Magnetic resonance imaging safety maneuvering system: fluid-based bellows actuator, sensor, mechanism, and system

Abstract

A magnetic resonance imaging (MRI) safe steering system is provided. In one embodiment, the system includes: a) a guide mechanism; and b) one or more fluid driven bellows actuators. In one embodiment, the guide mechanism is a surgical intervention tool and the one or more bellows actuators are linear bellows actuators; the system further includes: a) a first gripper for gripping the surgical intervention tool at a first position; b) a second gripper for gripping the surgical intervention tool at a second position, the second position being separated from the first position by one of the one or more bellows actuators; the first gripper and the second gripper each include a diaphragm that expands under fluid pressure to grip the surgical intervention tool.

Description

Technical Field

[0001] This invention relates to actuators, sensors, mechanisms, and systems for safe magnetic resonance imaging (MR), and particularly to safe control techniques for MR imaging used in medical robots and minimally invasive surgery. Background Technology

[0002] Magnetic resonance imaging (MRI) can achieve high-resolution anatomical imaging, high soft tissue contrast, and thermal imaging and monitoring, and can provide excellent imaging results in the diagnosis and treatment of spinal, joint and brain-related surgeries. At present, a variety of actuators, sensors and robotic systems have been developed to perform surgical operations under MRI guidance, and achieve high motion accuracy and high placement accuracy in tool positioning, posture adjustment and insertion into the target body part. However, according to the relevant standards set by the American Society for Testing and Materials (ASTM) [1], items used in MRI scanning chambers with high magnetic field strength and rapid switching magnetic field gradient characteristics must be MR safe (i.e., only non-conductive, non-metallic and non-magnetic materials are involved), or at least MR conditionally safe (i.e., materials that do not have known hazards under specific magnetic resonance environment and specified use conditions). This requirement limits the application of many traditional actuators, sensors and mechanisms in robotic systems in MRI environments. In addition, there are several other challenges in developing and adopting mechanisms and robotic systems that can be used in MRI scanning environments, including the limited space of MRI scanning aperture and the complex operation procedures required to move patients into and out of the MRI aperture before or during surgery.

[0003] Various MRI-guided robotic systems have been developed for guiding needles or surgical tools in surgeries of the liver, breast, prostate, and brain, including positioning robots with remote center of motion (RCM) constraints and stereotactic targeting capabilities. These robotic systems typically employ ultrasonic and piezoelectric motors as actuators, arranged in different configurations [2–8]. Although these motors are generally considered MR conditionally safe, they can still generate electromagnetic interference when placed near the MRI aperture, resulting in a non-negligible decrease in the signal-to-noise ratio (SNR) of MR images.

[0004] Researchers have also explored intrinsically MR-safe robotic arms for surgical instruments by employing hydraulic and / or pneumatic actuators. For example, researchers at the University of Twente have proposed an MR-safe pneumatic stepper actuator [9–12]. Stoianovici et al. developed a needle-guided robot using a pneumatic stepper motor

[13] . He et al. proposed a hydraulically based RCM-constrained soft robot with a latching locking mechanism

[19] . Although the above fluid-based actuators are MR-safe, other limitations still exist that affect robot performance. Due to the compressibility of air, pneumatic actuators are challenging to achieve high responsiveness and high control accuracy, especially over long transmission distances

[14] . Most existing hydraulic drive systems are based on piston-cylinder structures

[15] or rolling diaphragm structures [16–20], which suffer from fluid leakage and short output stroke, respectively. In addition, discontinuous motion, insufficient output torque, and large size of the master controller are also limitations of existing MR-safe actuators.

[0005] In recent years, various MR-safe needle robots with needle actuators have been proposed to enable non-manual or "electric" needle placement, thus enabling percutaneous surgery under continuous magnetic resonance imaging conditions. Frishman et al. proposed a seven-DOF robotic arm combined with a pneumatically driven needle actuator with force feedback

[21] . However, the system uses a serial robotic arm design and does not have mechanical RCM constraints, so it is not suitable for needle-based spinal surgery with extremely high precision requirements. In addition, hydraulic needle actuators based on piston-cylinder structure

[15] and rolling diaphragm structure

[22] have been proposed recently, but both have the problem of relatively short needle translation stroke

[22] . Most other existing needle actuators for MRI and other medical image-guided applications are driven by ultrasonic motors [6],

[23] ,

[24] . Given that the needle actuator needs to be driven under continuous magnetic resonance imaging conditions and is usually placed near the region of interest (ROI), using MR-safe actuators as needle actuators is a more ideal choice and will be more conducive to obtaining optimal imaging quality.

[0006] Existing MR safety robotic arms are usually driven by hydraulic or pneumatic methods, but they still face a number of problems, including short output stroke, insufficient structural rigidity, fluid leakage, low transmission efficiency and complex mechanism

[25] ,

[11] . In view of the above limitations, this invention proposes a series of MR safety enabling technologies suitable for robotic applications in medical imaging environments, especially suitable for MRI scanning chambers, such as: circular / arc bellows actuators and their remote motion center (RCM) mechanisms, linear bellows needle drivers, connected bellows systems for master-slave drive architectures, diaphragm-based fluid-driven locking mechanisms, and fiber optic-based sensor and origin position calibration mechanisms. It should be understood that the above new technologies are also applicable to other medical imaging environments, including but not limited to computed tomography (CT), in which metallic materials located in the region of interest can also affect image quality. Summary of the Invention

[0007] This invention provides a safe control system for magnetic resonance imaging (MRI). In one embodiment, the system includes: a) a guiding mechanism; and b) one or more fluid-driven bellows actuators.

[0008] In one embodiment, the guiding mechanism is a surgical interventional tool, and the one or more bellows actuators are linear bellows actuators; the system further includes: a) a first clamp for clamping the surgical interventional tool in a first position; b) a second clamp for clamping the surgical interventional tool in a second position, the second position being separated from the first position by one of the one or more bellows actuators; both the first clamp and the second clamp include a diaphragm that expands under fluid pressure to clamp the surgical interventional tool. Attached Figure Description

[0009] The embodiments of the present invention will be illustrated with reference to system diagrams and module diagrams. Further embodiments will be described using user operation flowcharts and user interface wireframes.

[0010] Figure 1A This diagram shows a linear bellows actuator.

[0011] Figure 1B A detailed schematic diagram of an antagonistic linear bellows needle actuator for tool control is shown.

[0012] Figure 1C The tool is inserted into the working process in a front view, with clamp A and clamp B sequentially performing clamping, moving, and releasing actions.

[0013] Figure 1DThe Ansys simulation results show the expansion of clamps A and B under a pressure of 50 kPa.

[0014] Figure 2A A detailed schematic diagram of a single linear bellows microneedle actuator used for tool manipulation is shown.

[0015] Figure 2B This demonstrates two different operating states for each gripper.

[0016] Figure 3 The system demonstrates a position sensing and feedback system for a micro needle actuator.

[0017] Figure 4A A schematic diagram showing a circular / arc bellows actuator; Figure 4B Showcase the slider-rail system that mates with each pair of antagonistic circular / arc bellows actuators.

[0018] Figure 5A The simulation workspace of a remote motion center (RCM) mechanism is shown, consisting of two stacked circular / arc bellows actuator guidance systems.

[0019] Figure 5B The workspace is shown under pitch and yaw degrees of freedom.

[0020] Figure 6 An exploded view of the robotic arm system is shown, including an RCM mechanism consisting of guide system 1 and guide system 2, and a needle driver.

[0021] Figure 7A A schematic diagram showing the use of a connected bellows as the master-slave drive unit is presented.

[0022] Figure 7B The detailed structure of the main controller is shown, which is part of the connected bellows system.

[0023] Figure 8A A CAD model of a silicone diaphragm and its working principle are displayed.

[0024] Figure 8B The manufacturing process of silicone diaphragms is demonstrated.

[0025] Figure 8C This demonstrates the displacement-pressure relationship of the silicone diaphragm.

[0026] Figure 9A Demonstrates a fiber-optic relative AB phase encoder.

[0027] Figure 9B The origin point positioning mechanism is displayed. Detailed Implementation

[0028] Currently, several magnetic resonance imaging (MRI) safe actuators, sensors, mechanisms, and systems have been developed for robotic applications in medical imaging environments, such as MRI, which impose strict limitations on the selection of materials to avoid adverse effects on equipment operation, imaging quality, and, most importantly, safety. This invention proposes several technical solutions, including: 1) an MRI-safe fluid-driven circular / arc bellows actuator for controlling a robotic system in medical imaging environments including but not limited to MRI and computed tomography (CT); 2) an MRI-safe remote motion center (RCM) mechanism comprising two stacked circular / arc bellows actuators, suitable for medical imaging environments including but not limited to MRI and CT; 3) an MRI-safe antagonistic bellows fluid-driven needle actuator equipped with a diaphragm-based gripper for performing insertion, retraction, and rotation manipulations on tools including but not limited to needles, ablation probes, and brachytherapy devices; 4) an MRI-safe single bellows fluid-driven needle actuator equipped with a diaphragm-based gripper for performing insertion, retraction, and rotation manipulations on tools including but not limited to needles, ablation probes, and brachytherapy devices; 5) A connected bellows system, including a master bellows and a slave bellows connected by a transmission channel, for controlling a robotic system in medical imaging environments including but not limited to MRI and CT; 6) an MRI-safe diaphragm-based fluid-driven locking mechanism for integration into a robotic system in medical imaging environments including but not limited to MRI and CT; 7) an MRI-safe fiber-optic sensing system integrated with a bellows actuator for angular and linear displacement detection, origin calibration, and closed-loop control in medical imaging environments including but not limited to MRI and CT.

[0029] Many percutaneous minimally invasive surgeries require precise targeting of tools such as needles and therapeutic probes under image guidance. Currently, several MRI-safe actuators, sensors, mechanisms, and systems have been developed as enabling technologies in medical robotic systems. These technologies enable high-precision surgical procedures in medical imaging environments, including but not limited to MRI, which impose strict limitations on material selection to avoid adverse effects on equipment operation, image quality, and, most importantly, safety. This invention proposes several technical solutions, including: 1) a fluid-driven bellows actuator made entirely of MR-safe materials, with geometric configurations including linear / straight and circular / arc shapes; 2) an antagonistic linear bellows-driven needle actuator for tool manipulation, including translation and rotation; 3) a single bellows-driven micro-needle actuator for tool manipulation, including translation and rotation; 4) an antagonistic arc-shaped bellows-driven rotary joint, which forms a remote center of motion (RCM) mechanism through stacking; 5) a robotic arm including an RCM mechanism and a needle actuator, both driven by fluid-driven bellows actuators; 6) a connected bellows system in a master-slave architecture, including a master bellows and a slave bellows connected through a transmission channel; 7) a diaphragm-based fluid-driven locking mechanism for integration into MRI-compatible robotic systems; and 8) a fiber-optic-based sensing system integrated with bellows actuators for angular and linear displacement detection, origin calibration, and control in an MRI environment. The aforementioned MRI-safe actuators, sensors, mechanisms, and systems possess unique advantages such as excellent compactness, large stroke, high structural rigidity, and large output force, significantly advancing the current technological level of using MRI-safe robots in confined medical imaging environments such as MRI.

[0030] In one embodiment, the present invention provides an MRI-safe fluid-driven circular / arc bellows actuator for controlling robotic systems in medical imaging environments including but not limited to MRI and computed tomography (CT).

[0031] In one embodiment, the present invention provides an MRI-safe remote motion center (RCM) mechanism comprising two stacked circular / arc bellows actuators, suitable for medical imaging environments including but not limited to MRI and CT.

[0032] In one embodiment, the present invention provides an MRI-safe antagonistic bellows fluid-driven needle actuator equipped with a diaphragm-based gripper for performing manipulation actions such as insertion, retraction, and rotation on tools including but not limited to needles, ablation probes, and brachytherapy devices.

[0033] In one embodiment, the present invention provides an MRI-safe single-bellows fluid-driven needle actuator equipped with a diaphragm-based gripper for performing manipulation actions such as insertion, retraction, and rotation on tools including but not limited to needles, ablation probes, and brachytherapy devices.

[0034] In one embodiment, the present invention provides a connected bellows system including a master bellows and a slave bellows connected by a transmission channel for controlling a robotic system in medical imaging environments including but not limited to MRI and CT.

[0035] In one embodiment, the present invention provides an MRI-safe diaphragm-based fluid-driven locking mechanism for integration into robotic systems in medical imaging environments including but not limited to MRI and CT.

[0036] In one embodiment, the present invention provides an MRI-safe fiber-optic sensing system integrated with a bellows actuator for angular and linear displacement detection, origin position calibration, and closed-loop control in medical imaging environments including but not limited to MRI and CT.

[0037] This invention provides a safe control system for magnetic resonance imaging (MRI). In one embodiment, the system includes: a) a guiding mechanism; and b) one or more fluid-driven bellows actuators.

[0038] In one embodiment, the guiding mechanism is a surgical interventional tool, and the one or more bellows actuators are linear bellows actuators; the system further includes: a) a first clamp for clamping the surgical interventional tool in a first position; b) a second clamp for clamping the surgical interventional tool in a second position, the second position being separated from the first position by one of the one or more bellows actuators; both the first clamp and the second clamp include a diaphragm that expands under fluid pressure to clamp the surgical interventional tool.

[0039] In one embodiment, the surgical interventional tool includes a needle, an ablation probe, or a brachytherapy device.

[0040] In one embodiment, the system is used to manipulate the surgical interventional tool to perform one or more movements.

[0041] In one embodiment, the one or more movements include translation or rotation achieved through a "clamp-move-release" work sequence.

[0042] In one embodiment, the guide mechanism and the one or more bellows actuators form one or more arc drive systems; in each of the arc drive systems: the guide mechanism includes one or more sliders that move along one or more guide rails; the one or more bellows actuators include pairs of antagonistic arc bellows actuators; each pair of antagonistic arc bellows actuators is respectively connected to the same one of the one or more sliders.

[0043] In one embodiment, the system further includes a guide housing.

[0044] In one embodiment, the one or more arc-shaped drive systems include a first arc-shaped drive system and a second arc-shaped drive system; the first arc-shaped drive system and the second arc-shaped drive system are stacked to form a remote motion center mechanism.

[0045] In one embodiment, the system further includes a fluid-driven diaphragm that expands under fluid pressure to form a locking mechanism.

[0046] In one embodiment, the system further includes a transmission channel connecting a slave actuator and a master actuator among the one or more bellows actuators to form a connected bellows system under a master-slave control architecture.

[0047] In one embodiment, the system further includes an optical fiber-based incremental AB phase encoder.

[0048] In one embodiment, the system further includes an optical fiber-based origin position calibration mechanism.

[0049] The present invention can be better understood through the following embodiments. However, those skilled in the art should understand that the specific embodiments are for illustrative purposes only and do not constitute a limitation on the present invention. The scope of protection of the present invention is defined by the appended claims. Several documents or publications are referenced in this application. Their entire contents are incorporated herein by reference to more fully illustrate the prior art to which the present invention pertains. It should be noted that the transitional term "comprising" used herein is equivalent to "including," "containing," or "characterized by," and is an open or open term, not excluding the presence of other elements or method steps not explicitly listed.

[0050] Example 1

[0051] Figure 1A This demonstrates a linear bellows actuator expanding under fluid pressure, with quick-connect fittings at both its head and tail ends. 1-1: Linear Bellows Actuator. Figure 1BThe components of an antagonistic linear bellows-driven needle actuator are shown. 1-2: Holder B; 1-3: Holder A; 1-4: Silicone diaphragm; 1-5: Inlet; 1-6: Grating disk; 1-7: Bellows; 1-8: Encoder; 1-9: Guide rail; 1-10: Needle. The needle actuator, equipped with a silicone diaphragm-based fluid-driven holder and a fluid-driven bellows, is capable of manipulating surgical instruments to perform various movements. Figure 1C The demonstration shows how the needle driver inserts the tool into the target location in a worm-like motion pattern through a sequence of actions: clamping by the gripper, movement of the bellows, and release of the gripper. Figure 1D This demonstrates the Ansys deformation simulation results of grippers A and B expanding under fluid pressure to achieve tool clamping.

[0052] like Figure 1A The bellows shown can expand and contract under fluid pressure. In the needle actuator, the bellows are arranged in an antagonistic configuration, as shown... Figure 1B As shown, two bellows are installed on both sides of the gripper A to apply force to the gripper, thereby applying force to the tool to achieve its translational movement. It should be understood that the tool described herein may include instruments requiring similar manipulation, such as needles, ablation probes, or brachytherapy devices.

[0053] like Figure 1B As shown, the needle actuator consists of two grippers (A and B), two pairs of antagonistic bellows positioned on either side of the tool, an optical fiber, a grating disk, a linear bearing, a ceramic guide rod, and a housing. Each gripper includes a silicone diaphragm that expands to grip the tool when fluid pressure is applied and returns to its natural shape when the fluid pressure is released, thereby releasing the tool.

[0054] The translational motion of the needle actuator simulates the gradual insertion of a tool by hand. Specifically, the needle actuator uses a "clamp-move-release" sequence to achieve translational motion. The tool insertion process is as follows: Figure 1C As shown, the process mainly includes the following two steps: i) Clamp A grips the tool at its lower end, while clamp B releases its grip, subsequently driving the bellows to push clamp A and the tool downwards, thus achieving tool insertion; ii) Clamp A releases its grip, while clamp B grips the tool at its upper end, subsequently driving the bellows back to its original position while the tool remains stationary. These steps constitute a single cycle of driving the tool downwards (each cycle involves a displacement of approximately 20 mm), and this cycle can be repeated to achieve long-stroke tool insertion. It should be noted that clamp A moves continuously, while clamp B remains stationary throughout. Figure 1DThis demonstrates the effectiveness of the silicone diaphragm-based gripper, which undergoes significant deformation under 50 kPa pressure, thereby establishing a firm contact with the tool and achieving reliable clamping. This is a compact and efficient MRI safety needle actuator design that achieves long-stroke tool insertion while minimizing the size of the actuator module.

[0055] Example 2

[0056] Figure 2A This demonstrates a highly compact miniature needle actuator driven by a single fluid-driven linear bellows. 2-1: Housing; 2-2: Needle; 2-3: Needle guide; 2-4: Bellows; 2-5: Holder A; 2-6: Grating disk; 2-7: Linear bearing; 2-8: Guide rod; 2-9: Holder B; 2-10: Bellows connector; 2-11: Tubing connector; 2-12: O-ring. Figure 2B The structural design of each clamp in the needle driver and its two different working states are shown.

[0057] Figure 2A This paper demonstrates the design of a microneedle actuator driven by a single bellows. Positive pressure controls the expansion or elongation of the bellows, while negative pressure controls its retraction. The microneedle actuator employs a "grip-move-release" sequence for translational motion. Gripper A expands under fluid pressure to grip the tool, while gripper B releases the grip. Subsequently, the bellows expands under positive fluid pressure, moving the tool downwards. Next, gripper B expands to grip the tool again, while gripper A releases the grip. Finally, the bellows retracts under negative fluid pressure, returning gripper A to its original position. This process can be repeated to drive the tool into the target location on the human body. Quick-connect fittings are provided at each fluid connection point between the bellows and the gripper, and all connections are sealed with O-rings.

[0058] Example 3

[0059] Figure 3This document demonstrates a position sensing and feedback system for a miniature needle actuator, comprising an incremental AB phase encoder and an origin position calibration mechanism. 3-1: Laser source; 3-2: Photodiode; 3-3: Fixed calibration fiber; 3-4: Moving calibration fiber; 3-5: A-phase fiber; 3-6: B-phase fiber. The AB phase encoder includes two transmitting fibers, two receiving fibers, and a grating disk, generating A-phase and B-phase signals via a single laser source. The fiber has an inner diameter of 0.5 mm and an outer diameter of 1 mm. The origin position calibration mechanism includes a transmitting fiber located on a guide rail and a receiving fiber mounted on a slider. The receiving fiber receives the corresponding signal indicating the origin position of each axis only when the transmitting and receiving ends are aligned, thus achieving closed-loop control of the needle actuator's origin homing capability.

[0060] Example 4

[0061] Figure 4A Demonstrates the expansion of a circular / arc-shaped bellows actuator under fluid pressure, with quick-connect fittings at both the head and tail ends. 4-1: Circular Bellows Actuator. Figure 4B Showing the slider and guide rail that mate with each pair of antagonistic circular / arc bellows. 4-2: Slider; 4-3: Guide rail; 4-4: 3D printed shell.

[0062] like Figure 4A As shown, the circular / arc-shaped bellows actuator can expand under fluid pressure, and due to its own flexibility, it can be guided by a slider and guide rail (such as...). Figure 4B With the assistance of (as shown), the slider can deform or move along a specific circular or arc-shaped trajectory. A pair of circular / arc-shaped bellows actuators are mounted on each side of the slider, forming an antagonistic structure. When fluid pressure is applied, these actuators deform to push the slider along the arc-shaped trajectory. Each guide rail includes an arc-shaped groove and a guide housing, while each slider is equipped with a ceramic bearing and a hydraulically driven locking mechanism. The bearings limit the slider's displacement in the horizontal and vertical directions, ensuring smooth sliding between the slider and the guide rail.

[0063] Example 5

[0064] Figure 5A This paper presents a simulated workspace for a remote motion center (RCM) mechanism, which includes two stacked circular / arc bellows actuator guide systems. Figure 5B The workspace is shown under two degrees of freedom of motion of the RCM, namely pitch freedom and yaw freedom.

[0065] The Remote Motion Center (RCM) mechanism comprises two stacked circular / arc-shaped bellows actuator guidance systems to achieve the pitch and yaw rotation degrees of freedom for RCM motion. As shown in Figure 5, the central intersection of the two arc-shaped trajectories is the RCM point, located slightly below the overall robot structure, thus coinciding with the tool puncture point on the patient's skin. Using fluid-driven circular / arc-shaped bellows as local actuators moving along arc-shaped trajectories within the RCM mechanism helps generate a large output force to support the motion of the cascaded mechanical structures. More importantly, this design provides a highly compact RCM mechanism while achieving a large range of rotational angles in two decoupled degrees of freedom. These characteristics make it highly suitable for various percutaneous surgical procedures performed in closed environments with intraoperative imaging modes such as MRI and CT.

[0066] Example 6

[0067] Figure 6 An exploded view of the robotic arm is shown. The robotic arm includes a needle actuator driven by a linear bellows actuator and controlled by a remote motion center (RCM) mechanism. The RCM mechanism consists of two arc-shaped guide systems, using circular / arc-shaped bellows as actuators. 6-1: Guide system 1; 6-2: Guide system 2; 6-3: Guide rail; 6-4: Bellows; 6-5: Rod; 6-6: Silicone diaphragm; 6-7: Bearing; 6-8: Arc-shaped housing; 6-9: Needle actuator; 6-10: Slider; 6-11: MR coil mounting slot.

[0068] By combining a linear bellows-driven needle actuator with a circular / arc bellows-driven RCM mechanism, a three-DOF MR safety robotic arm with mechanical RCM constraints and an electric needle actuator is constructed, such as... Figure 6 As shown in Figure A, the robotic arm is entirely constructed of MR safety materials and employs bellows-based fluid actuators in all its degrees of freedom. Guide system 1 provides pitch freedom, while guide system 2 provides yaw freedom. Guide system 1 has two guide rails, each corresponding to one of two sets of antagonistic circular / arc bellows actuators, to support the weight of guide system 2 and the needle driver. Guide system 2 has only one guide rail, providing one pair of antagonistic circular / arc bellows actuators. The antagonistic bellows actuators in guide system 2 are directly connected to the needle driver.

[0069] Example 7

[0070] Figure 7A Demonstrates a connected bellows system as a master-slave drive unit. 7-1: Robot slider; 7-2: Nut; 7-3: Drive slider; 7-4: Ball screw; 7-5: Motor. Figure 7B The main controller is shown, which drives the robotic arm via a continuous bellows. Wherein: 7-6: bellows; 7-7: water outlet; 7-8: guide rail.

[0071] like Figure 7A As shown, the robotic arm of this invention adopts a master-slave drive mode and uses a fluid such as pressurized water as the transmission medium. Due to the good flexibility and large stroke-to-volume ratio of the bellows, it is used as a local fluid actuator for the slave robot to drive the movement of the sliders of each degree of freedom. Compared with rolling diaphragms, bellows can achieve significantly greater displacement without integrating additional mechanisms, providing a more compact solution. This invention introduces the concept of connected bellows in a master-slave drive architecture for the first time, used to drive the degrees of freedom of the two RCMs and the tool translation degree of freedom. As shown in Figure 7, the drive slider is rigidly connected to a nut, which cooperates with an electric ball screw. Therefore, the drive ball screw can directly drive the drive slider, thereby applying a push-pull action to the antagonistic bellows at the master control end. Each bellows on the slave robot is directly connected to the corresponding bellows in the master controller through a transmission channel, such as a fluid-filled pipe, thus forming a pair of connected bellows, realizing the function of transmitting force from the master controller to the slave robot. The RCM joints of the driven robot employ circular / arc-shaped bellows, which are connected to linear bellows in the master controller. During translational motion, the interconnected bellows system of the needle actuator includes both the linear bellows in the needle actuator and the linear bellows in the master controller. Compared to traditional hydraulic pumps, bellows have a larger stroke-to-length ratio, allowing for a more compact overall structure of the master controller, supporting a larger fluid volume transfer while occupying less space. Furthermore, the interconnected bellows system applied in the master-slave drive architecture creates a closed drive environment, significantly reducing the fluid leakage risk commonly found in piston-cylinder based master controllers.

[0072] Example 8

[0073] Figure 8A Demonstrates the silicone diaphragm in the locking mechanism and its working principle for locking robots. 8-1: Water inlet. Figure 8B This demonstrates the process of manufacturing a silicone diaphragm using silicone molding. 8-2: Mold 1; 8-3: Mold 2; 8-4: Silicone diaphragm. Figure 8C The pressure-displacement relationship curves of the silicone diaphragm in the experiment and the corresponding simulation results are shown.

[0074] like Figure 8AAs shown, a silicone diaphragm is fixedly connected to the 3D-printed component in the locking mechanism, making the overall shape resemble a box-like structure with an elliptical top layer. The top layer expands under fluid pressure, thereby increasing the friction between the guide rail and the slider, achieving the locking effect. Figure 8B As shown, the diaphragm is prepared by a silicone molding process, in which liquid silicone is injected into the space between two 3D printed molds (i.e., mold 1 and mold 2). Figure 8C The pressure-displacement curves of the silicone diaphragm in experiments and the corresponding simulation results are shown. Because the diaphragm is positioned approximately 1 mm above the guide rail, a gentle contact can be formed between the diaphragm and the guide rail at a working pressure of 10 kPa. During the locking operation, the working pressure is increased to 40 kPa to ensure reliable locking performance.

[0075] Example 9

[0076] Figure 9A This demonstrates the components of a fiber-optic incremental encoder. Figure 9B The origin position calibration mechanisms are shown for the pitch and yaw degrees of freedom, respectively. When the transmitter and receiver are aligned, the robot is at its origin position.

[0077] This invention develops an incremental encoder based on optical fiber, capable of providing real-time position sensing and feedback on each motion axis, thereby achieving closed-loop control of each bellows actuator. For example... Figure 9A As shown, the encoder includes two transmitting optical fibers, two receiving optical fibers, and a grating disk, generating A-phase and B-phase signals through a single laser source. 9-1: Photodiode; 9-2: Encoder; 9-3: Grating disk; 9-4: Laser source. The inner diameter of the optical fiber is 0.5 mm, and the outer diameter is 1 mm. Signals of different phases propagate between the transmitting and receiving optical fibers through an acrylic grating disk with a spacing of 0.5 mm. The spacing is determined experimentally based on processing precision, light loss during propagation, and the sensitivity of the photodiode. The grating disk is positioned on the side of the guide rail away from the rotation axis; this position has a longer arc length, providing higher motion resolution. Figure 9B As shown, this invention also develops an origin position calibration mechanism to provide accurate origin positioning capability for two RCM axes. 9-5: Sliding receiver; 9-6: Fixed transmitter. The origin position calibration mechanism includes a transmitting optical fiber disposed in the middle of the guide rail of each RCM axis, and a receiving optical fiber mounted on the slider of each axis. The receiving optical fiber receives the corresponding signal only when the transmitter and receiver are aligned, thereby indicating the origin position of each axis.

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Claims

1. A magnetic resonance imaging (MRI) safety control system, characterized in that: The system includes: a. a guiding mechanism; and b. One or more fluid-driven bellows actuators.

2. The MRI safety control system according to claim 1, characterized in that: The guiding mechanism is a surgical interventional tool, and the one or more bellows actuators are linear bellows actuators; the system further includes: a. A first clamp for clamping the surgical interventional tool in a first position; b. A second clamp for clamping the surgical interventional tool in a second position, the second position being spaced from the first position by one of the one or more bellows actuators; Both the first and second grippers include a diaphragm that expands under fluid pressure to grip the surgical interventional tool.

3. The MRI safety control system according to claim 2, characterized in that: The surgical interventional tools include needles, ablation probes, or brachytherapy devices.

4. The MRI safety control system according to claim 2, characterized in that: The system is used to manipulate the surgical interventional tool to perform one or more movements.

5. The MRI safety control system according to claim 4, characterized in that: The one or more movements include translation or rotation achieved through a "clamp-move-release" work sequence.

6. The MRI safety control system according to claim 1, characterized in that: The guiding mechanism and the one or more bellows actuators form one or more arc-shaped drive systems; in each of the arc-shaped drive systems: the guiding mechanism includes one or more sliders that move along one or more guide rails; the one or more bellows actuators include pairs of antagonistic arc-shaped bellows actuators; each pair of antagonistic arc-shaped bellows actuators is respectively connected to the same one of the one or more sliders.

7. The MRI safety control system according to claim 6, characterized in that: The system further includes a guide housing.

8. The MRI safety control system according to claim 6, characterized in that: The one or more arc-shaped drive systems include a first arc-shaped drive system and a second arc-shaped drive system; the first arc-shaped drive system and the second arc-shaped drive system are stacked to form a remote motion center mechanism.

9. The MRI safety control system according to claim 6, characterized in that: The system further includes a fluid-driven diaphragm that expands under fluid pressure to form a locking mechanism.

10. The MRI safety control system according to claim 1, characterized in that: The system further includes a transmission channel connecting a slave actuator and a master actuator among the one or more bellows actuators, forming a connected bellows system under a master-slave control architecture.

11. The MRI safety control system according to claim 1, characterized in that: The system further includes an optical fiber-based incremental AB phase encoder.

12. The MRI safety control system according to claim 1, characterized in that: The system further includes an origin position calibration mechanism based on optical fiber.

Images