查看更多>>摘要：Bionic hands are promising devices for assisting individuals with hand disabilities in rehabilitation robotics.Controlled primarily by bioelectrical signals such as myoelectricity and EEG,these hands can compensate for lost hand functions.However,developing model-based controllers for bionic hands is challenging and time-consuming due to varying control parameters and unknown application environments.To address these challenges,we propose a model-free approach using reinforcement learning(RL)for designing bionic hand controllers.Our method involves mimicking real human hand motion with the bionic hand and employing a human hand motion decomposition technique to learn complex motions from simpler ones.This approach significantly reduces the training time required.By utilizing real human hand motion data,we design a multidimensional sampling proximal policy optimization(PPO)algorithm that enables efficient motion control of the bionic hand.To validate the effectiveness of our approach,we compare it against advanced baseline methods.The results demonstrate the quick learning capabilities and high control success rate of our method.
查看更多>>摘要：Inspired by the driving muscles of the human arm,a 4-Degree of Freedom(DOF)concentrated driving humanoid robotic arm is proposed based on a spatial double parallel four-bar mechanism.The four-bar mechanism design reduces the inertia of the elbow-driving unit and the torque by 76.65％and 57.81％,respectively.Mimicking the human pose regulation strategy that the human arm picks up a heavy object by adjusting its posture naturally without complicated control,the robotic arm features an integrated position-level closed-form inverse solution method considering both geometric and load capacity limitations.This method consists of a geometric constraint model incorporating the arm angle(φ)and the Global Configuration(GC)to avoid joint limits and singularities,and a load capacity model to constrain the feasible domain of the arm angle.Further,trajectory tracking simulations and experiments are conducted to validate the feasibility of the proposed inverse solution method.The simulated maximum output torque,maximum output power and total energy consumption of the robotic arm are reduced by up to 2.0％,13.3％,and 33.3％,respectively.The experimental results demonstrate that the robotic arm can bear heavy loads in a human-like posture,effectively reducing the maximum output torque and energy consumption of the robotic arm by 1.83％and 5.03％,respectively,while avoiding joints beyond geometric and load capacity limitations.The proposed design provides a high payload-weight ratio and an efficient pose control solution for robotic arms,which can potentially broaden the application spectrum of humanoid robots.
查看更多>>摘要：Inspired by the fast,agile movements of insects,we present a 1.9 g,4.5 cm in length,piezoelectrically driven,quadru-pedal microrobot.This microrobot uses a novel spatial parallel mechanism as its hip joint,which consists of two spatially orthogonal slider-crank linkages.This mechanism maps two inputs of two independent actuators to the decoupled swing and lift outputs of a leg,and each leg can produce the closed trajectories in the sagittal plane necessary for robot motion.Moreover,the kinematics of the transmission are analyzed,and the parameters of the flexure hinges are designed based on geometrical constraints and yield conditions.The hip joints,legs and exoskeletons are integrated into a five-layer standard laminate for monolithic fabrication which is composed of two layers of carbon fiber,two layers of acrylic adhesive and a polyimide film.The measured output force(15.97 mN)of each leg is enough to carry half of the robot's weight,which is necessary for the robot to move successfully.It has been proven that the robot can successfully perform forward and turn-ing motions.Compared to the microrobot fabricated with discrete components,the monolithically fabricated microrobot is more capable of maintaining the original direction of locomotion when driven by a forward signal and has a greater speed,whose maximum speed is 25.05 cm/s.
查看更多>>摘要：Continuum manipulators(CM)are soft and flexible manipulators with large numbers of degrees of freedom and can perform complex tasks in an unstructured environment.However,their deformability and compliance can deviate distal tip under uncertain external interactions.To address this challenge,a novel tension-based control scheme has been proposed to modu-late the stiffness of a tendon-driven CM,reducing the tip position errors caused by uncertain external forces.To minimize the tip position error,a virtual spring is positioned between the deviated and the desired tip positions.The proposed algorithm corrects the manipulator deviated tip position,improving tension distribution and stiffness profile,resulting in higher stiffness and better performance.The corresponding task space stiffness and condition numbers are also computed under different cases,indicating the effectiveness of the tension control scheme in modulating the manipulator's stiffness.Experimental validation conducted on an in-house developed prototype confirms the practical feasibility of the proposed approach.
查看更多>>摘要：Brain-controlled technology is the key technology in biological control,and the corresponding relationship between ani-mal brain nuclei and motor behavior is the core.The purpose of this study was to explore the motor nuclei of the medulla oblongata in carp.The carps were subjected to electrical stimulation and chemical stimulation experiments,respectively,in the water-free state,and the effective chemical stimulation sites were injected with the pontamine sky blue solution.The brain tissue sections were obtained by paraffin tissue section technology and the neutral red staining method.By comparing the positions of the brain nuclei shown in earlier studies,the motor nerve nuclei in the medulla oblongata were identified.The brain electrode was implanted into the motor nucleus of the medulla oblongata,and the underwater control experiment and behavioral tests were carried out with different electrical stimulation parameters.The results showed that the abducens nucleus(NVI)was the motor nucleus that controls the ipsilateral steering,and the facial nucleus(NVII)was the motor nucleus that controls the forward movement.By adjusting the stimulation voltage and the stimulation pulse number,the carp can be stably controlled to achieve a left-right steering motion of 30°-180° and a forward motion of more than 80 cm/s.This study indicated that the quantitative control of the steering and forward behavior of the carp can be achieved by electrical stimulation of the NVI and NVII,which provided a certain experimental basis for the accurate control of the carp robot.
查看更多>>摘要：Autonomous navigation is a fundamental problem in robotics.Traditional methods generally build point cloud map or dense feature map in perceptual space;due to lack of cognition and memory formation mechanism,traditional methods exist poor robustness and low cognitive ability.As a new navigation technology that draws inspiration from mammal's navigation,bionic navigation method can map perceptual information into cognitive space,and have strong autonomy and environment adaptability.To improve the robot's autonomous navigation ability,this paper proposes a cognitive map-based hierarchical navigation method.First,the mammals'navigation-related grid cells and head direction cells are modeled to provide the robots with location cognition.And then a global path planning strategy based on cognitive map is proposed,which can anticipate one preferred global path to the target with high efficiency and short distance.Moreover,a hierarchical motion controlling method is proposed,with which the target navigation can be divided into several sub-target navigation,and the mobile robot can reach to these sub-targets with high confidence level.Finally,some experiments are implemented,the results show that the proposed path planning method can avoid passing through obstacles and obtain one preferred global path to the target with high efficiency,and the time cost does not increase extremely with the increase of experience nodes number.The motion controlling results show that the mobile robot can arrive at the target successfully only depending on its self-motion information,which is an effective attempt and reflects strong bionic properties.
Sina KhajeiAbed KhorasaniMohammad Reza AfarineshVahid Sheibani...
866-876页
查看更多>>摘要：In previous studies,Periaqueductal Gray(PAG)stimulation was used to stop ratbots from moving.Due to the homology between the PAG and the intercollicular nucleus,which has been used for forward movement in birds,we investigated the possibility of PAG application to induce forward locomotion for the first time.Using a corridor maze,the traveled distances via PAG electrical stimulation were examined in nine Wistar male rats during three sessions.A custom-designed stimulator was developed to apply the stimulation.The results showed reductions in responses to stimulation over time.Accordingly,the traveled distances had negative slopes during the consecutive trials(in 8 out of the 9 rats),and the slope mean was significantly different from zero.There was a strong correlation between the stimulation parameters(electric Charge per Phase(CPP)and the Number of Pulses(NP))and the observed slopes.The negative Movement Slopes(MS)were highly correlated with the CPP and the NP,as the Pearson's linear correlation coefficients were-0.87 and-0.79,respectively.The MS-CPP coefficients of determination(R-squared)were also between 0.76 and 0.95.In addition,the MS-NP coefficients of determination were between 0.63 and 0.87.Thus,it is concluded that the electrical stimulation parameters influence the behavioral outcomes directly.Furthermore,the PAG area may be considered a suitable candidate for forward locomotion control in the future if the area is harnessed effectively to prevent undesirable chaotic behaviors.
查看更多>>摘要：To reveal the resonance suppression mechanism of the blood circulation in dragonfly wings,a numerical modeling method of dragonfly wings based on Voronoi diagrams is proposed,and the changes in mass,aerodynamic damping,and natural frequencies caused by blood circulation in veins are investigated.The equivalent mass of blood,boundary conditions,and aerodynamic damping are calculated theoretically.Modal analysis and harmonic response analysis of wing models with dif-ferent blood circulation paths are performed using the finite-element method(FEM).The vibration reduction ratio δ is intro-duced to compare the damping efficiency of different mass regions.Finally,a natural frequency testing device is constructed to measure the natural frequencies of dragonfly wings.The results indicate that the shape,mass,and natural frequencies of the dragonfly wing model constructed by numerical method agree well with reality.The mass distribution on the wing can be altered by blood circulation,thereby adjusting the natural frequencies and achieving resonance suppression.The high-est δ of 1.013 is observed in the C region when blood circulates solely in secondary veins,but it is still lower than the δ of 1.017 when blood circulates in complete veins.The aerodynamic damping ratio(1.19-1.79％)should not be neglected in the vibration analysis of the beating wing.
查看更多>>摘要：Total shoulder arthroplasty is a standard restorative procedure practiced by orthopedists to diagnose shoulder arthritis in which a prosthesis replaces the whole joint or a part of the joint.It is often challenging for doctors to identify the exact model and manufacturer of the prosthesis when it is unknown.This paper proposes a transfer learning-based class imbalance-aware prosthesis detection method to detect the implant's manufacturer automatically from shoulder X-ray images.The framework of the method proposes a novel training approach and a new set of batch-normalization,dropout,and fully convolutional layers in the head network.It employs cyclical learning rates and weighting-based loss calculation mechanism.These modifications aid in faster convergence,avoid local-minima stagnation,and remove the training bias caused by imbalanced dataset.The proposed method is evaluated using seven well-known pre-trained models of VGGNet,ResNet,and DenseNet families.Experimentation is performed on a shoulder implant benchmark dataset consisting of 597 shoulder X-ray images.The proposed method improves the classification performance of all pre-trained models by 10-12％.The DenseNet-201-based variant has achieved the highest classification accuracy of 89.5％,which is 10％higher than existing methods.Further,to validate and generalize the proposed method,the existing baseline dataset is supplemented to six classes,including samples of two more implant manufacturers.Experimental results have shown average accuracy of 86.7％for the extended dataset and show the preeminence of the proposed method.
查看更多>>摘要：The produced water from the oilfield was purified with filter material and then injected back into the ground.The serpentine filter material was easy to harden with the increase in filtration amount,which affected the water quality.A superhydrophilic/underwater oleophobic serpentine filter material was successfully prepared by a simple method of coating modification,which exhibited long-lasting filtration of oily water,good filtration and anti-fouling properties,and resistance to harden.The film-forming material of the superhydrophilic/underwater oleophobic coating was composed of SiO2 particles with small size,which could completely and evenly cover the filter particle.The weight loss was only 7.6％after mechanical stirring for 90 min.Compared with the original filter material,the superhydrophilic/underwater oleophobic serpentine filter mate-rial showed a better anti-fouling ability and resistance to harden.The filtration of crude oil emulsion and oil slick sewage showed a better backwashing performance.After 35 cycles of continuous filtration of suspended solids in wastewater,the backwashing rate reached 78.4％.The results provided an effective method for the filtration of oily wastewater in the oilfield.
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