The parallel mechanism (PM) with a configurable movable platform (CMP) holds the potential for achieving a high-response speed and high-stiffness integrated design of a gripper-wrist system. The motion of two rotation...
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Currently,two rotations and one translation(2R1T)three-degree-of-freedom(DOF)parallel mechanisms(PMs)are widely applied in five-DOF hybrid machining ***,there is a lack of an effective method to evaluate the configura...
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Currently,two rotations and one translation(2R1T)three-degree-of-freedom(DOF)parallel mechanisms(PMs)are widely applied in five-DOF hybrid machining ***,there is a lack of an effective method to evaluate the configuration stiffness of mechanisms during the mechanism design *** is a challenge to select appropriate 2R1T PMs with excellent stiffness performance during the design *** the operational status of 2R1T PMs,the bending and torsional stiffness are considered as indices to evaluate PMs'configuration ***,a specific method is proposed to calculate these stiffness ***,the various types of structural and driving stiffness for each branch are assessed and their specific values ***,a rigid-flexible coupled force model for the over-constrained 2R1T PM is established,and the proposed evaluation method is used to analyze the configuration stiffness of the five 2R1T PMs in the entire ***,the driving force and constraint force of each branch in the whole working space are calculated to further elucidate the stiffness evaluating results by using the proposed method *** obtained results demonstrate that the bending and torsional stiffness of the 2RPU/UPR/RPR mechanism along the x and y-directions are larger than the other four mechanisms.
Soft robotics focuses on addressing the locomotion problem in unstructured environments and the manipulation problem of non-cooperative objects,which inevitably leads to soft robots encountering multiple uncertainties...
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Soft robotics focuses on addressing the locomotion problem in unstructured environments and the manipulation problem of non-cooperative objects,which inevitably leads to soft robots encountering multiple uncertainties and ***,improving the robustness of soft robots in hostile environmental conditions has always been a *** methods usually improve this robustness through damage isolation,material elasticity,and self-healing *** contrast to existing methods,this paper proposes a method to improve the robustness of an untethered soft-swallowing robot based on the physical properties of fluids,such as the high specific heat capacity of water,the viscosity of soft glue,and the shear thickening of non-Newtonian *** on this method,we developed a soft-swallowing robot with enhanced heat resistance,damage tolerance,and impact mitigation capability by only replacing its fluid working *** show that the developed soft-swallowing robot can withstand high temperatures above 600°C,maintain high performance even after enduring hundreds of damages,and protect grasped object from more than 90%of external *** principle extends beyond the three fluids used in this *** fluids,such as magnetic fluid,can increase adhesion to metal materials,whereas oily fluids can reduce frictional resistance between soft ***,other solid materials with elasticity and compliance can serve as alternative working mediums for the soft-swallowing *** work contributes an effective method for fluid-dependent soft robotic systems to resist the damage from uncertain factors in harsh environments.
Overconstrained mechanism has the advantages of large bearing capacity and high motion reliability,but its force analysis is complex and difficult because the mechanism system contains *** the limb axial deformation,t...
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Overconstrained mechanism has the advantages of large bearing capacity and high motion reliability,but its force analysis is complex and difficult because the mechanism system contains *** the limb axial deformation,taking typical 2SS+P and 7-SS passive overconstrained mechanisms,2SPS+P and 7-SPS active overconstrained mechanisms,and 2SPS+P and 7-SPS passive-input overconstrained mechanisms as examples,a new force analysis method based on the idea of equivalent stiffness is *** equivalent stiffness matrix of passive overconstrained mechanism is derived by combining the force balance and deformation compatibility equations with consideration of axial elastic limb *** relationship between the constraint wrench magnitudes and the external force,limb stiffness is *** equivalent stiffness matrix of active overconstrained mechanism is derived by combining the force balance and displacement compatibility ***,the relationship between the magnitudes of the actuated wrenches and the external force,limb stiffness is *** with the equivalent stiffness of the passive overconstrained mechanism,an analytical relationship between the actuated forces of passive-input overconstrained mechanism and the output displacement,limb stiffness is ***,adaptability of the equivalent stiffness to overconstrained mechanisms is discussed,and the effect of the limb stiffness on overconstrained mechanisms force distribution is *** research results provide a theoretical reference for the design,research and practical application of overconstrained mechanism.
As the support mechanism of space-borne antennas,space deployable antenna mechanism belongs to complex multi-closed-loop coupling mechanism,configuration design and dynamic analysis are more difficult than general par...
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As the support mechanism of space-borne antennas,space deployable antenna mechanism belongs to complex multi-closed-loop coupling mechanism,configuration design and dynamic analysis are more difficult than general parallel *** this paper,an unequal-length scissors mechanism(ULSM)is proposed by changing the position of the internal rotational joint through a basic scissors mechanism.A scissors hoop-rib truss deployable antenna mechanism(SHRTDAM)is constructed by replacing the parabolic rib with the *** analysis of SHRTDAM is conducted,and the degree of freedom(DOF)of the whole antenna mechanism is analyzed based on screw theory,the result showed that it has only one *** and acceleration characteristics of SHRTDAM are obtained by the screw derivative and rotation *** on Lagrange equation,dynamic model of this mechanism is established,the torque required to drive the mechanism is simulated and verified by Adams and MATLAB *** addition,a ground experiment prototype of 1.5-m diameter was fabricated and a deployment test is conducted,which demonstrated the mobility and deployment performance of the whole *** mechanism proposed in this paper can provide a good reference for the design and analysis of large aperture space deployable antennas.
Developing large,soft grippers with high omnidirectional load(above 40 kg)has always been *** address this challenge by developing a powerful soft gripper that can grasp the human body based on a soft-enclosed graspin...
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Developing large,soft grippers with high omnidirectional load(above 40 kg)has always been *** address this challenge by developing a powerful soft gripper that can grasp the human body based on a soft-enclosed grasping structure and a soft-rigid coupling *** envelope size of the proposed soft gripper is 611.6 mm×559 mm×490.7 mm,the maximum grasping size is 417 mm,and the payload on the human body is more than 90 kg,which has exceeded most existing soft ***,the grasping force prediction of the gripper is achieved through theoretical *** primary contribution of this work is to overcome the size and payload limits of current soft grippers and implement a human-grasping experiment based on the soft-grasping method.
Current research on spherical parallel mechanisms(SPMs)mainly focus on surgical robots,exoskeleton robots,entertainment equipment,and other ***,compared with the SPM,the structure types and research contents of the SP...
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Current research on spherical parallel mechanisms(SPMs)mainly focus on surgical robots,exoskeleton robots,entertainment equipment,and other ***,compared with the SPM,the structure types and research contents of the SPM are not abundant *** this paper,a novel two-degree-of-freedom(2DOF)SPM with symmetrical structure is proposed and ***,the models of forward kinematics and inverse kinematics are established based on D-H parameters,and the Jacobian matrix of the mechanism is obtained and ***,the workspace of the mechanism is obtained according to inverse kinematics and link interference ***,rotational characteristics analysis shows that the end effector can achieve continuous rotation about an axis located in the mid-plane and passing through the rotation center of the ***,the rotational characteristics of the mechanism are proved,and motion planning is carried out.A numerical example is given to verify the kinematics analysis and motion ***,some variant mechanisms can be *** work lays the foundation for the motion control and practical application of this 2DOF SPM.
In today’s society,parallel manipulators(PMs)are widely used in industrial production,aerospace,and other fields,where their forward kinematic analyses often serve as the foundation for various tasks,such as design,c...
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In today’s society,parallel manipulators(PMs)are widely used in industrial production,aerospace,and other fields,where their forward kinematic analyses often serve as the foundation for various tasks,such as design,calibration,and *** the past few decades,this issue has seemingly been repeatedly addressed using various numerical methods,intelligent algorithms,and algebraic *** it is undeniable that solving the equations is easier with current technology,the problem of“how to formulate solvable equations”is often *** analysis issue typically involves establishing non-linear,multi-parameter,high-dimensional,and strong-coupled mathematical equations,which,from a geometric perspective,is also considered a process of solving a spatial *** considering the temporal dimension of motion between two isomorphic polytopes,based on calculus theory,it has been found that this non-linear problem can be transformed into the superposition of multiple iteratively linear ***,we propose an original method for the forward kinematic analysis of PMs,namely the finite-step-integration(FSI)*** this study,the mathematical principles and modeling methods of the FSI method are elucidated,and the modeling and programming processes of the FSI method are demonstrated using general 6-UPS and 3-UPS/S manipulators as *** the analysis of its unique algebraic structure,the methods for singularity determination and motion tracking characteristic analysis are *** method addresses the long-standing challenges in the forward kinematic modeling of PMs,which is applicable for design,calibration,and control,while also offering novel insights for modeling and solving certain non-linear engineering problems.
Deployable mechanism with preferable deployable performance,strong expansibility,and lightweight has attracted much attention because of their potential in aerospace.A basic deployable pyramid unit with good deployabi...
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Deployable mechanism with preferable deployable performance,strong expansibility,and lightweight has attracted much attention because of their potential in aerospace.A basic deployable pyramid unit with good deployability and expandability is proposed to construct a sizeable deployable ***,the basic unit folding principle and expansion method is *** configuration synthesis method of adding constraint chains of spatial closed-loop mechanism is used to synthesize the basic ***,the degree of freedom of the basic unit is analyzed using the screw theory and the link dismantling ***,the three-dimensional models of the pyramid unit,expansion unit,and array unit are established,and the folding motion simulation analysis is carried *** on the number of components,weight reduction rate,and deployable rate,the performance characteristics of the three types of mechanisms are described in ***,prototypes of the pyramid unit,combination unit,and expansion unit are developed to verify further the correctness of the configuration synthesis based on the *** proposed deployable mechanism provides aference for the design and application of antennas with a large aperture,high deployable rate,and *** has a good application prospect in the aerospace field.
Dyskinesia of the upper limbs caused by stroke,sports injury,or trafc accidents limits the ability to perform the activities of daily *** the necessary medical treatment,correct and scientifc rehabilitation training f...
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Dyskinesia of the upper limbs caused by stroke,sports injury,or trafc accidents limits the ability to perform the activities of daily *** the necessary medical treatment,correct and scientifc rehabilitation training for the injured joint is an important auxiliary means during the treatment of the efected upper *** upperlimb rehabilitation robots have some disadvantages,such as a complex structure,poor compliance,high cost,and poor *** this study,a novel soft wearable upper limb rehabilitation robot(SWULRR)with reinforced soft pneumatic actuators(RSPAs)that can withstand high pressure and featuring excellent loading characteristics was *** by RSPAs,this portable SWULRR can perform rehabilitation training of the wrist and elbow *** this study,the kinematics of an SWULRR were analyzed,and the force and motion characteristics of RSPA were studied *** results provide a reference for the development and application of wearable upper limb rehabilitation *** experimental study on the rotation angle of the wrist and the pressure of the RSPA was conducted to test the efect of the rehabilitation training and verify the rationality of the theoretical *** process of wrist rehabilitation training was tested and evaluated,indicating that SWULRR with RSPAs will enhance the fexibility,comfort,and safety of rehabilitation *** work is expected to promote the development of wearable upper-limb rehabilitation robots based on modular reinforced soft pneumatic actuators.
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