Medical image guided magnetic drive and navigation system for clinical application

Abstract

The invention provides a device for controlling a magnetic element and a system comprising the device. The device comprises a) a magnetic driving unit, wherein the magnetic driving unit comprises i) a built-in sensing module; ii) a plurality of magnetic sources, the plurality of magnetic sources are uniformly arranged around the built-in sensing module, and each magnetic source in the plurality of magnetic sources is inclined at an inclination angle and is separated from an adjacent magnetic source at an adjacent angle; and iii) an adjustment mechanism connected to each of the plurality of magnetic sources to adjust the tilt angle and the adjacent angle to achieve a desired magnetic field; and b) a robot platform which is used for installing the magnetic driving unit and providing flexible attitude control for the magnetic driving unit.

Description

Technical Field

[0001] The present invention relates to an integrated system that combines a mobile magnetic drive unit and an imaging tool for remotely controlling a magnetic robot in vivo. The mobility of the robotic platform ensures sufficient workspace for magnetic drive and target tracking in clinical applications. Background Art

[0002] Magnetic robots have great potential in minimally invasive medical applications. Due to the inherent advantages of magnetic fields, such as less distortion when penetrating the human body, harmlessness to biological tissues, and efficient wireless energy transmission, medical magnetic robots have been applied to various clinical tasks, including but not limited to tissue sampling, drug delivery, and real-time diagnosis. To achieve dexterous magnetic manipulation, magnetic manipulation systems that can perform multi-degree-of-freedom magnetic control are now available. Magnetic manipulation systems can be divided into two categories according to the magnetic source used: permanent magnet systems (PMS) and electromagnetic systems (EMS).

[0003] For the first type of system, a robotic platform is usually used to control the posture of the permanent magnet motor to generate the required magnetic field, which is a safe and effective way to drive various magnetic robots. However, it is difficult for such systems to generate complex or rapidly changing modulated magnetic fields. In addition, the rapidly decaying magnetic field limits the depth of the drive, and the magnetic field is difficult to turn off. In the EMS system, the required magnetic field is controlled by changing the current provided. By arranging multiple electromagnets around the workspace, dexterous magnetic operations from micrometer-level robots to centimeter-level robots can be achieved. Controlling the magnetic field with the provided current, a stronger magnetic field will lead to difficulties in temperature control and risk control. The workspace is usually surrounded or semi-surrounded by electromagnets, which limits this technology to benchtop experiments. EMS can generate more controllable magnetic fields, but it occupies a large area and requires support from subsystems such as temperature monitoring and cooling units and current control units. Due to the nonlinear behavior of the soft iron core, the magnetic field it generates is also difficult to estimate. The present invention includes a mobile electromagnetic drive unit, which uses a robotic platform to bring the electromagnet to a larger workspace and avoid interference with the imaging tool. The flexibility of the system is determined by the number of electromagnets and the controllable degrees of freedom of the robotic platform. For different magnetic field generation requirements, the flexibility of the magnetic drive unit can be designed accordingly.

[0004] There are now a variety of imaging and tracking methods for in vivo magnetic robot drive and navigation to bridge the gap between benchtop experiments and clinical applications. Visual servoing is usually performed using cameras or stereoscopes in laboratory environments, but this tracking tool is difficult to use in clinical settings. There is a need for alternative positioning and imaging methods that can be used in actual scenarios where the working environment does not allow line of sight. X-rays are a common medical imaging method that can capture information inside the human body with sufficient accuracy and refresh rate. Ultrasonic imaging is another effective and efficient imaging tool that can obtain cross-sectional views of the imaging environment with micron-level accuracy. Magnetic positioning is a tracking method that can extract the absolute position and orientation of a magnetic robot based on the magnetic field generated by the embedded magnets. To achieve precise operation, one or more medical imaging tools can be integrated into the imaging and tracking unit in the present invention. Multiple imaging and tracking fusion methods are embedded in the main control unit to achieve different imaging modes.

[0005] The driving and navigation methods of medical robots include hydraulic driving, wire driving and magnetic driving. In previous work, scientists have achieved precise navigation in the body by adjusting the pressure inside the medical robot to control the shape and movement of the robot. By adjusting the traction force of the driving line, the wire-driven robot can achieve functions such as steering, buckling and stiffness adjustment. Magnetic drive, as a bio-friendly driving method with low distortion when passing through low magnetic permeability structures, is widely used in wirelessly controlled cable-free medical robots in the body. In the present invention, the driving magnetic field is generated by a mobile magnetic source with a reconfigurable design. It can meet the needs of various magnetic field generation methods by adjusting the relative position of each magnetic source or increasing the total number of magnetic sources.

[0006] Magnetic medical robots can be divided into tethered and untethered medical robots. Tethered robots are developed from catheter technology, which is a widely used treatment method in medical practice, such as cardiac ablation, tissue sampling, cell / drug delivery, and vascular disease treatment. Tethered capsule robots are designed for gastrointestinal examination and real-time diagnosis. Untethered robots are another controllable type that can better adapt to tortuous environments and perform medical tasks in hard-to-reach areas in the human body. Remote wireless control of untethered robots requires a more powerful control algorithm and precise imaging tracking methods. In addition, the advanced and complex motion principles of robots have higher requirements for magnetic field generation, often requiring stronger and more complex magnetic fields. Untethered robots are widely used in intravascular applications or gastrointestinal treatments that are difficult to access non-invasively with standard medical tools. Magnetic robots for different medical applications need to be endowed with multiple functions and have different requirements for magnetic field control. There are already studies on magnetically driven robots for gastrointestinal monitoring or eye microsurgery. Torque-driven robots, such as spiral robots or rolling robots, will have more efficient movement and smaller size. In addition, robots with functions such as drug delivery or tissue sampling require specific magnetic field designs to accurately trigger the mechanism. The system of the present invention will generate complex and controllable magnetic fields in a large workspace with an optimized structure. The combination of smart magnetic actuation with real-time posture and environmental information can be applied to clinical applications such as long-distance drug delivery, thrombus removal, full gastrointestinal monitoring, and treatment procedures of the distal vascular system.

[0007] U.S. Patent No. 7,311,107B2 relates to a device and control system for driving and positioning a vehicle in the body by detecting and manipulating the strength and direction of the vehicle's electromagnetic field vector. The patent mentions that a soft magnetic core can be installed in the electromagnet.

[0008] Another patent, numbered US 6,311,082 B1, discloses a movable bed system for supporting patients, wherein a group of electromagnets are mounted on a curved shell under the bed, and a magnetic field or a magnetic field gradient is provided by appropriately energizing some of the electromagnets.

[0009] U.S. Patent No. 6,148,823 relates to a system for controlling magnetic elements in the body using a gap ring magnet, the system comprising a pair of mutually attractive opposing magnets separated by a gap. The magnets are preferably permanent magnets connected by a magnetic flux loop. The patent also discloses that the magnets can be mounted on a movable support, and the system has a portable support for supporting a patient and an X-ray imaging device.

[0010] U.S. Patent No. 6,216,026B1 relates to an invention of controllable magnetic moment, which is suitable for navigating a catheter or a flexible endoscope in a patient's body when used in conjunction with MRI. The disclosed embodiment arranges coils in three different axial directions, so that a variety of magnetic moment combinations can be provided by changing the current input of the three coils.

[0011] US Patent No. 8,830,648B2 discloses a magnetic drive system called Octomag, which has two sets of electromagnetic coils, each set containing four electromagnets or permanent magnets, and can control a millimeter-scale robot to move with five degrees of freedom in a small working space, such as the cavity of a human eye.

[0012] Another device is disclosed in US Pat. No. 8,041,411 B2. This patent discloses a magnetic control system that mounts a circumferentially movable magnet on a curved arm and uses X-ray images to navigate the magnetic element.

[0013] U.S. Patent No. 8,027,714B2 introduces a device consisting of eight magnetic coils with magnetic cores mounted on two opposing spherical shells. This embodiment allows a servo motor to position the relative distance between the two sets of electromagnets and introduces radar as an imaging method to avoid radiation such as X-rays. This embodiment can generate a magnetic field strength of B = 0.04T-0.15T and a magnetic field gradient of 1.6T / m to 3.0T / m, thereby exerting sufficient force and guiding direction to move a magnetically responsive catheter tip. Summary of the invention

[0014] The present invention provides a device for tracking a magnetic element. In one embodiment, the device comprises: a) a magnetic drive unit, the magnetic drive unit comprising: i) a built-in sensing module; ii) a plurality of magnetic sources, the plurality of magnetic sources being uniformly arranged around the built-in sensing module, each of the plurality of magnetic sources being tilted at an inclination angle and separated from an adjacent magnetic source at an adjacent angle; and iii) an adjustment mechanism, the adjustment mechanism being connected to each of the plurality of magnetic sources to adjust the inclination angle and the adjacent angle to achieve a desired magnetic field; b) a robot platform, the robot platform being used to mount the magnetic drive unit and provide dexterous posture control of the magnetic drive unit.

[0015] The present invention also provides a system for tracking magnetic elements. In one embodiment, the system includes: a) a magnetic element; b) one or more devices of the present invention; c) a built-in imaging system (2); and d) a computer processor; the computer processor is used to execute an algorithm, which cooperates with the one or more devices and the built-in imaging system (2) and includes the following steps: i) receiving posture information of components in the system; ii) calculating the expected trajectory of the one or more devices of the present invention and the built-in imaging system (2) according to a user's command to operate the magnetic element before operation; iii) analyzing the real-time position of an object in the field of view of the built-in imaging system during the operation; and iv) detecting potential collisions using a predictive control strategy based on the real-time position to adjust the expected trajectory. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram showing the system of the present invention performing magnetic control on a magnetic element within a patient's body.

[0017] Figure 2 The working flow chart of the system of the present invention is shown.

[0018] FIG. 3( a ) illustrates an embodiment of an electromagnetic source design of the present invention, showing adjacent angles.

[0019] FIG. 3( b ) shows an embodiment of the electromagnetic source design, showing the tilt angle.

[0020] FIG. 3( c ) illustrates an embodiment of the present invention, showing a reconfigurable coil support structure design for a single coil.

[0021] FIG. 3( d ) shows an embodiment of the present invention, which adjusts the posture of a single electromagnet by a rotary motor.

[0022] FIG. 3( e ) shows a posture adjustment device according to an embodiment of the present invention, which is composed of a linear motor 28 , a universal ball joint 29 and a serial manipulator 30 .

[0023] FIG. 3( f ) shows a posture adjustment design according to an embodiment of the present invention, which uses a single linear motor to adjust the posture of a single electromagnetic coil.

[0024] FIG. 3( g ) shows the core tip designs of four embodiments of the present invention.

[0025] FIG. 3( h ) shows the shape designs of electromagnetic coils according to two embodiments of the present invention.

[0026] FIG. 4( a ) shows a cross section of an electromagnetic coil cooling design according to one embodiment.

[0027] FIG. 4( b ) shows a cooling channel design according to an embodiment.

[0028] Figures 4(c) to 4(f) Four embodiments of the magnetic core cooling system of the present invention are shown.

[0029] FIG5(a) shows a design of a serial robot arm, which realizes motion control by using two serial manipulators 36, 37 to control in-plane motion and two other serial manipulators to control out-of-plane motion.

[0030] FIG5( b ) shows a lever-structured robotic platform design that has sufficient load tolerance to support a larger magnetic source.

[0031] FIG. 5( c ) shows the robot platform structure according to an embodiment of the present invention.

[0032] FIG. 5( d ) shows an embodiment of the present invention that uses a movable magnetic source to achieve multi-point magnetic field control.

[0033] FIG6( a ) shows the design of a built-in tracking system according to an embodiment of the present invention. The ultrasonic probe is fixed by a micro parallel robot arm, and the micro parallel robot arm can control the six degrees of freedom of the ultrasonic imaging plane.

[0034] The embodiment shown in FIG6( b ) has a built-in tracking system design using one rotational degree of freedom controlled by a rotational motor.

[0035] Figures 7(a) to 7(c) Embodiments of a magnetic isolation shield design 50 and a magnetic field monitoring system design 51 are shown.

[0036] Figure 8(a) shows a subsystem arrangement that enables magnetic drive and imaging tools to share the same human-sized workspace. The subsystem is mounted on rails 58, 54 to achieve stable ground movement around the bed.

[0037] FIG8( b ) shows details of the magnetic source design of the present invention, which includes four coils and a built-in ultrasonic imaging tool 59 . DETAILED DESCRIPTION

[0038] The present invention provides an integrated magnetic system for driving and navigating magnetic elements in vivo, the system comprising: a mobile magnetic source for generating a controllable magnetic field in a large workspace; an imaging and tracking system for locating targets and acquiring in vivo information; a central processing system for implementing control algorithms and data analysis; a human-machine interface that translates operator commands into control signals; and a support bed equipped with medical equipment and capable of reflecting the patient's condition. The magnetic source is controlled by a robotic platform that enables movement of a heavy-load magnetic source in a human-scale workspace. The required magnetic field is generated by the robotic platform and the current provided. Motion control of the imaging and tracking system implements a human-sized tracking space identical to the magnetic drive system, and includes multiple imaging modes and tracking tools.

[0039] Based on the existing research, an object of the present invention is to provide an integrated system combining magnetic field drive and medical imaging tools for in vivo clinical applications of manipulating and navigating medical magnetic robots in large workspaces. The magnetic field required in the large workspace is generated by the cooperation of the robot platform and the magnetic source. In order to meet the needs of clinical applications, an imaging and tracking subsystem is combined with the system to locate the controlled object and image the in vivo information.

[0040] A feature of the present invention is its mobility to ensure successful coordination of magnetic drive and imaging modalities. For different medical applications, the present invention can be adjusted accordingly to generate specific control magnetic fields without interfering with imaging and tracking quality. In addition, the magnetic source can be moved to the vicinity of the controlled object to generate the required drive magnetic field to avoid current overshoot and soft iron core saturation. The present invention has a human-sized workspace and focuses on a specific area without using heavy magnetic sources.

[0041] A set of reconfigurable magnetic sources generates a magnetic field. In one embodiment, the magnetic source is made of a permanent magnet. A posture control device generates the required magnetic field to control the direction of the magnet. A position control mechanism can be designed accordingly according to the shape of the permanent magnet and the required driving magnetic field. By adjusting the movement mode of each magnetic source, a driving magnetic field such as a rotating magnetic field or an oscillating magnetic field can be achieved. In one embodiment, the magnetic source is an electromagnetic coil. The required magnetic field can be generated in coordination with the robot platform and the current provided. According to the superposition principle, the magnetic field at the selected position is the sum of the magnetic fields of each magnetic source. By changing the relative position of each electromagnet, specific magnetic fields including but not limited to gradient-dominated fields, torque-dominated fields, gradient-free fields and torque-free fields can be achieved.

[0042] The electromagnetic source assembly has a reconfigurable design to accommodate the relative structural adjustment device. In one embodiment, the magnetic source is composed of a plurality of permanent magnets that can rotate and translate to generate the desired magnetic field. In one embodiment, the magnetic source is composed of a set of electromagnetic coils. The current provided, its direction and its relative position can be adjusted to generate the desired magnetic field. In one embodiment, the core of the magnetic coil is made of soft iron with internal cooling channels. The tip shape design can meet different magnetic field generation requirements.

[0043] In one embodiment, a temperature control subsystem for protecting the electromagnetic source includes a cooling module, a temperature sensing module and a circulation module. In one embodiment, the cooling module includes an external cooling device located on the surface of the coil. In one embodiment, the internal cooling is designed in the core of the electromagnetic core. Designing a cooling channel inside the soft iron core can better control the internal temperature. When the external cooling unit cannot provide sufficient temperature control, an internal cooling structure designed by finite element analysis will be adopted. The present invention includes a numerical method for simulating the generated magnetic field to overcome the nonlinear problems caused by the internal cooling coil. In order to better provide the real-time status of the coil, the present invention includes a six-point temperature sensing deployment method. In one embodiment, the circulation speed and cooling temperature of the coolant are adjusted according to the feedback sensed temperature.

[0044] For electromagnetic sources, the present invention includes a method for spatially arranging electromagnetic coils to generate a desired magnetic field without affecting accessibility and compatibility. In one embodiment, the coils are symmetrically arranged with their axes coinciding at a point so that their focal points have maximum field strength. In one embodiment, the design of multiple focal points achieves multiple local maximum magnetic fields. In one embodiment, the coils are arranged to generate a uniform magnetic field. In one embodiment, the coils are arranged to generate a uniform gradient field.

[0045] The present invention includes a current regulation device for providing a high-power four-quadrant power supply to an electromagnetic coil. The current regulation subsystem includes a bidirectional DC power supply, an H-bridge circuit supported by an H-bridge driver circuit, and a microcontroller for generating a high-frequency control pulse width modulation (PWM) signal.

[0046] The present invention includes a method for designing a magnetic drive system structure that can avoid collision with a hospital bed and interference with an imaging and tracking system. According to the method of the present invention, the workspace can be expanded according to different experimental subjects and is compatible with the doctor's examination.

[0047] In one embodiment, a bedside placement structure is designed. The structure is compatible with the C-arm imaging module and provides sufficient access space for doctors to check. In one embodiment, to better adapt to the operating room environment, the magnetic drive system is installed on a U-shaped slide rail. In one embodiment, multiple groups of mobile magnetic sources can be designed to focus on multi-point applications or optimize the magnetic field generation at a single point.

[0048] The present invention provides a mobile magnetic source supported by a robot platform, the magnetic field generated by the mobile magnetic source has multiple degrees of freedom (DOF). Its mobility can be achieved in different forms. In one embodiment, a serial robot arm supports the magnetic source, and the serial robot arm has a smaller footprint but more stringent load requirements. In one embodiment, the present invention provides a three-DOF robot structure composed of a spiral table to enhance load and accuracy. In one embodiment, the posture of the magnetic source is adjusted by a side-mounted parallel robot structure. Its mobility can be achieved in different forms.

[0049] The present invention includes a hybrid medical imaging system to integrate different types of tracking and imaging modules. In one embodiment, a design combining an internal imaging system and a mobile C-arm is used to achieve controlled target tracking in a large workspace. In one embodiment, the internal tracking system is combined with a mobile magnetic source. This design ensures accurate tracking performance in a large workspace without complex structural design or additional sensor support modules. In one embodiment, an external sensor system and an internal tracking system are combined to provide information for in vivo magnetic robotic navigation.

[0050] The present invention provides a magnetic field hybrid modeling method, which can estimate the magnetic field in the working space under different electromagnetic coil designs. The prior art uses dipole model, variant dipole model and analytical eddy current model magnetic field modeling technology. The modeling method of the present invention uses a learning-based mapping method to combine finite element method data and calibration data to estimate the magnetic field generated under different shape designs and core designs.

[0051] The present invention provides a magnetic field prediction method for a movable magnetic source, the method taking into account the transition period between each position. Implementation of the method allows the magnetic field to continuously affect the controlled object. One challenge of the magnetic drive system of the present invention is to accurately predict the magnetic field.

[0052] The integrated system of the present invention combines a mobile magnetic source and a medical imaging tool to provide precise magnetic navigation and actuation for clinical applications. The magnetic system can move with the controlled target and navigate magnetic elements over long distances without using large currents or superconducting materials. The synergy between the imaging system and the magnetic source can provide real-time posture and in vivo information of the controlled target. To connect medical equipment, the present invention provides a design for a multifunctional hospital bed. In one embodiment, a sensing and tracking module is embedded in the hospital bed to locate the controlled object. In one embodiment, the hospital bed is combined with an electrocardiogram (ECG) and a ventilator.

[0053] The present invention provides an integrated navigation system combining mobile magnetic drive and medical imaging tools for manipulation of magnetic elements for in vivo applications. In one embodiment, the system includes: (a) a mobile magnetic source controlled by a robotic platform to achieve magnetic field generation in a large workspace in the patient's body and avoid mutual interference with the imaging system; (b) an imaging system for providing the position of the controlled element and in vivo information in a human-sized workspace, the built-in sensing module and the external imaging system work together to provide accurate positioning for control and diagnosis, the built-in sensing module moves with the magnetic source to actively track the controlled element, and the external imaging system is controlled by a mobile structure to provide imaging and positioning information of the patient's body; (c) a robotic platform with a magnetic source that can be stably moved around the bed. (d) an integrated bed compatible with medical monitoring equipment that provides patient status to a central processing module; (e) a central processing module consisting of a host computer and a data acquisition (DAQ) microcontroller that processes feedback data from the imaging system and issues commands to the motion control unit and current control unit; and (f) a human-machine interface that translates operator commands into specific motor and current signals and sends the commands to the corresponding subsystems, with detailed operation processes and the status of the controlled elements visible on a display.

[0054] In one embodiment, the motion control of the magnetic source described in the present invention is achieved through a composite lever structure that can simultaneously allow multiple degrees of freedom and heavy loads. The magnetic source is supported by a serial manipulator, and the serial manipulator is located on a base joint, so that the weight is transferred to the base instead of being supported by the serial manipulator. The serial manipulator serves as a fulcrum, and the far end of the lever is driven by a linear motor that controls rotational motion in a control plane. The linear motor connected to the magnetic source controls the distance between the magnetic field and the patient.

[0055] In one embodiment, the imaging system of the present invention is collaboratively composed of motion control, a built-in imaging module and an external (external) imaging module. A collaborative motion control method of the present invention can avoid interference and collision caused by a magnetic drive method. The built-in tracking device includes but is not limited to ultrasonic imaging, photoacoustic imaging, a magnetic sensor array, a camera and infrared imaging. The built-in imaging tools include but are not limited to X-rays, fluoroscopy, fluorescence imaging and laser-induced fluorescence.

[0056] In one embodiment, the ground track around the hospital bed of the present invention is used to support and control the posture of the magnetic source. The arrangement of the track can be two independent tracks or a U-shaped track that can cover both ends of the bed. The number of the magnetic sources can be more than two without affecting the imaging module and the patient.

[0057] In one embodiment, the electromagnetic source of the present invention is controlled by a current control unit, which consists of three parts: a bidirectional power supply unit, an H-bridge regulation unit and a microcontroller unit.

[0058] In one embodiment, the magnetically controlled magnetic elements of the present invention include magnetic catheters, cable-free magnetic robots, magnetic swarm particles, and magnetic endoscopes.

[0059] In one embodiment, the human-machine interface of the present invention is an integrated module combining a joystick, pedals, a steering wheel and 3D glass, and the human-machine interface is embedded with voice control, gesture control algorithm and augmented reality technology.

[0060] In one embodiment, the imaging and tracking device of the present invention collects multi-dimensional information and transmits it to a central processing system, wherein the information includes in vivo information, absolute target posture, temperature information, magnetic field information, and cross-sectional views of the patient's body. The data is fused by the central processing system to generate the required magnetic field and control the movement of the robotic structure.

[0061] The present invention also provides a method for controlling an integrated mobile magnetic drive and imaging system, which can realize simultaneous positioning and navigation of magnetic elements. In one embodiment, the method includes: (a) the imaging module provides the position information of the controlled element, the position of the magnetic source and the structure information of the robot platform to the central processing system; (b) processing data fusion, required magnetic field calculation, operation command translation and motion control of the robot structure on the central processing system, and sending control signals to the distributed processing units of each subsystem; (c) moving the magnetic source near the magnetic element and calculating the current that can generate the required magnetic field, and the temperature control unit controls the cooling and coolant circulation in the internal and external cooling channels; (d) the imaging tool motion control unit moves the external imaging device to move the magnetic element in the field of view, and the current position of the element is fed back to the central processing system; (e) updating the required current and the movement of the magnetic source on the central processing unit; (f) the human-machine interface updates the operator's operation command, and translates the command into a specific magnetic field and motion requirements and sends it to the central processing system; (g) patient information, magnetic element status and in vivo information are displayed on the screen to assist operation.

[0062] In one embodiment, the temperature control system of the present invention consists of two units, wherein the internal circulation channel is embedded in the soft iron core, and temperature sensors are installed at the inlet and outlet; and the external circulation channel is attached to the surface of the electromagnetic coil, and temperature sensors are embedded on the surface of the iron core, the surface of the coil, and the inlet and outlet of the circulation channel.

[0063] In one embodiment, the internal cooling system of the present invention is designed to balance the overall volume and heat generation, and its channels are distributed inside the core.

[0064] In one embodiment, the present invention provides a magnetic field modeling method, which is applicable to unconventional electromagnetic coils with soft iron cores, internal structures, and customized electromagnetic coil shapes, and its simulated magnetic field is calibrated with manually measured magnetic fields through a learning-based modeling method.

[0065] In one embodiment, the built-in imaging system of the present invention includes one or more types of tracking tools, such as ultrasound imaging, magnetic sensor arrays, and cameras, and its ultrasound probe is controlled by a position control mechanism, such as a parallel robot or a serial robot.

[0066] The present invention further provides a hierarchical control method to coordinate motion control and magnetic field generation to avoid collision and interference between the imaging system and the driving system, wherein the first level is safety distance control and collision control, and the second level is magnetic field generation control and imaging field of view control.

[0067] In one embodiment, the controlled magnetic elements include, but are not limited to, magnetic catheters, cable-free magnetic microrobots, and magnetic capsule endoscopes.

[0068] The present invention further provides an electromagnetic shielding design made of multiple layers of materials with different magnetic permeabilities, whose electromagnetic shape is intended to confine the magnetic field within the working space.

[0069] The present invention also provides a magnetic field monitoring system design with different sensors, including but not limited to magnetic sensors, temperature sensors and humidity sensors; the sensors are located relatively far away from the working space and can observe the real-time status of the electromagnetic source.

[0070] The present invention provides a device for controlling a magnetic element. In one embodiment, the device comprises: a) a magnetic drive unit, the magnetic drive unit comprising: i) a built-in sensing module; ii) a plurality of magnetic sources, the plurality of magnetic sources being uniformly arranged around the built-in sensing module, each of the plurality of magnetic sources being tilted at an inclination angle and separated from an adjacent magnetic source at an adjacent angle; and iii) an adjustment mechanism, the adjustment mechanism being connected to each of the plurality of magnetic sources to adjust the inclination angle and the adjacent angle to achieve a desired magnetic field; b) a robot platform, the robot platform being used to mount the magnetic drive unit and provide dexterous posture control of the magnetic drive unit.

[0071] In one embodiment, the built-in sensor module includes one or more components selected from the following: a camera, a 2D / 3D ultrasonic probe, an X-ray generator, an electrostatic sensor, a magnetic sensor, a fluorescence sensor, an optical transmissometer, a force sensor, a grating sensor, a photoacoustic probe, a laser speckle imaging, an infrared thermal imaging camera, a radio frequency probe or a humidity sensor. In another embodiment, the ultrasonic probe is regulated by a position control mechanism, and the position control mechanism is selected from a parallel manipulator or a serial manipulator control.

[0072] In one embodiment, the adjustment mechanism includes a configuration selected from the following: a) two linear motors (17) and two universal ball joints (19); b) a four-bar linkage consisting of four serial manipulators (26, 27); c) a linear motor (28), a universal ball joint (29) and a serial manipulator (30); and d) a linear motor (31) or a rotary motor.

[0073] In one embodiment, the plurality of magnetic sources comprise electromagnets or permanent magnets. In another embodiment, the electromagnet comprises a soft iron core, copper wire and a temperature control module for controlling the temperature of the soft iron core, the temperature control module comprising: a) a cooling channel having an inlet and an outlet, the cooling channel surrounding the soft iron core or located within the soft iron core; b) a cooled heat exchange fluid entering and exiting the cooling channel from the inlet and the outlet, respectively; and c) temperature sensors mounted at the inlet, the outlet and embedded in or located within the soft iron core. In a further embodiment, the soft iron core has a stepped design. In another embodiment, the tip of the soft iron core is cylindrical, conical, stepped or circular.

[0074] In one embodiment, the current supplied to the electromagnet is controlled by a current control unit to achieve a desired magnetic field, and the current control unit includes a bidirectional power supply unit, an H-bridge regulation unit and a microcontroller unit.

[0075] In one embodiment, the magnetic element is selected from one or more of the following: a cabled magnetic robot, a magnetic catheter, a magnetic guidewire, a magnetic needle, a magnetic sleeve, a magnetic soft robot, a magnetic continuous robot, a cable-free magnetic robot, a magnetic spiral swimmer, a magnetic roller, a magnetic clamp, a magnetic surgical tool, a magnetic endoscope or a magnetic capsule endoscope.

[0076] In one embodiment, the device further comprises a magnetic isolation shield composed of layers of materials of different magnetic permeabilities.

[0077] In one embodiment, the robotic platform includes a configuration for dexterous posture control of the magnetic drive unit, the configuration being selected from one or more of the following: a) two serial manipulators (36, 37) for movement within a control plane, and two serial manipulators (38) for movement outside a control plane; b) a first linear drive mechanism (39) supported by a first serial manipulator (40) and a second serial manipulator (42), the second serial manipulator being connected to a second linear drive mechanism (41); and c) a rotary motor (47) and a linear motor (48).

[0078] In one embodiment, the robotic platform comprises a guide rail (43) for stabilizing the translational movement of the device.

[0079] The present invention also provides a system for controlling a magnetic element. In one embodiment, the system comprises: a) a magnetic element; b) one or more devices of the present invention; c) a built-in imaging system (2); and d) a computer processor; the computer processor is used to execute an algorithm, the algorithm cooperates with the one or more devices and the built-in imaging system (2) and comprises the following steps: i) receiving posture information of components in the system; ii) calculating the expected trajectory of the one or more devices and the built-in imaging system (2) according to the user's command to operate the magnetic element before operation; iii) analyzing the real-time position of an object in the field of view of the built-in imaging system during the operation; and iv) detecting potential collisions using a predictive control strategy based on the real-time position to adjust the expected trajectory.

[0080] In one embodiment, the system further includes a hospital bed embedded with a sensing and tracking module.

[0081] In one embodiment, the built-in imaging system is integrated with a mobile C-arm.

[0082] In one embodiment, the magnetic element is selected from a magnetic catheter, a cable-free magnetic microrobot, or a magnetic capsule endoscope.

[0083] In one embodiment, the plurality of magnetic sources include electromagnets, and the current supplied to the electromagnets is controlled by a current control unit to achieve a desired magnetic field. The current control unit includes a bidirectional power supply unit, an H-bridge regulation unit, and a microcontroller unit.

[0084] In one embodiment, the algorithm further comprises a hierarchical control method to coordinate the motion of the system and the magnetic field generation, the hierarchical control method comprising a first level to control safety distance and collision prevention; and a second level to control magnetic field generation and imaging field of view.

[0085] In one embodiment, the system further comprises a module for a user to intervene in and override the control of the system over the algorithm.

[0086] Figure 1A schematic diagram showing an embodiment of the integrated magnetic drive and navigation system of the present invention. The system includes a mobile magnetic control device 1 with a human-sized workspace, an imaging device 2, a support bed 3 for a patient 4, a central processing system 5, a visualization system 6, a human-machine interface 7 and a power control unit 8. According to the present invention, the mobile electromagnetic source 1 is used to drive an element in the patient 4. Its mobility is achieved by a robot platform including 11, 12, 13 and 14. 11 is a linear track motor that moves the magnetic source within the human scale. 12 and 13 achieve local magnetic source adjustment. The magnetic motor mounted on 14 includes a group of magnetic sources. In one embodiment, a group of electromagnets is used to generate a controllable magnetic field, such as a uniform field or a gradient field. The external medical imaging subsystem movement mechanism 2 is intended to provide human-sized tracking and imaging capabilities. The imaging system has a base joint 21, a rotating waist joint 22, two serial manipulators 23 and 24, and a C-arm 25 at the end.

[0087] exist Figure 1 In the embodiment shown, the central processing module 5 controls the movement and magnetic field generation of the magnetic drive subsystem 1. In one embodiment, the central processing module is composed of a main computer and a microcontroller. In one embodiment, a posture control device is used to control a permanent magnet that generates a desired magnetic field. In one embodiment, the current supplied to the electromagnet is controlled to generate the desired magnetic field. The processing module collects sensor data and generates the desired magnetic field. In the current embodiment, a joystick 7 facilitates the operator to operate in a human-machine interface embedded with magnetic field control and motion control algorithms. Other human-machine interface embodiments, such as touch screens, keyboards, posture control, and voice control, are also applicable to the present invention. The system includes a power supply unit 8 to provide power to the robot platform and the magnetic source. The imaging device 2 has built-in structures, and these mobile support structures allow multi-degree-of-freedom control of the imaging area.

[0088] Figure 2A schematic diagram showing the workflow of the integrated system. The entire system consists of five modules: 1) a mobile magnetic drive subsystem that receives commands from a central processing module and generates a precise magnetic field in a large workspace, 2) an imaging and tracking subsystem that provides posture information and in-vivo information of the patient, 3) a central processing module that implements control and tracking algorithms and coordinates the system to avoid interference and collision, 4) a human-machine interface that facilitates access and reduces the workload of doctors, and 5) a bed equipped with medical equipment that provides patient status. In the mobile magnetic drive subsystem, a robotic platform is responsible for controlling the posture of the magnetic source and bringing the driving magnetic field to a human-sized workspace. In one embodiment, the magnetic source includes a set of electromagnetic coils that generate the required magnetic field based on the current provided. The magnetic drive subsystem translates the required magnetic field into current and motion commands and sends this information to different modules. A temperature control module is integrated into the drive subsystem to avoid overheating and the generation of nonlinear fields. In addition, the compatibility between the temperature control module and the imaging and tracking subsystem is managed by the collision and interference control module. In the imaging and tracking subsystem, the positioning and imaging information of the internal and external imaging subsystems are fused to achieve accurate in vivo magnetic tracking and navigation of the controlled element. A motion control mechanism supports the internal imaging and tracking system to achieve imaging in a large workspace. In one embodiment, a mobile C-arm is used to position the external imaging system. In one embodiment, a six-degree-of-freedom robotic arm is used to control the motion of the external imaging system.

[0089] FIG3 shows several possible magnetic source design embodiments of the present invention. FIG3(a) shows an electromagnetic source design embodiment. The coils are evenly arranged around the built-in sensor module 11 for simple calculation. In one embodiment, ultrasound and a camera are used to sense the controlled element. 9 is the adjacent angle between each coil axis, which determines the number of electromagnetic coils. 10 is a single magnetic coil composed of a soft iron core, copper wire and a cooling system. 16 is the tilt angle between the axis of a single magnetic coil and the central axis. These two angles are designed according to the magnetic field requirements. The adjacent angle determines the number of single magnetic sources and the degree of freedom of magnetic field generation. The tilt angle shape determines the characteristics of magnetic field generation. In one embodiment of the present invention, the posture of a single magnetic source can be configured by a linear or rotary motor. FIG3(c) shows a reconfigurable coil support structure design for a single coil in one embodiment of the present invention. 17 is a linear motor, 19 is a universal ball joint. 18 is a static structure connected to a robot platform, and 20 is a single electromagnetic coil. FIG3(d) shows an embodiment of the present invention that can adjust the posture of a single electromagnet by a rotary motor. 26 and 27 are serial manipulators forming a four-bar linkage. A rotary motor mounted on one of the joints can change the posture of the magnetic source. FIG. 3(e) shows an embodiment of a posture adjustment device of the present invention, which is composed of a linear motor 28, a universal ball joint 29 and a serial manipulator 30. FIG. 3(f) shows that the posture adjustment design in an embodiment of the present invention uses a single linear motor to adjust the posture of a single electromagnetic coil. FIG. 3(g) shows four embodiments of the magnetic core tip design of the present invention. The cylindrical tip design can achieve flat magnetic field generation characteristics, while the cone can concentrate a greater field strength near the tip. The stepped tip design allows a stronger field to be generated in a relatively large area in front. The round head design can generate magnetic field characteristics similar to a dipole model, which is convenient for magnetic field modeling. FIG. 3(h) shows two embodiments of the electromagnetic coil shape design of the present invention. 32 is a stepped coil shape design, which can achieve the generation of a stronger magnetic field with the same amount of copper wire.

[0090] FIG4 shows an embodiment of the temperature control system design. FIG4(a) shows a cross-sectional view of an embodiment of the electromagnetic coil cooling design. 33 is a cooling channel made of a high thermal conductivity material, such as copper. The cooling heat exchange fluid circulates in 33 to remove the excess heat from the surface of the electromagnetic coil. FIG4(b) shows an embodiment of the cooling channel design. Temperature sensors are installed in the soft iron core, inside the copper wire, and at the outlet and inlet of the circulation channel. FIG4(cf) shows four embodiments of the magnetic core cooling system of the present invention. The internal cooling channel of the soft iron core circulates heat exchange fluid like the external cooling channel. Multiple sets of circulation loops increase the cooling efficiency, and the inlet and outlet temperatures are monitored to adjust the circulation speed. The figure shows an embodiment of the channel shape design. Since the cooling channel occupies the volume of the soft iron core and reduces its magnetic field generation capability, the design of the cooling channel should take into account the cooling efficiency and magnetic field generation requirements.

[0091] The present invention includes a method for modeling a magnetic field of an electromagnetic source having a soft iron core having an internal structure. Prior art includes dipole field modeling, finite element method (FEM) modeling, and learning-based modeling techniques. The hybrid modeling method of the present invention is applicable to electromagnetic fields having various shapes and internal structures. The method includes three steps: first, simulating the magnetic field distribution of a CAD magnetic coil model. Second, performing multi-point manual magnetic field distribution measurements in a workspace or an area of ​​interest. Third, calibrating the simulated data with the measured data using a learning-based mapping modeling method. By increasing the number of measurements, the modeling accuracy can be improved.

[0092] FIG. 5 shows an embodiment of the robot platform design of the present invention. The motion of the magnetic source is controlled by the robot structure, which can provide a dexterous posture control for the magnetic source. In one embodiment, as shown in FIG. 5( a ), a serial robot arm design is used to achieve motion control, two serial manipulators 36 and 37 control in-plane motion, and the other two serial manipulators control out-of-plane motion. Although the load tolerance is limited, the serial robot arm can provide more degrees of freedom. In one embodiment, as shown in FIG. 5( b ), the lever structure design of the robot platform can provide sufficient load tolerance to support a larger magnetic source. 40 is a passive serial manipulator supporting a linear drive mechanism 39. 41 is a linear motor that can change the position of the serial manipulator 42. The robot structure can achieve in-plane motion control of heavy loads by controlling two motors. FIG. 5( c ) shows an embodiment of the robot platform structure of the present invention. 43 is a track arranged around the bed, and this design realizes stable translational motion of the robot structure. The robot structure is composed of a rotary motor 47 and a linear motor 48. 46 is an embodiment of the electromagnetic source of the present invention. 45 is an integrated built-in imaging tool. Figure 5(d) shows a design embodiment of the present invention using a moving magnetic source to achieve multi-point magnetic field control. The number of magnetic source groups is determined by the magnetic field generation requirements and space limitations.

[0093] FIG6 shows an embodiment of the built-in tracking system design. In the embodiment shown in FIG6(a), the ultrasound probe is fixed by a micro parallel robot that can control 6 degrees of freedom in the ultrasound imaging plane. In an embodiment shown in FIG6(b), one rotational degree of freedom is controlled by a rotary motor. This design is simpler and can provide 2D plane information of the controlled object. The built-in imaging system will follow the movement of the controlled element and provide effective and efficient positioning.

[0094] FIG7 shows an embodiment of a magnetic isolation shield design 50 and a magnetic field monitoring system design 51. The shield is composed of multiple layers of high and low permeability materials to isolate high and low frequency magnetic fields. Its shape is designed to enclose the magnetic field flux and limit the influence of the magnetic field to the workspace 52. The monitoring module is composed of multiple sensors, including but not limited to magnetic sensors, temperature sensors, and humidity sensors. Based on the additional information about the electromagnetic source provided by the monitoring module, the host computer can estimate the required drive field with higher accuracy.

[0095] The present invention can be better understood by reference to the following experimental details, however, those skilled in the art will readily appreciate that the specific experiments described are for illustrative purposes only and are not meant to limit the invention described herein, which should be defined by the claims set forth subsequently.

[0096] Various references or publications are cited in this application. The entire contents of these references or publications are hereby incorporated by reference into this application to more fully describe the prior art in the field to which the present invention belongs. It should be noted that the transitional term "comprising" is synonymous with "including", "containing" or "characterized by", is inclusive or open-ended, and does not exclude additional, unstated elements or method steps. Example

[0097] FIG8 shows a design example of the present invention, which includes four parts: a mobile magnetic source 56, 57 with 3-DOF motion control, an external fluoroscopy device 55 supported by a C-arm with adjustable position and rotation angle, a built-in ultrasonic tracking probe 59 that provides precise positioning of the controlled object, and a central processing system 53 that can coordinate the entire system to achieve magnetic actuation and controlled object tracking in the body. FIG8(a) shows the arrangement of the subsystems, which enables the magnetic actuation and imaging tools to share the same human-sized workspace. The subsystems are mounted on rails 58, 54 to achieve stable movement around the bed. FIG8(b) shows the design details of the magnetic source of the present invention, including 4 coils and a built-in ultrasonic imaging tool 59.

Claims

1. A device for controlling a magnetic element, comprising: a. A magnetic drive unit, the magnetic drive unit comprising: i. A built-in sensor module; ii. A plurality of magnetic sources, the plurality of magnetic sources being uniformly arranged around the built-in sensing module, each of the plurality of magnetic sources being inclined at an inclined angle and separated from an adjacent magnetic source at an adjacent angle; and iii. an adjustment mechanism connected to each of the plurality of magnetic sources to adjust the tilt angle and the adjacent angle to achieve a desired magnetic field; b. A robot platform, which is used to install the magnetic drive unit and provide dexterous posture control of the magnetic drive unit.

2. The device according to claim 1, characterized in that: The built-in sensing module includes one or more components selected from the following: a camera, a 2D / 3D ultrasonic probe, an X-ray generator, an electrostatic sensor, a magnetic sensor, a fluorescence sensor, an optical transmissometer, a force sensor, a grating sensor, a photoacoustic probe, a laser speckle imaging, an infrared thermal imaging camera, a radio frequency probe or a humidity sensor.

3. The device according to claim 2, characterized in that: The ultrasonic probe is regulated by a position control mechanism, and the position control mechanism is selected from a parallel manipulator or a serial manipulator control.

4. The device according to claim 1, characterized in that: The regulation mechanism comprises a configuration selected from the following: a. Two linear motors (17) and two universal ball joints (19); b. a four-bar linkage consisting of four serially connected manipulators (26, 27); c. a linear motor (28), a universal ball joint (29) and a tandem manipulator (30); and d. A linear motor (31) or a rotary motor.

5. The device according to claim 1, characterized in that: The plurality of magnetic sources include electromagnets or permanent magnets.

6. The device according to claim 5, characterized in that: The electromagnet comprises a soft iron core, copper wire and a temperature control module for controlling the temperature of the soft iron core, wherein the temperature control module comprises: a. a cooling channel having an inlet and an outlet, wherein the cooling channel surrounds the soft iron core or is located within the soft iron core; b. a cooled heat exchange fluid entering and leaving the cooling channel from the inlet and the outlet, respectively; and c. Temperature sensors installed at the inlet, the outlet and embedded in or located within the soft iron core.

7. The device according to claim 6, characterized in that: The soft iron core has a stepped design.

8. The device according to claim 6, characterized in that: The tip of the soft iron core is cylindrical, conical, stepped or circular.

9. The device according to claim 5, characterized in that: The current supplied to the electromagnet is controlled by a current control unit to achieve the required magnetic field. The current control unit includes a bidirectional power supply unit, an H-bridge regulation unit and a microcontroller unit.

10. The device according to claim 1, characterized in that: The magnetic element is selected from one or more of the following: a cabled magnetic robot, a magnetic catheter, a magnetic guidewire, a magnetic needle, a magnetic sleeve, a magnetic soft robot, a magnetic continuous robot, a cable-free magnetic robot, a magnetic spiral swimmer, a magnetic roller, a magnetic clamp, a magnetic surgical tool, a magnetic endoscope or a magnetic capsule endoscope.

11. The device according to claim 1, characterized in that: The device further includes a magnetic isolation shield composed of layers of materials with different magnetic permeabilities.

12. The device according to claim 1, characterized in that: The robot platform includes a configuration for performing dexterous posture control on the magnetic drive unit, the configuration being selected from one or more of the following: a. Two serial manipulators (36, 37) for controlling the movement in the plane, and two serial manipulators (38) for controlling the movement out of the plane; b. a first linear drive mechanism (39) supported by a first serial manipulator (40) and a second serial manipulator (42), wherein the second serial manipulator is connected to a second linear drive mechanism (41); and c. A rotary drive (47) and a linear drive (48).

13. The device according to claim 1, characterized in that: The robotic platform includes a guide rail (43) for stabilizing the translational movement of the device.

14. A system comprising: a. a magnetic element; b. One or more devices according to claim 1; c. a built-in imaging system (2); as well as d. a computer processor; The computer processor is used to execute an algorithm, which cooperates with the one or more devices and the built-in imaging system (2) and includes the following steps: i. receiving posture information of components in the system; ii. calculating the desired trajectory of the one or more devices and the built-in imaging system (2) according to claim 1 according to a user command to operate the magnetic element before the operation; iii. analyzing the real-time position of an object in the field of view of the built-in imaging system during the operation; and iv. Detecting potential collisions using a predictive control strategy based on the real-time position to adjust the desired trajectory.

15. The system according to claim 14, characterized in that: The system further includes a hospital bed having an embedded sensing and tracking module.

16. The system according to claim 14, characterized in that: The built-in imaging system is combined with a mobile C-arm.

17. The system according to claim 14, characterized in that: The magnetic element is selected from a magnetic catheter, an untethered magnetic microrobot or a magnetic capsule endoscope.

18. The system according to claim 14, characterized in that: The plurality of magnetic sources include electromagnets, and current supplied to the electromagnets is controlled by a current control unit to achieve a desired magnetic field. The current control unit includes a bidirectional power supply unit, an H-bridge regulation unit, and a microcontroller unit.

19. The system according to claim 14, characterized in that: The algorithm further includes a hierarchical control method to coordinate the movement of the system and the generation of the magnetic field, the hierarchical control method including a first level to control safety distance and collision prevention; and a second level to control magnetic field generation and imaging field of view.

20. The system according to claim 14, characterized in that: The system further includes a module for a user to intervene in and override the control of the system over the algorithm.

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