US-12616474-B2 - Robotic or powered surgical stapler with predictive stapling end stop

US12616474B2US 12616474 B2US12616474 B2US 12616474B2US-12616474-B2

Abstract

A powered or robotic surgical stapler includes a loading unit having an end effector with an anvil and staple cartridge. A drive shaft disposed in the loading unit is actuated by one or more motors. The drive shaft approximates the anvil and advances a knife and a sled to eject a plurality of staples from the cartridge. A position sensor and a torque or current draw sensor measure operation of the motor and a processor determines an initial peak in the torque or current. The processor then calculates a stop position from the drive shaft based on a motor position corresponding to the initial peak and actuates the drive shaft until it reaches the stop position, which occurs prior to the drive shaft reaching a mechanical limit of the drive shaft.

Inventors

David N. Fowler
Matthew S. Eschbach

Assignees

COVIDIEN LP

Dates

Publication Date: 20260505
Application Date: 20241011

Claims (17)

1 . A surgical robotic system comprising: a robotic arm including an instrument drive unit having a motor; a loading unit coupled to the motor, the loading unit including: an end effector having a first jaw and a second jaw; and a drive shaft movable through the end effector approximating at least one of the first jaw or the second jaw relative to each other; a sensor for measuring an actuation parameter; and a controller for: receiving the actuation parameter and determining a first position of the drive shaft based on the actuation parameter; calculating a stop position for the drive shaft that occurs prior to reaching a mechanical limit of the drive shaft, wherein the controller calculates the stop position by adding an offset value to the first position; and stopping the motor such that the drive shaft stops at the stop position.
2 . The surgical robotic system according to claim 1 , wherein the sensor is at least one of a motor torque sensor, a motor current sensor, or a strain sensor.
3 . The surgical robotic system according to claim 1 , wherein the actuation parameter is at least one of motor torque, current draw, or strain.
4 . The surgical robotic system according to claim 1 , wherein the instrument drive unit further includes a position sensor for measuring a position of the motor.
5 . The surgical robotic system according to claim 4 , further comprising a storage device storing a maximum threshold value and the offset value, wherein the storage device is accessible by the controller.
6 . The surgical robotic system according to claim 5 , wherein the controller determines the first position based on the position of the motor at a point in time when the actuation parameter exceeds the maximum threshold value.
7 . A powered surgical stapler comprising: a motor and a sensor for measuring an actuation parameter; a loading unit coupled to the motor, the loading unit including: an end effector having a first jaw and a second jaw; and a drive shaft movable through the end effector for approximating at least one of the first jaw or the second jaw relative to each other; and a controller for: receiving the actuation parameter and determining a first position of the drive shaft based on the actuation parameter; calculating a stop position for the drive shaft that occurs prior to reaching a mechanical limit of the drive shaft, wherein the controller calculates the stop position by adding an offset value to the first position; and stopping the motor such that the drive shaft stops at the stop position.
8 . The powered surgical stapler according to claim 7 , wherein the sensor is at least one of a motor torque sensor, a motor current sensor, or a strain sensor.
9 . The powered surgical stapler according to claim 7 , wherein the actuation parameter is at least one of motor torque, current draw, or strain.
10 . The powered surgical stapler according to claim 7 , further comprising a position sensor for measuring a position of the motor.
11 . The powered surgical stapler according to claim 10 , further comprising a storage device storing a maximum threshold value and the offset value, wherein the storage device is accessible by the controller.
12 . The powered surgical stapler according to claim 11 , wherein the controller determines the first position based on the position of the motor at a point in time when the actuation parameter exceeds the maximum threshold value.
13 . A system for controlling an end effector of a surgical stapling instrument, comprising: a stapling instrument including an end effector having an anvil and a staple cartridge with a plurality of staples, wherein at least one of the anvil or the staple cartridge are movable relative to each other; a drive shaft movable through the end effector to eject the plurality of staples; a motor for actuating the drive shaft; a sensor configured to measure an actuation parameter associated with at least one of the drive shaft or the motor during ejection of the plurality of staples; and a controller configured to: receive the actuation parameter from the sensor; detect multiple signal events corresponding to at least one of a peak or a valley in the actuation parameter, wherein the signal events are caused by staple ejections; estimate an end stop position for the drive shaft that occurs prior to reaching a mechanical limit of the drive shaft based on at least one of the signal events; continuously update the estimated end stop position based on at least another one of the signal events; determine a final end stop position based the estimated end stop position before the drive shaft reaches a mechanical limit; and generate a stop command to stop the motor when the final end stop position is reached.
14 . The system according to claim 13 , wherein the drive shaft is further configured to approximate at least one of the anvil or the staple cartridge relative to each other.
15 . The system according to claim 13 , wherein the controller is further configured to use a sequential Kalman filtering process.
16 . The system according to claim 13 , wherein the controller is further configured to calculate an error between a prior estimated end stop position and a current estimated end stop position.
17 . The system according to claim 16 , wherein the controller is further configured to calculate a gain value and update the estimated end stop position by adding a gain-multiplied difference between the prior estimated end stop position and the current estimated end stop position to the current estimated end stop position.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of, and priority to, U.S. Provisional Patent Application Ser. No. 63/590,814 filed on Oct. 17, 2023. The entire contents of the foregoing application are incorporated by reference herein. BACKGROUND Surgical robotic systems may include a surgeon console controlling one or more surgical robotic arms, each having a surgical instrument having an end effector. In operation, the robotic arm is moved to a position over a patient and the surgical instrument is guided into a small incision via a surgical access port or a natural orifice of a patient to position the end effector at a work site within the patient's body. The surgical instrument may be a surgical stapler having an articulatable end effector configured to clamp, fasten, and cut tissue. Such surgical staplers may also be powered handheld instruments. In powered handheld or robotic surgical staplers, a drive mechanism is advanced to approximate a pair of jaws of the end effector while simultaneously ejecting fasteners and cutting tissue. Robotic and powered handheld surgical staplers may stop firing (e.g., advancing the drive mechanism) by sensing an increase in motor current caused when the mechanism in the end effector can no longer advance due to contacting an end stop, e.g., end of a travel channel in the end effector. This increase in motor current is caused by the rapid increase in mechanical strain developed in the stapler due to pressing against a mechanical limit. Reaching the mechanical limit with the drive mechanism causes an undesired motion (e.g., twitching) in the end effector whereby the articulation angle of the end effector is changed as a result of the increased force in the system. SUMMARY The present disclosure provides a stapling loading unit including an articulatable end effector having a pair of jaw members, e.g., anvil and staple cartridge, that are closed and opened by advancing and retracting a drive mechanism actuated by one or more motors. The loading unit, which may be a single use or reusable unit, may be attached, either directly or using an adapter, to a robotic surgical system or a powered handheld surgical instrument. The adapter, loading unit, and/or staple cartridge may include a storage device configured to store one or more parameters pertaining thereto (e.g., length of a stapling cartridge, maximum torque, etc.), which may be provided as a maximum torque and/or current and/or force, that is used by the robotic surgical system or powered handheld surgical instrument to operate its motor(s) to control operation of the loading unit during stapling. The storage device may also provide torque or current draw thresholds for detecting an initial peak and a distance offset for determining the end stop and controlling the motor(s) based on the same. The distance required to reach end stop varies based on a variety of factors, such as the articulation angle of the end effector and the tissue thickness, so stopping after a set distance may not be desired even if the staple cartridge length is known, i.e., provided in the data read from the storage device. Thus, using an offset added to a determined distance during the stapling process provides a more accurate estimation of the end stop. The present disclosure provides a predictive algorithm, which may be embodied as software instructions stored in a non-transitory medium and executable by a processor. During a motor-powered actuation of the load unit (e.g., either in a powered handheld or robotic stapling system), one or more data signals are captured by the system, which may be analyzed in real time or after the firing. Data signals may include any motor parameter such as torque, speed, current, etc. as well as force or strain imparted on mechanical components of the loading unit, which may be measured via corresponding strain sensors. The algorithm is based on identifying a pattern that correlates to actions that happen within the staple cartridge during firing. Total travel distance by a drive mechanism from the start of the stapling process to end stop varies based on articulation angle and tissue thickness. Thus, the start of the process and the corresponding data pattern also varies. However, once the pattern is detected, the remainder of the firing process, including end stop follows a predictable sequence. The algorithm may also use the data stored on the storage device including the length of the staple cartridge and a distance offset value. The algorithm identifies the pattern based on the length of the staple cartridge, i.e., early in the firing, and predicts the location of the end stop based on the known nature of the pattern. In predicting where end stop will occur for each firing process, the firing process is stopped before the rapid increase in force as a result of the knife bar or drive shaft hitting the end of the channel slot and therefore the undesired motion (e.g., twitching of t