Force Feedback Control Research Articles

A Vision-Guided Robotic System for Safe Dental Implant Surgery

Background: Recent advancements in dental implantology have significantly improved outcomes, with success rates of 90–95% over a 10-year period. Key improvements include enhanced preplanning processes, such as precise implant positioning, model selection, and optimal insertion depth. However, challenges remain, particularly in achieving correct spatial positioning and alignment of implants for optimal occlusion. These challenges are pronounced in patients with reduced bone substance or complex anthropometric features, where even minor misalignments can result in complications or defects. Methods: This paper introduces a vision-guided robotic system designed to improve spatial positioning accuracy during dental implant surgery. The system incorporates advanced force-feedback control to regulate the pressure applied to bone, minimizing the risk of bone damage. A preoperative CBCT scan, combined with real-time images from a robot-mounted camera, guides implant positioning. A personalized marker holder guide, developed from the initial CBCT scan, is used for patient–robot calibration. The robot-mounted camera provides continuous visual feedback of the oral cavity during surgery, enabling precise registration of the patient with the robotic system. Results: Initial experiments were conducted on a 3D-printed mandible using a personalized marker holder. Following successful patient–robot registration, the robotic system autonomously performed implant drilling. To evaluate the accuracy of the robotic-assisted procedure, further tests were conducted on 40 identical molds, followed by measurements of implant positioning. The results demonstrated improved positioning accuracy compared to the manual procedure. Conclusions: The vision-guided robotic system significantly enhances the spatial accuracy of dental implants compared to traditional manual methods. By integrating advanced force-feedback control and real-time visual guidance, the system addresses key challenges in implant positioning, particularly for patients with complex anatomical structures. These findings suggest that robotic-assisted implant surgery could offer a safer and more precise alternative to manual procedures, reducing the risk of implant misalignment and associated complications.

The design and implementation of automated maintenance system for the first-wall based on dual-arm manipulator

This paper proposed a framework of a dual-arm-based robotic maintenance system, including visual recognition, trajectory planning, force feedback control and master–slave control. To meet the requirements of automated maintenance, we proposed an improved design for the structures of the first wall tiles and support boards, and established a complete communication structure for the maintenance system that can adapt to different hardware versions. Based on the proposed framework, an experimental platform with dual-arm manipulator was established to demonstrate the maintenance scenario of the FW of the blanket in Vacuum Vessel (VV). The experimental result verified the feasibility of automated robotic maintenance system applied to the future fusion reactor.

Research on dynamic game operation behavior of multi‐oligopoly car‐sharing operators considering off‐peak pricing factors

AbstractIn the practical evolution of shared vehicle systems, numerous societal factors come into play, such as inadequate parking infrastructure, battery capacity, and the budget for technological improvement. This study integrates the operational realities of shared vehicle systems with governmental carbon emission reduction policies and “double control” initiatives. Considering various perturbations, the paper constructs a Stackelberg short‐term model among diverse oligopolistic shared vehicle operators with technique sharing. It also develops a long‐term repeated game framework to scrutinize the impact of pertinent parameters on operators' decision variables and profits, along with system stability and complexity. The findings, elucidated through numerical analyses, reveal that the burgeoning sensitivity of users to energy conservation augments the overall shared vehicle market. The technique sharing mechanism boosts the benefit of the whole group of shared vehicle operators while diminishing the start‐up operators' revenue. In the long term, however, excessive price adjustments by SEV operators may lead to market chaos and profit erosion. Conversely, enhancing the adjustment coefficient of technological level levels by start‐up SEV2 operators may result solely in their own decision‐making becoming unmanageable. Finally, we found that both the methods of external force feedback control and parameter control are effective in restoring the chaotic market to stability.

A simulation approach for determining maximal control cycle time in force-compliant assembly under contact force/torque constraints

Abstract Determining the maximum force feedback control cycle time for an assembly task at a given force/torque threshold is an important basis for designing and evaluating the corresponding force-compliant assembly method. For this issue, this paper proposes a simulation method for determining the maximum force feedback cycle time. The feasible region of the assembly process pose is determined by Monte Carlo simulation. Based on the particle swarm optimization, the pose and motion direction that generate the maximum contact force are found in the feasible region. Finally, dynamic simulation is carried out to determine the maximum force feedback control cycle. Experiments carried out for single-hole assembly show that the proposed approach can effectively determine the maximum force feedback control cycle time, and has a comparative advantage in convergence and total time consumption.

A Disturbance Compensation Control Strategy for Rotational Speed Standard Device Based on AMB System.

The rotational speed standard device that can carry loads is the key device for calibrating passive rotational speed sensors. The rotor of the passive rotational speed sensor is connected to the rotor of the standard speed device through a coupling, and the standard reference speed is provided by the standard device. Due to the rotor eccentricity, the unbalanced force of the rotor occurs, and it can not only affect the rotational speed accuracy but can also damage the mechanical bearings of the standard speed device. To solve this issue, a method for suppressing the unbalanced force of the speed standard device based on an active magnetic bearing (AMB) force compensation system is proposed. First, the overall structure of the system is briefly introduced. Then, the force feedback control system model with the AMB as the force actuator is established, and a PI controller is designed to achieve the disturbed force control. Finally, a semi-physical simulation experimental platform is built to verify the effectiveness of the proposed method. The experimental results show that the AMB force compensation system can reduce 84.4%, 81.6%, and 79.8% of the unbalanced vibration force at the frequency of 30 Hz, 90 Hz, and 150 Hz, respectively.

Effects of squeezed vacuum field on force sensing for a dissipative optomechanical system

We investigate the force sensing of a mechanical membrane in a dissipative cavity optomechanical system (OMS) driven by a squeezed vacuum field accompanying a strong pump laser. Specifically, the red-detuned laser exhibits a more significant improvement for force sensing compared to the blue-detuned laser. The optimal phase angle contributes to achieving much better force sensing. When injecting a squeezed vacuum field with appropriate squeezing parameter and squeezing phase, the standard quantum limit of force measurement can be easily beaten. Furthermore, the adverse effects of the increase in environment temperature and mechanical damping can be suppressed, simultaneously. This scheme provides a theoretical basics for force sensing of mechanical membranes in dissipative OMS and has potential applications in force feedback control, precision measurement, and force sensor design.

Experimental study on an enhanced integral force feedback controller for active damping

In this paper, an enhanced integral force feedback controller is proposed for implementing active damping. Compared with the classical integral force feedback, the pure integrator is replaced with a combination of a first-order low-pass filter and a proportional term. The control performance of the proposed controller is examined on a single-degree-of-freedom host system. In order to better understand the physics behind, a full equivalent mechanical model is derived. It is found that the first-order low-pass filter is mechanically equivalent to a spring and a damper connected in parallel. The proportional term mechanically represents a spring which is connected in series with the inherent actuator spring. The optimal control parameters are numerically obtained with the ℋ∞ optimisation criterion. The analysis shows that the optimal feedback gain can be practically taken the same as that of the classical integral force feedback controller in the sense that the difference between the resultant control performance is negligible. The numerical study is also experimentally validated. The obtained results are found to correspond well with the theoretical developments.

Human movement modifications induced by different levels of transparency of an active upper limb exoskeleton.

Active upper limb exoskeletons are a potentially powerful tool for neuromotor rehabilitation. This potential depends on several basic control modes, one of them being transparency. In this control mode, the exoskeleton must follow the human movement without altering it, which theoretically implies null interaction efforts. Reaching high, albeit imperfect, levels of transparency requires both an adequate control method and an in-depth evaluation of the impacts of the exoskeleton on human movement. The present paper introduces such an evaluation for three different "transparent" controllers either based on an identification of the dynamics of the exoskeleton, or on force feedback control or on their combination. Therefore, these controllers are likely to induce clearly different levels of transparency by design. The conducted investigations could allow to better understand how humans adapt to transparent controllers, which are necessarily imperfect. A group of fourteen participants were subjected to these three controllers while performing reaching movements in a parasagittal plane. The subsequent analyses were conducted in terms of interaction efforts, kinematics, electromyographic signals and ergonomic feedback questionnaires. Results showed that, when subjected to less performing transparent controllers, participants strategies tended to induce relatively high interaction efforts, with higher muscle activity, which resulted in a small sensitivity of kinematic metrics. In other words, very different residual interaction efforts do not necessarily induce very different movement kinematics. Such a behavior could be explained by a natural human tendency to expend effort to preserve their preferred kinematics, which should be taken into account in future transparent controllers evaluation.

Mixed-Reality-Based Teleoperation Grasping Control

Abstract Traditionally, teleoperation means that the system sends a series of signal commands from the master while the slave manipulator receives and realizes the desired control operations. For the purpose of implementing more dexterous and complex tasks, we propose a novel framework with dual-hand master teleoperation systems under time-varied delays. In this paper, we emphasize studying the bilateral grasping teleoperation control, as the time delay causes a communication outage. Combining a wave-variable structure with a four-channel framework, an event-trigger-based bilateral sliding mode teleoperation control and an adaptive neural network are designed to effectively achieve master-slave trajectory tracking. In the virtual 3D environment, we created a mixed-reality interface based on dual-hand master teleoperation control that effectively responded to the two Omni manipulators' position transformation of the virtual manipulator. The time delay between the real slave force feedback and the virtual interface is addressed by designed event-trigger-based control in order to efficiently reduce the impact of time communication outage. The system's stability is analyzed and robot experiments are performed. From the experimental results, the telepresence platform innovatively applied virtual force feedback to reveal the soft target grasping and to accurately estimate the interactive force, enabling sensorless force feedback control.

Feedback hybrid force and position control of an upper limb exoskeleton to support human movement

In the paper, a feedback hybrid control including a force feedback control and a position control is proposed to control a four degree of freedom (4-dof) upper limb exoskeleton for supporting human movement at the shoulder, elbow and wrist joints. The novelty of the paper is that it has been able to control all the interaction forces at all links in the exoskeleton robot by using the proposed control. The desired interaction forces at the links and desired position are compared with the measured interaction forces and position, respectively. Then the torque at the shoulder, the torque elbow and the torque wrist joints are controlled to compensate the force error and the position error. The gains of the proposed controller are optimized by using the Balancing Composite Motion Optimization (BCMO). The simulation and control of the 4-dof upper limb exoskeleton using the proposed control is carried out in the paper to show that the interaction forces and the position of the exoskeleton track their desired values.

Active Vibration Control of Wind Turbine Using Virtual TMD Algorithm Based on Aerodynamic-Structure-Servo Coupling Model

In order to extract more wind energy, the wind turbine rotor becomes larger and the tower becomes taller. With more flexibility and smaller damping, wind turbine tower is prone to vibrate in winds. Meanwhile, the tower suffers the periodic loadings caused by the rotor rotation in the operational condition. The excessive vibrations could not only significantly affect the power generation but shorten the structural life due to the fatigue as well. It is challenging to reduce the vibration caused by the rotor rotation using the passive tuned mass damper (TMD) and traditional LQR controller due to the limited effective bandwidth. Therefore, an active tuned mass damper (ATMD) using a virtual TMD algorithm is proposed to mitigate the along-wind vibration of the tower under parked and operational conditions. The virtual TMD algorithm exhibits wide effective bandwidth and only requires the acceleration information on the top of the tower or the relative displacement of the active TMD. Firstly, the aerodynamic-structure-servo coupling (ASSC) model of the wind turbine is established which considers the interaction among the aerodynamic load, structure, and servo system. Secondly, the accuracy of the ASSC model is then verified using the onshore 5 MW wind turbine by the National Renewable Energy Laboratory (NREL). Thirdly, the ATMD feedback control force is designed by the virtual TMD algorithm. Finally, the reduction effect on the along-wind vibration by the proposed controller is evaluated at both of operational and parked conditions using the ASSC model. The TMD and LQR controller are utilized for comparison. The numerical results demonstrate that tuned mass damper (TMD) system with fixed parameters becomes detuned and may loses its effectiveness at different wind speeds. In contrast, active control can suppress the vibration of wind turbines at different wind speeds. Compared to the LQR controller, the proposed controller can enhance the reduction effect of wind turbine response with smaller stroke and control force at operational conditions.

Improved precise guidewire delivery of a cardiovascular interventional surgery robot based on admittance control.

The development of cardiovascular interventional surgery robots can realize master-slave interventional operations, which will effectively solve the problem of surgeons being injured by X-ray radiation. The delivery accuracy and safety of interventional instruments such as guidewire are the most important issues in the development of robotic systems. Most of the current control methods are position control or force feedback control, which cannot take into account delivery accuracy and safety. A cardiovascular interventional surgery robotic system integrated force sensors is developed. A novel force/position controller, which includes a radial basis function neural networks-based inner loop position controller and a force-based admittance outer loop controller, is proposed. Furthermore, a series of simulations and vascular model experiments are carried out to demonstrate the feasibility and accuracy of the proposed controller. The designed cardiovascular interventional robot is flexible to enter the target vessel branch. Experimental results indicate that the proposed controller can effectively improve the delivery accuracy of the guidewire and reduce the contact force with the vessel wall. The proposed controller based on radial basis function neural network and admittance control is effective in improving delivery accuracy and reducing contact force. The algorithm needs to be further validated in vivo experiments.

Teleoperated Surgical Robot with Adaptive Interactive Control Architecture for Tissue Identification.

The remote perception of teleoperated surgical robotics has been a critical issue for surgeons in fulfilling their remote manipulation tasks. In this article, an adaptive teleoperation control framework is proposed. It provides a physical human-robot interaction interface to enhance the ability of the operator to intuitively perceive the material properties of remote objects. The recursive least square (RLS) is adopted to estimate the required human hand stiffness that the operator can achieve to compensate for the contact force. Based on the estimated stiffness, a force feedback controller is designed to avoid the induced motion and to convey the haptic information of the slave side. The passivity of the proposed teleoperation system is ensured by the virtual energy tank. A stable contact test validated that the proposed method achieved stable contact between the slave robot and the hard environment while ensuring the transparency of the force feedback. A series of human subject experiments was conducted to empirically verify that the proposed teleoperation framework can provide a more smooth, dexterous, and intuitive user experience with a more accurate perception of the mechanical property of the interacted material on the slave side, compared to the baseline method. After the experiment, the design idea about the force feedback controller of the bilateral teleoperation is discussed.

An Active Vibration Isolation and Compensation System for Improving Optical Image Quality: Modeling and Experiment.

Optical detection equipment (ODE) is subjected to vibrations that hamper the quality of imaging. In this paper, an active vibration isolation and compensation system (VICS) for the ODE is developed and systematically studied to improve the optical imaging quality. An active vibration isolator for cameras is designed, employing a dual-loop control strategy with position compensation and integral force feedback (IFF) control, and establishing the mapping relationship between vibration and image quality. A performance metric for evaluating images is also proposed. Finally, an experimental platform is constructed to verify its effectiveness. Based on the experimental results, it can be concluded that the proposed VICS effectively isolates vibrations, resulting in a reduction of 13.95 dB in the peak at the natural frequency and an 11.76 Hz widening of the isolation bandwidth compared with the system without it. At the same time, the experiments demonstrate that the image performance metric value increases by 46.03% near the natural frequency.

Design and calibration of spoke piezoelectric six-dimensional force/torque sensor for space manipulator

The large manipulator outside the space cabin is a multi-degree of freedom actuator for space operations. In order to realize the automatic control and flexible operation of the space manipulator, a novel spoke structure piezoelectric six-dimensional force/torque sensor with redundancy ability, high stiffness and good decoupling performance is innovatively proposed. Based on the deformation coordination relationship, the redundancy measurement mechanism is revealed. The mathematical models of the sensor with and without branch fault are established respectively. The finite element model is established to verify the feasibility of structure and redundancy measuring principle of the sensor. Depending on the theoretical analysis and simulation analysis, the prototype of the sensor is developed. Static and dynamic calibration experiments are carried out. The actual output voltage signal of the six-dimensional force/torque sensor is collected to establish the equation between the standard input applied load and the actual output voltage signal. Based on ant colony optimized BP algorithm, performance indexes of the sensor with and without branch fault are analyzed respectively. The experimental results show that the spoke piezoelectric six-dimensional force/torque sensor with the eight-point support structure has good accuracy and reliability. Meanwhile, it has strong decoupling characteristic that can effectively shield the coupling between dimensions. The nonlinear errors and maximum interference errors of decoupled data with and without branch faults are less than 1% and 2%, respectively. The natural frequency of the six-dimensional force sensor can reach 2856.45 Hz and has good dynamic characteristics. The research content lays a theoretical and experimental foundation for the design, development and application of the new six-dimensional force/torque sensors with redundancy. Meanwhile, it will significantly improve the research level in this field, and provide a strong guarantee for the smooth implementation of force feedback control of the space station manipulator project.

Design and evaluation of vascular interventional robot system for complex coronary artery lesions.

At present, most vascular intervention robots cannot cope with the more common coronary complex lesions in the clinic. Moreover, the lack of effective force feedback increases the risk of surgery. In this paper, a vascular interventional robot that can collaboratively deliver multiple interventional instruments has been developed to assist doctors in the operation of complex lesions. Based on the doctor's skills and the delivery principle of interventional instruments, the main and slave manipulators of the robot system are designed. Haptic force feedback is generated through resistance measuring mechanism and active drag system. In addition, a force feedback control strategy based on force-velocity mapping is proposed to realize the continuous change of force and avoid vibration. The proposed robot system was evaluated through a series of experiments. The experimental results show that the system can accurately measure the delivery resistance of interventional instruments, and provide haptic force feedback to doctors. The capability of the system to collaboratively deliver multiple interventional instruments is effective. Therefore, it can be considered that the robot system is feasible and effective.

Optimization of Structure and Control Technology of Tunnel Magnetoresistive Accelerometer

In this work, an optimized tunnel magnetoresistive (TMR) accelerometer with a closed-loop control system was developed and evaluated. The device first introduces a silicon spring–mass sensing structure lower than 50 Hz into TMR-based accelerometry for enhancing the mechanical sensitivity and subsequent readout sensitivity. Simultaneously, in order to realize the in-plane electrostatic feedback control, the comb structure is designed along with the sensing mechanism, owning combined benefits of integrated processing and large feedback force. The whole sensing structure is a silicon-glass chip, fabricated by the standard micro-electromechanical system (MEMS) process—deep dry silicon on glass (DDSOG) process. A permanent rubber magnet is assembled on the proof mass for conversion from the displacement to variation of the magnetic field intensity, which is further detected by a pair of symmetrically arranged TMR sensors. The voltage signals output from TMR sensors are then sent into an analog circuit via an interface module for force-feedback control. The simulation analysis indicates that the proposed MEMS sensing structure has a low natural frequency of 44.55 Hz, corresponding to a compliant mechanical sensitivity of 125.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> /g. Meanwhile, a maximum magnetic sensitivity of about 0.1 mT/mm is available in a height of 6 mm above the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3\times 3\times0.3$ </tex-math></inline-formula> mm magnet. Finally, the experiments on the assembled prototype demonstrated that a scale factor of 1.79 V/g and a bias stability of 228 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{g}$ </tex-math></inline-formula> have been achieved in the closed-loop modality, which verifies the effectiveness of the proposed TMR MEMS accelerometer.

Development and Testing of a Durable and Novel Breast Phantom for Robotic Autonomous Ultrasound Systems

For the safe and effective development of evolving autonomous medical robotic systems that traverse the surface of the body, like in breast ultrasound scans, developing phantoms that are durable and mechanically mimic human tissue is critical. In this work, a long lasting, inexpensive, and geometrically customizable phantom is described with mechanical and ultrasound acoustic properties that simulate human breast tissue. In comparison to prior work, a priority was designing a highly elastic phantom outer layer modulus 20 kPa and inner semi-liquid layer to mimic the difficulties of traversing human breast tissue with autonomous medical robotic systems. In addition, ultrasound images of the novel phantom with enclosed tumor are similar to in vivo image of human breast tissue with invasive ductal carcinoma, representing 80% of breast cancer cases. The performance of a force feedback controller on an autonomous ultrasound scanning system was compared for the novel phantom and a commercial phantom. Overall, the controller performed worse on the novel phantom — highlighting the importance of testing autonomous systems on realistic phantoms.

Dynamics analysis of knee joint during sit-stand movement

Sit-stand movement is one of the most common movement behaviors of the human body. The knee joint is the main bearing joint of this movement. Thus, the dynamic analysis of knee joint during this movement has deeply positive influences. According to the principle of moment balance, the dynamics of the knee joint during the movement were analyzed. Furthermore, combined with the data obtained from optical motion capture and six-dimensional ground reaction force test, the curve of knee joint torque was calculated. To verify the accuracy of the analysis of dynamic, the human body model was established, the polynomial equations of angle and angular velocity were fitted according to the experimental data, and the knee joint simulation of the movement was carried out. The result revealed that in terms of range and trend, the theoretical data and simulation data were consistent. The relationship between knee joint torque and ground reaction force was revealed based on the variation law of knee joint torque. During the sit-stand movement, the knee joint torque and the ground reaction force were directly proportional to each other, and the ratio was 5 to 6. In the standing process, the acceleration first increased and then decreased and finally increased in reverse, and the maximum knee torque occurred at an angle of about 140°. In the sitting process, the torque was maximized in the initial stage. The results of the dynamics analysis of knee joint during sit-stand movement are beneficial to the optimal design and force feedback control of seated rehabilitation aids, and can provide theoretical guidance for knee rehabilitation training.

Encouraging and Detecting Preferential Incipient Slip for Use in Slip Prevention in Robot-Assisted Surgery.

Robotic surgical platforms have helped to improve minimally invasive surgery; however, limitations in their force feedback and force control can result in undesirable tissue trauma or tissue slip events. In this paper, we investigate a sensing method for the early detection of slip events when grasping soft tissues, which would allow surgical robots to take mitigating action to prevent tissue slip and maintain stable grasp control while minimising the applied gripping force, reducing the probability of trauma. The developed sensing concept utilises a curved grasper face to create areas of high and low normal, and thus frictional, force. In the areas of low normal force, there is a higher probability that the grasper face will slip against the tissue. If the grasper face is separated into a series of independent movable islands, then by tracking their displacement it will be possible to identify when the areas of low normal force first start to slip while the remainder of the tissue is still held securely. The system was evaluated through the simulated grasping and retraction of tissue under conditions representative of surgical practice using silicone tissue simulants and porcine liver samples. It was able to successfully detect slip before gross slip occurred with a 100% and 77% success rate for the tissue simulant and porcine liver samples, respectively. This research demonstrates the efficacy of this sensing method and the associated sensor system for detecting the occurrence of tissue slip events during surgical grasping and retraction.