Vertical farming, a sustainable key for urban agriculture, has garnered attention for its land use optimization and enhanced food production capabilities. The adoption of automation in vertical farming is a pivotal response to labor shortages, addressing the need for increased efficiency, particularly in labor-intensive tasks like harvesting. Although soft robotic grippers offer a significant promise for delicately handling fragile objects, the absence of sensors has hindered their full potential to execute precise and secure grasping. To address this challenge, we present a new solution: a detachable Fiber Bragg Grating-based flexible contact force sensor to capture gripper-vegetable interactions. The sensing module was 3D printed using soft material, and the FBG fiber was attached to the module using epoxy. From evaluation tests, this lightweight sensor demonstrated a wide measurement range of up to 9.87 N, with a high sensitivity of 141.7 pm/N, good repeatability, and a hysteresis of 7.96%. Compared to commercial load cells, our sensor achieves a small measurement RMSE of 0.41 N and a percentage error of 4.15%. The sensor was integrated into two robotic 3D-printed soft grippers to enable real-time monitoring of dynamic contact force during vegetable harvesting in vertical farming scenarios. By reflecting contact status, this sensor provides a promising glimpse into the future of agricultural automation, enhancing operational efficiency and strengthening situation awareness and decision-making capabilities in vertical farms. Beyond agriculture, the versatility of this sensor extends to application in areas such as warehousing, logistics, and the food and beverage industry.

Many teleoperation tasks require three or more tools working together, which need the cooperation of multiple operators. The effectiveness of such schemes may be limited by communication issues between individuals. Trimanipulation by a single operator using an artificial third arm controlled together with their natural arms may address this issue. Foot-controlled interfaces have previously shown the capability to be used for the continuous control of robot arms. However, the use of such interfaces for controlling a supernumerary robotic limb in coordination with the natural limbs is not well understood. In this paper, a teleoperation task imitating physically-coupled hands in a virtual reality scene was conducted with 14 subjects to evaluate human performance during trimanipulation. The participants were required to move three limbs together in a coordinated way mimicking three arms holding a shared physical object. It was found that after a short practice session, three-hand trimanipulation with a single subject’s hands and foot was still slower than dyad operation. However, they displayed similar performance in their success rate and higher motion efficiency than two people cooperating.

Accurate motion control of surgical robots is critical for the efficiency and safety of both state-of-the-art teleoperated robotic surgery and the ultimate autonomous robotic surgery. However, fine motion control for a flexible endoscopic surgical robot is highly challenging because of the shape-dependent and speed-dependent motion hysteresis of tendon-sheath mechanisms (TSMs) in the long, tortuous, and dynamically shape-changing robot body. Aiming to achieve precise closed-loop motion control, we propose a small and flexible sensor to directly sense the large and sharp rotations of the articulated joints of a flexible endoscopic surgical robot. The sensor-a Fiber Bragg Grating (FBG) eccentrically embedded in a thin and flexible epoxy substrate-can be significantly bent with a large bending angle range of [-62.9°, 75.5°] and small bending radius of 6.9 mm. Mounted in-between the two pivot-connected links of a joint, the sensor will bend once the joint is actuated, resulting in the wavelength shift of the FBG. In this study, the relationship between the wavelength shift and the rotation angle of the joint was theoretically modeled and then experimentally verified before and after the installation of the sensor in a robotic endoscopic grasper. The sensor, with the calibrated model, can track the rotation of the robotic joint with an RMSE of 3.34°. This small and flexible sensor has good repeatability, high sensitivity (around 147.5 pm/degree), and low hysteresis (7.72%). It is suitable for surgical robots and manipulators whose articulated joints have a large rotation angle and small bending radius.

Perforations in flexible endoscopy are life-threatening. Defect closure or suturing in flexible endoscopy has long been a critical challenge due to the confined space of the access routes and surgical sites, high dexterity and force demands of suturing tasks, as well as critical size and strength requirements of wound closure. This paper introduces a novel robotic suturing system for flexible endoscopic surgery. This system features a flexible, through-the-scope, five-degree-of-freedom robotic suturing instrument. This instrument allows the surgeon to endoscopically manipulate a needle via a master console to create running stitches and knots in flexible endoscopy, which is not possible with existing devices. Successful ex-vivo trials were conducted inside porcine colons to show how surgical stitches and knots can be endoscopically created and secured in a completely new way. This new technology will change the way how surgeons close defects or perforations in flexible endoscopic surgery.

When performing some surgical tasks inside colon with NOTES technology, colon tissue could block the task space and occlude the endoscopic vision. In order to solve this problem, we developed a pneumatically driven deployable and undeployable structure which can distend collapsing tissue and can be delivered through a 4.5 mm endoscopic channel. The structure is designed to be flexible enough to pass through colon's tortuous pathway. Also, it is designed to hold its shape without continually applying air pressure after deployment. This allows to make use of an endoscopic channel for the other surgical instruments. Besides, due to the compliant nature of the device, it is safe to deploy inside a smaller space than its maximum deployable size. The functionality of the device was verified with an in-vitro experiment. The structure was successfully deployed inside a pig's colon with an inner diameter of 60 mm by applying 3.5 bars of air pressure and created a sufficient task space for surgical operations.

Accurate haptic feedback is a critical challenge for surgical robots, especially for flexible endoscopic surgical robots whose transmission systems are Tendon-Sheath Mechanisms (TSMs) with highly nonlinear friction profiles and force hysteresis. For distal end haptic sensing of TSMs, this paper, for the first time, proposes to measure the compression force on the sheath at the distal end so that the tension force on the tendon, which equals the compression force on the sheath, can be obtained. A new force sensor, i.e., a nitinol tube attached with an optical Fiber Bragg Grating (FBG) fiber, is proposed to measure the compression force on the sheath. This sensor, with similar diameter and configuration (hollow) as the sheath, can be compactly integrated with TSMs and surgical end-effectors. In this paper, mechanics analysis and verification tests are presented to reveal the relationship between the tension force on the tendon and the compression force on the sheath. The proposed force sensor was calibrated in tests with a sensitivity of 24.28 pm/N and integrated with a tendon-sheath driven grasper to demonstrate the effectiveness of the proposed approach and sensor. The proposed approach and sensor can also be applied for a variety of TSMs-driven systems, such as robotic fingers/hands, wearable devices, and rehabilitation devices.

Variable stiffness for robotics is attracting increasing attention from researchers in the field of surgical robots. A surgical robot that can access the human colon or stomach via natural orifices must be flexible enough to pass through tortuous paths and to work in a confined space. Meanwhile, the robot must also be stiff enough to ensure pushability and to hold high payloads during the surgery. Thus, surgical robots with variable stiffness are desirable. This paper presents a new design concept for variable stiffness manipulators using a thermoplastic material - Polyethylene Terephthalate (PET) - and a flexible stainless steel sheath as a heating solution. The stiffness of PET can be flexibly adjusted through temperature. Experiments and validations were carried out at different conditions. The results showed that our proposed design is at least as flexible as a typical commercial endoscope when flexibility is desired and meanwhile at least 9 times stiffer than the endoscope when stiffness is desired (Flexural modulus was compared). A tendon-driven manipulator based on the proposed concept was also developed. Validation tests showed that the manipulator in compliant mode can be significantly bent through cable actuation, and the manipulator in stiff mode is able to maintain its shape against considerably large loads.

Cable-conduit mechanism (CCM) is widely used in robotic hands, rescue robots, rehabilitation robots, and surgical robots because it offers efficient transmission of forces/torques from the external actuator to the end effector with lightweight and high flexibility. However, the accurate position control is challenging in such mechanism due to friction and backlash-like hysteresis between the cable and the conduit. In this paper, a new control approach is proposed to enhance the trajectory tracking performances of the CCM. Unlike current approaches for the CCM in the literature, the proposed scheme considers the position transmission of the CCM as an approximation of backlash-like hysteresis nonlinearities without requiring the exact values of model parameters and their bounds. Online approximation-based robust control laws, which have the capabilities of estimating unknown system parameters, are also established. In addition, the deigned controller can adapt to any changes of the cable-conduit configuration and it is stable. The results of the proposed control techniques have been experimentally validated on a flexible robotic system using a flexible endoscope. Experimental validations show substantial improvements on the performances of position tracking for the use of CCM regardless of the arbitrary changes of the cable-conduit configurations.

Obesity is defined as an unhealthy excess of body fat, which increases the risks of medical illness and premature mortality. There are multiple health risks linked to obesity such as heart disease and stroke, high blood pressure, diabetes, cancers, gallbladder disease and gallstones, osteoarthritis, gout, and breathing problems like sleep apnea, and asthma. Intragastric balloons (IGBs) have become an efficient and less invasive method for obesity treatment. However, the use of traditional IGBs requires complex insertion tools and flexible endoscopes to place and remove the balloon inside patient's stomach. This causes abdominal discomfort, nausea, vomiting, and gastric mucous damage. To overcome these limitations, we designed a novel magnetic soft capsule robot for obesity treatment with magnetically actuated inflatable IGB. The balloon is made from a thin, flexible, biocompatible material, and is inflated to a desired volume using biocompatible effervescent chemicals. Instead of using complex deflation mechanism, a biodegradable material is developed to automatically deflate the balloon after a predetermined period of treatment. In addition, multiple capsules can be simultaneously swallowed. As the source of actuation is provided via external magnetic fields, the magnetic soft capsule size can be significantly reduced with no limitations on the power consumption. A prototype of magnetic soft capsule is developed. Experiments are carried out to demonstrate the effectiveness of the proposed approach.

Natural Orifice Transluminal Endoscopic Surgery (NOTES) is a method that allows for performing complex operations via natural orifices without skin incisions. Its main tool is a flexible endoscope. Cable-Conduit Mechanisms (CCMs) are often used in NOTES because of its simplicity, safety in design, and easy transmission. Backlash hysteresis nonlinearities between the cable and the conduit pose difficulties in the motion control of the NOTES system. It is challenging to achieve the precise position of robotic arms when the slave manipulator inside the humans body. This paper presents new approaches to model and control for pairs of CCMs. It is known that the change of cable-conduit configuration will affect the backlash hysteresis nonlinearities. To deal with such change, a new nonlinear and adaptive control scheme will be introduced. The backlash hysteresis parameters are online estimated under the assumption of availability of output feedback and unknown bound of nonlinear parameters. To validate the proposed approach, a prototype of single-DOF-Master-Slave system, which consists of a master console, a telesurgical workstation, and a slave manipulator, is also presented. The proposed compensation scheme is experimentally validated using the designed system. The results show that the proposed control scheme efficiently improves the tracking performances of the system regardless of the change of endoscope configuration.

Minimally Invasive Surgery (MIS) has established a revolution in surgical communities, with its many advantages over open surgery. The need of more simplicity and high maneuverability makes the tendon sheath a very suitable mechanism in flexible endoscopic systems. Due to the restriction on size constraints and sterilization problems, traditional sensors cannot be mounted on the tool tips of a slave manipulator. Moreover, in the presence of nonlinear friction and hysteresis between the tendon and the sheath, it is extremely difficult to control the precise motion and sense the force during the operation. This paper proposes a new dynamic friction model to estimate the force at the end effector for the tendon sheath mechanism. The proposed friction model can adapt with any initial pretension of the tendon and any configuration of the sheath. The nonlinearities in both sliding and presliding regimes can be captured by using an internal state variable and functions dependent velocity and acceleration. A specific setup has been designed in order to measure the friction force between the tendon and the sheath. Finally, the validity of the identified model is confirmed by a good agreement of its prediction and experimental data.