, the instrument drive unit includes a third motor, a third reaction torque sensor, a third sensor, and a second controller. The third motor has a third drive shaft, and the third reaction torque sensor is arranged around the third drive shaft to fix the third motor to the fixed plate. The third reaction torque sensor is configured to detect the torque transmitted by the third motor. The third sensor is configured to detect the current drawn by the third motor. The second controller is configured to control the third motor. The second controller communicates with the third sensor and the third reaction torque sensor. The second controller is configured to compare the detected current drawn by the third motor with the detected torque transmitted by the third motor to verify that the detected torque is within an acceptable torque value range for the detected current drawn by the third motor.

[0017] Further details and aspects of exemplary embodiments of the present invention are described in more detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Various aspects of the present invention are described below with reference to the accompanying drawings, which are incorporated into and constitute a part of this specification, in which:

[0019] Figure 1 is a schematic diagram of the user interface and robotic system;

[0020] Figure 2 yes Figure 1 A side cross-sectional view of an instrument drive unit of a robotic system;

[0021] Figure 3 It is along Figure 2 A cross-sectional view taken along section line 3-3;

[0022] Figure 4 yes Figure 2 a schematic diagram of a control circuit of an instrument drive unit; and

[0023] Figure 5 It shows the control Figure 1A flow chart of a method of an instrument driving unit. DETAILED DESCRIPTION

[0024] Embodiments of the present invention are now described in detail with reference to the accompanying drawings, wherein in each view of several views, the same reference numerals represent the same or corresponding elements. As used herein, the term "clinician" refers to a doctor, nurse or any other care provider, and may include support personnel. Throughout the specification, the term "proximal" refers to the device portion or its components closest to the clinician, and the term "distal" refers to the device portion or its components farthest from the clinician.

[0025] The present invention generally relates to an instrument drive unit (IDU) for a robotic surgical system, which includes a torque sensor (e.g., a primary sensor) that measures the torque applied by a motor and provides a torque signal to a controller that drives the motor. The IDU also includes an auxiliary sensor that measures the input of the motor to provide a verification signal to the controller. The controller compares the torque signal and the verification signal to ensure that the torque sensor is functioning properly. If the torque signal is outside an acceptable range of values ​​for a given verification signal, the controller generates a fault signal and / or stops the robotic surgical system.

[0026] As described in detail herein, the IDU includes a reaction torque sensor as the primary sensor. However, it is contemplated that the primary sensor may be an inline torque sensor.

[0027] refer to Figure 1 , shows a robotic surgical system 1, which includes a robotic system 10, a processing unit 30, and a user interface 40. The robotic system 10 generally includes a link 12 and a robot base 18. The link 12 movably supports a surgical instrument having an end effector or tool 20 configured to act on tissue. The link 12 can be in the form of an arm each having a plurality of parts 13. A part 13a of the plurality of parts 13 has an end 14 that supports an end effector or tool 20 configured to act on tissue. In addition, the end 14 of the part 13a can include an imaging device 16 for imaging a surgical site "S". Each of the plurality of parts 13 of the link 12 can be connected to each other around a joint 15. The user interface 40 communicates with the robot base 18 through the processing unit 30.

[0028] The user interface 40 includes a display device 44 configured to display a three-dimensional image. The display device 44 displays a three-dimensional image of the surgical site "S", which may include data captured by the imaging device 16 positioned on the end 14 of the component 13a and / or includes data captured by imaging devices positioned around the surgical operating room (e.g., an imaging device positioned within the surgical site "S", an imaging device positioned near the patient "P", an imaging device 56 positioned at the distal end of the imaging arm 52). The imaging device (e.g., the imaging device 16, 56) can capture visual images, infrared images, ultrasound images, X-ray images, thermal images, and / or any other known real-time images of the surgical site "S". The imaging device transmits the captured imaging data to the processing unit 30, which creates a three-dimensional image of the surgical site "S" from the imaging data in real time and transmits the three-dimensional image to the display device 44 for display.

[0029] The user interface 40 also includes input handles 42 that allow the clinician to manipulate the robotic system 10 (e.g., move the links 12, the ends 14 of the links 12, and / or the tools 20). Each input handle 42 communicates with the processing unit 30 to transmit control signals thereto and receive feedback signals therefrom. Each input handle 42 may include an input device that allows the surgeon to manipulate (e.g., clamp, grasp, fire, open, close, rotate, advance, slice, etc.) the tool 20 supported at the end 14 of the component 13a.

[0030] For a detailed discussion of the construction and operation of the robotic surgical system 1 , reference may be made to U.S. Patent Publication No. 2012 / 0116416, entitled “Medical Workstation.”

[0031] Also refer to Figure 2 and Figure 3, an instrument drive unit (IDU) 60 is disposed within or supported on the component 13a adjacent to the end 14. The IDU 60 is operably associated with the tool 20 coupled to the end 14 to manipulate the tool 20 in response to a tool signal transmitted by the tool from the processing unit 30. The IDU 60 includes a motor 62, each of which is operably coupled to a corresponding converter 64 and a corresponding reaction torque sensor 68. Each motor 62 rotates a drive shaft 63 in response to energy provided to the motor 62, the drive shaft extending through the main sensor or reaction torque sensor 68. The converter 64 converts the rotation of the drive shaft 63 of the motor 62 into a linear motion of a drive rod and / or cable (not shown). The converter 64 may be fixed to a fixed plate 61 of the IDU 60. The reaction torque sensor 68 measures the torque applied or transmitted to the converter 64 by the motor 62, and thus measures the force applied to the tool 20. The reaction torque sensor 68 is positioned around the drive shaft 63 of the motor 62 , and the motor 62 is fixed to the fixing plate 61 of the IDU 60 .

[0032] For a detailed discussion of the construction and operation of the reaction torque sensor 68, reference may be made to International Patent Application No. PCT / US15 / 14542, filed on February 5, 2015, entitled “Input Device Assemblies for Robotic Surgical Systems,” the entire contents of which are incorporated herein by reference.

[0033] refer to Figure 2 and Figure 3 , the IDU 60 includes one or more circuit boards 80, each of which includes a controller 126 provided in accordance with the present invention. As described in detail below, the controller 126 is detailed in terms of a single controller 126; however, it will be understood that the IDU 60 can have one or more controllers 126. The controller 126 communicates with one or more reaction torque sensors 68. As shown, the controller 126 communicates with a reaction torque sensor 68 via a lead 142 and communicates with another reaction torque sensor 68 via a lead 144. Each lead 142, 144 transmits a torque signal to the controller 126 that is indicative of the torque applied by the motor 62 as sensed by the corresponding torque sensor 68.

[0034] Although the torque applied by the motor 62 can be accurately measured by the reactive torque sensor 68, the torque applied by the motor 62 can also be calculated from the amount of current drawn by the motor 62. As described in detail below, this calculated torque can be used to verify whether the measured torque (i.e., the torque detected by the reactive torque sensor 68) is within an acceptable range of values ​​for the detected amount of current drawn by the motor 62. By verifying that the detected torque is within an acceptable range of values ​​for the detected amount of current, if the detected torque is outside of the acceptable range of values ​​for the detected amount of current, a fault may be generated and / or the motor 62 may stop. It will be appreciated that when the detected torque is outside of the acceptable range of values ​​for the detected amount of current, the reactive torque sensor 68 may have failed.

[0035] Continue to refer Figure 2 and Figure 3 , the IDU 60 includes sensors 152, 154 that provide verification signals to the circuit board 80. The sensors 152, 154 are each associated with a corresponding motor 62 to detect the amount of current drawn by the corresponding motor 62. Each sensor then sends a corresponding verification signal to the controller 126, which is indicative of the amount of current drawn by the corresponding motor 62. The controller 126 compares the verification signal to the torque signal to verify that the torque signal is within an acceptable value range relative to the verification signal.

[0036] It is contemplated that the sensors 152, 154 may detect torque and generate current from the detected current. In such embodiments, the controller compares the current of the verification signal to the torque signal to verify that the torque signal is within an acceptable range of values ​​relative to the verification signal.

[0037] refer to Figure 4 , the control circuit 120 compares the torque signal with the verification signal to verify that the detected torque is within an acceptable value range for the amount of current drawn by the motor 62. The control circuit 120 detects the reaction torque of the motor 62 and detects the amount of current drawn by the motor 62 to verify that the detected torque is within an acceptable value range for the amount of current drawn by the motor 62.

[0038] The control circuit 120 includes the motor 62, the reaction torque sensor 68, the voltage source 121, the filter 122, the amplifier 124, the controller 126 and the sensor 152. The reaction torque sensor 68 generates a torque signal, which is transmitted to the filter 122 by the lead 132. The filter 122 is a low pass filter for removing noise from the torque signal. The filter 122 transmits the filtered torque signal to the amplifier 124, which transmits the amplified filtered torque signal to the controller 126. The controller 126 determines the reaction torque of the motor 62 from the torque signal.

[0039] The controller 126 sends a control signal to control the motor 62 (e.g., the speed of the motor 62). The controller 126 can send a signal to the motor 62 or to the motor energy source 69 that provides energy to the motor 62. When the motor 62 draws energy from the motor energy source 69, the sensor 152 detects the amount of current drawn by the motor 62 from the motor energy source 69. The sensor 152 generates a verification signal indicating the amount of current drawn by the motor 62 and sends the verification signal to the controller 126.

[0040] The controller 126 compares the torque signal from the reaction torque sensor 68 to the verification signal from the sensor 152. First, the controller 126 generates an acceptable range of values ​​for the torque applied by the motor 62 from the verification signal. For example, when the verification signal indicates that the motor 62 is drawing 0.80 amps of current, the acceptable range of values ​​for the torque applied by the motor 62 is about 0.20 Nm to about .030 N-m. It will be appreciated that as the amount of current drawn by the motor 62 increases, the upper and lower limits of the acceptable range of values ​​for the torque applied by the motor increase. Additionally, as the amount of current drawn by the motor 62 increases, the acceptable range of values ​​may increase. If the torque signal is within the acceptable range of values, the controller 126 continues to send control signals instructing the motor 62 to continue rotating.

[0041] When the torque signal is outside of an acceptable range of values, the reaction torque sensor 68 may be malfunctioning and thus providing an inaccurate measurement of the torque applied by the motor 62, or the tool 20 may have hit an obstacle. Therefore, if the torque signal is outside of an acceptable range of values, the controller 126 may generate a fault signal and / or send a control signal to stop the rotation of the motor 62. The fault signal may be sent to the user interface 40 ( Figure 1 ) provides visual, audible, or tactile feedback to the interacting clinician.

[0042] refer to Figure 5 According to the present invention, a method 200 is disclosed for verifying torque measurements of a primary sensor or reaction torque sensor 68 of an instrument drive unit 60 using a sensor 152. Initially, the controller 126 receives a command signal to rotate the motor 62. In response to the command signal, the controller 126 sends a control signal to the motor 62 to rotate the drive shaft 63.

[0043] When the motor 62 is rotating, the motor 62 receives power from the motor energy source 69 ( Figure 4) draws current. The current is measured by the sensor 152 (step 210). The sensor 152 generates a verification signal indicative of the measured current (step 212) and transmits the verification signal to the controller 126 (step 214). Additionally, when the motor 62 is rotating, the reaction torque sensor 68 measures the torque applied by the motor 62 (step 220). The reaction torque sensor 68 generates a torque signal indicative of the measured torque (step 222) and transmits the torque signal to the controller 126 (step 224).

[0044] The controller 126 receives the verification signal (step 230) and generates an acceptable torque range that can be applied by the motor 62 for a given verification signal (step 240). As described above, the acceptable torque range is proportional to the current drawn by the motor 62. Next, the controller 126 receives the torque signal from the reaction torque sensor 68 and compares the torque signal with the acceptable torque range (step 250). If the torque signal is within the acceptable torque range, the controller 126 continues to send a control signal to the motor 62 to rotate the drive shaft 63 (step 255). Conversely, if the torque signal is outside the acceptable torque range, the controller 126 stops the rotation of the motor 62 by sending a control signal or stopping sending a control signal (step 260). Next, the controller 126 generates a fault signal indicating that the torque applied by the motor 62 is outside the acceptable torque value range. The fault signal can be audible, visual, tactile, or any combination thereof to alert the clinician that there is a fault.

[0045] Although several embodiments of the present invention have been shown in the accompanying drawings, the present invention is not intended to be limited thereto, as the present invention is intended to be as broad as the art will allow, and the specification is read in the same manner. Any combination of the above embodiments is also contemplated and within the scope of the appended claims. Therefore, the above description should not be interpreted as limiting, but merely as an illustration of a particular embodiment. Those skilled in the art will envision other modifications within the scope of the appended claims.

Claims

1. A method of verifying torque measurements of a torque sensor of an instrument drive unit of a robotic surgical system, the method comprising: detecting, with a first sensor, a first amount of current drawn by a first motor of the instrument drive unit; sending a first verification signal indicative of the first amount of current drawn by the first motor to a first controller; detecting torque transmitted by the first motor of the instrument drive unit; identifying an acceptable range of torque values ​​based on the first verification signal sent to the first controller; comparing a torque delivered by the first motor calculated from the detected first amount of current drawn by the first motor with the detected torque delivered by the first motor to verify whether the detected torque delivered by the first motor is within the acceptable torque value range based on the first verification signal; as well as Based on the first verification signal, the first motor is stopped when the sensed torque transmitted by the first motor is outside the acceptable torque value range.

2. The method according to claim 1, further comprising: The torque transmitted by the first motor is measured using a reaction torque sensor electrically isolated from the first motor, the reaction torque sensor transmitting a torque signal indicative of the torque transmitted by the first motor to the first controller which performs the comparison.

3. The method according to claim 1, further comprising: When the sensed torque is outside the acceptable torque value range, a fault signal is generated.

4. The method according to claim 3, wherein: Generating the fault signal includes providing feedback to the clinician, the feedback being audible, visual, tactile, or a combination thereof.

5. The method according to claim 1, further comprising: The verification signal is generated by the first sensor, and the first sensor transmits the verification signal to the first controller.

6. The method according to claim 5, further comprising: detecting, with a second sensor, a second amount of current drawn by a second motor of the instrument drive unit; sending a second verification signal indicative of the second amount of current drawn by the second motor to a second controller; detecting torque transmitted by the second motor of the instrument drive unit; identifying an acceptable range of torque values ​​based on the second verification signal sent to the second controller; comparing, based on the second verification signal, a torque delivered by the second motor calculated from the detected second amount of current drawn by the second motor with the detected torque delivered by the second motor to verify whether the detected torque delivered by the second motor is within the acceptable torque value range; as well as Based on the second verification signal, the second motor is stopped when the detected torque transmitted by the second motor is outside the acceptable torque value range.

7. A control circuit for a motor of an instrument drive unit of a robotic surgical system, the control circuit comprising: a first sensor configured to detect an amount of current drawn by a first motor of the instrument drive unit; a first reaction torque sensor configured to detect torque applied by the first motor; as well as a first controller in communication with the first sensor and the first reaction torque sensor and configured to control the first motor, the first controller being configured to, receiving a first verification signal indicative of the amount of current drawn by the first motor; receiving a first torque signal from the first reaction torque sensor; identifying an acceptable range of torque values ​​based on the first verification signal; as well as The torque delivered by the first motor calculated from the detected amount of current drawn by the first motor is compared with the detected torque delivered by the first motor to verify whether the detected torque delivered by the first motor is within the acceptable torque value range based on the first verification signal.

8. The control circuit according to claim 7, further comprising: a second sensor configured to detect an amount of current drawn by a second motor of the instrument drive unit; a second reaction torque sensor configured to detect torque applied by the second motor; as well as a second controller in communication with the second sensor and the second reaction torque sensor and configured to control the second motor, the second controller being configured to, receiving a second verification signal indicative of the amount of current drawn by the second motor; receiving a second torque signal from the second reaction torque sensor; identifying an acceptable range of torque values ​​based on the second verification signal; as well as The torque delivered by the second motor calculated from the detected amount of current drawn by the second motor is compared with the detected torque delivered by the second motor to verify whether the detected torque delivered by the second motor is within the acceptable torque value range based on the second verification signal.

9. The control circuit of claim 8, further comprising a motor power source in electrical communication with each motor, the motor power source being electrically isolated from each reaction torque sensor.

10. The control circuit according to claim 9, wherein: Each sensor is configured to detect a respective amount of current drawn by each motor from the motor energy source.

11. The control circuit according to claim 8, wherein: Each reaction torque sensor is configured to detect a mechanical characteristic caused by a torque applied by each respective motor.

12. The control circuit according to claim 11, wherein: The mechanical property is strain.

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