Development of a Wearable Upper Limb Rehabilitation Robot Based on Reinforced Soft Pneumatic Actuators

Dyskinesia of the upper limbs caused by stroke,sports injury,or trafc accidents limits the ability to perform the activities of daily living.Besides 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 limb.Conventional upperlimb rehabilitation robots have some disadvantages,such as a complex structure,poor compliance,high cost,and poor portability.In 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 developed.Driven by RSPAs,this portable SWULRR can perform rehabilitation training of the wrist and elbow joints.In this study,the kinematics of an SWULRR were analyzed,and the force and motion characteristics of RSPA were studied experimentally.The results provide a reference for the development and application of wearable upper limb rehabilitation robots.An 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 model.The process of wrist rehabilitation training was tested and evaluated,indicating that SWULRR with RSPAs will enhance the fexibility,comfort,and safety of rehabilitation training.This work is expected to promote the development of wearable upper-limb rehabilitation robots based on modular reinforced soft pneumatic actuators.

Soft pneumatic actuators by digital light processing combined with injection-assisted post-curing

The soft robotics display huge advantages over their rigid counterparts when interacting with living organisms and fragile objects.As one of the most efficient actuators toward soft robotics,the soft pneumatic actuator(SPA)can produce large,complex responses with utilizing pressure as the only input source.In this work,a new approach that combines digital light processing(DLP)and injection-assisted post-curing is proposed to create SPAs that can realize different functionalities.To enable this,we develop a new class of photo-cross linked elastomers with tunable mechanical properties,good stretchability,and rapid curing speed.By carefully designing the geometry of the cavities embedded in the actuators,the resulting actuators can realize contracting,expanding,flapping,and twisting motions.In addition,we successfully fabricate a soft self-sensing bending actuator by injecting conductive liquids into the three-dimensional(3D)printed actuator,demonstrating that the present method has the potential to be used to manufacture intelligent soft robotic systems.

Design of wearable hand rehabilitation glove with soft hoop-reinforced pneumatic actuator

Traditional hand rehabilitation gloves usually use electrical motor as actuator with disadvantages of heaviness,bulkiness and less compliance.Recently,the soft pneumatic actuator is demonstrated to be more suitable for hand rehabilitation compared to motor because of its inherent compliance,flexibility and safety.In order to design a wearable glove in request of hand rehabilitation,a soft hoop-reinforced pneumatic actuator is presented.By analyzing the influence of its section shape and geometrical parameters on bending performance,the preferred structure of actuator is achieved based on finite element method.An improved hoop-reinforced actuator is designed after the fabrication and initial measurement,and its mathematical model is built in order to quickly obtain the bending angle response when pressurized.A series of experiment about bending performance are implemented to validate the agreement between the finite element,mathematical and experimental results,and the performance improvement of hoop-reinforced actuator.In addition,the designed hand rehabilitation glove is tested by measuring its output force and actual wearing experience.The output force can reach 2.5 to 3 N when the pressure is 200 kPa.The research results indicate that the designed glove with hoop-reinforced actuator can meet the requirements of hand rehabilitation and has prospective application in hand rehabilitation.

Biomimetic soft robotic wrist with 3-DOF motion and stiffness tunability based on ring-reinforced pneumatic actuators and a particle jamming joint

The human wrist, a complex articulation of skeletal muscles and two-carpal rows, substantially contributes to improvements in maneuverability by agilely performing three-degree-of-freedom(3-DOF) orienting tasks and regulating stiffness according to variations in interaction forces. However, few soft robotic wrists simultaneously demonstrate dexterous 3-DOF motion and variable stiffness;in addition, they do not fully consider a soft-rigid hybrid structure of integrated muscles and two carpal rows.In this study, we developed a soft-rigid hybrid structure to design a biomimetic soft robotic wrist(BSRW) that is capable of rotating in the x and y directions, twisting around the z-axis, and possessing stiffness-tunable capacity. To actuate the BSRW, a lightweight soft-ring-reinforced bellows-type pneumatic actuator(SRBPA) with large axial, linear deformation(η_(lcmax)=70.6%,η_(lemax)=54.3%) and small radial expansion(η_(demax)=3.7%) is designed to mimic the motion of skeletal muscles. To represent the function of two-carpal rows, a compact particle-jamming joint(PJJ) that combines particles with a membrane-covered ballsocket mechanism is developed to achieve various 3-DOF motions and high axial load-carrying capacity(>60 N). By varying the jamming pressure, the stiffness of the PJJ can be adjusted. Finally, a centrally positioned PJJ and six independently actuated SRBPAs, which are in an inclined and antagonistic arrangement, are sandwiched between two rigid plates to form a flexible,stable, and compact BSRW. Such a structure enables the BSRW to have a dexterous 3-DOF motion, high load-carrying ability,and stiffness tunability. Experimental analysis verify 3-DOF motion of BSRW, producing force of 29.6 N and 36 N and torque of2.2 Nm in corresponding rotations. Moreover, the range of rotational angle and stiffness-tuning properties of BSRW are studied by applying jamming pressure to the PJJ. Finally, a system combining a BSRW and a soft enclosing gripper is proposed to demonstrate outstanding manipulation capability in potential applications.

Ultralong Stretchable Soft Actuator(US2A):Design,Modeling and Application

Actuator plays a significant role in soft robotics.This paper proposed an ultralong stretchable soft actuator(US2A)with a variable and sizeable maximum elongation.The US2A is composed of a silicone rubber tube and a bellows woven sleeve.The maximal extension can be conveniently regulated by just adjusting the wrinkles’initial angle of the bellows woven sleeve.The kinematics of US2A could be obtained by geometrically analyzing the structure of the bellows woven sleeve when the silicone rubber tube is inflated.Based on the principle of virtual work,the actuating models have been established:the pressure-elongation model and the pressure-force model.These models reflect the influence of the silicone tube’s shell thickness and material properties on the pneumatic muscle’s performance,which facilitates the optimal design of US2A for various working conditions.The experimental results showed that the maximum elongation of the US2A prototype is 257%,and the effective elongation could be variably regulated in the range of 0 and 257%.The proposed models were also verified by pressure-elongation and pressure-force experiments,with an average error of 5%and 2.5%,respectively.Finally,based on the US2A,we designed a pneumatic rehabilitation glove,soft arm robot,and rigid-soft coupling continuous robot,which further verified the feasibility of US2A as a soft driving component.

Pneu-net型变曲率软体驱动器弯曲性能与控制的研究

气动软体驱动器是气动软体机器人的基础和关键元件,在实现软体机器人弯曲运动方面有着无可比拟的优势。但是气动软体驱动器在结构和材料方面都存在明显的非线性,这对软体驱动器的建模和精确控制提出了很大的挑战。本文基于分段常曲率变形假设、Yeoh超弹性材料本构模型和虚功原理建立了pneumatic networks (pneu-net)型常曲率软体驱动器的弯曲数学模型,通过有限元仿真研究了结构参数和输入气压对驱动器弯曲性能的影响。在此基础上提出了变参数变曲率驱动器设计,建立了其弯曲变形预测模型,并进行了多驱动器一致性误差分析,有限元仿真和实验验证了模型的有效性。最后对软体驱动器的力输出特性进行了实验测试,制作了一个三指软体抓手,通过实验展示了软体抓手抓持不同物体的性能。

基于改进三元模型的波纹管型气动软体驱动器神经网络滑模控制

针对一款波纹管型气动软体驱动器,提出了一种基于改进三元模型的滑模控制方法,并使用RBF神经网络补偿扰动以实现该型驱动器在竖直方向上对期望轨迹的跟踪控制。首先搭建波纹管型气动软体驱动器实验平台,测试并分析该驱动器的动态特性,基于上述动态特性提出波纹管型气动软体驱动器的改进三元模型;然后利用采集到的实验数据,基于最小二乘算法对其进行参数辨识,从而获得所提模型的参数;进而结合改进三元模型设计滑模控制器,使用RBF神经网络对集总扰动进行补偿,并利用Lyapunov方法分析系统的稳定性;最后通过一系列实验验证了所提方法的有效性。

Pneumatic and tendon actuation coupled muti-mode actuators for soft robots with broad force and speed range

Broad output force and speed ranges are highly desired for actuators to endow soft robots with high performance,thereby increasing the range of tasks they can accomplish.However,limited by their low structural stiffness and single actuation method,most of the existed soft actuators are still difficult to achieve a broad force and speed range with a relatively compact body structure.Here,we propose a pneumatic and tendon actuation coupled soft actuator(PTCSA)with multiple actuation modes,mainly composing of a multi-joint thermoplastic polyurethanes(TPU)-made skeleton sealed in a film sleeve.The TPU skeleton with certain structural stiffness combined with soft joints allows PTCSA to output small force and respond rapidly under pneumatic actuation,as well as output high force and flexibly regulate response speed under tendon actuation,therefore achieving a broad force and speed range with a compact structure.The multiple modes constructed from the two actuation methods with different force and speed properties can cover diverse application scenarios.To demonstrate its performance,PTCSA is further used to construct a soft robotic arm(with a maximum lifting speed of 198°/s and can easily lift a load of 200 g),an inchworm-inspired wheel-footed soft robot(moves at a high speed of 2.13 cm/s when unload or pulls a load of 300 g forward),and a soft gripper(can grasp diverse objects,from 0.1 g potato chips to an 850 g roll of Sn-0.7 Cu wire,from a high-speed moving tennis ball to an upright pen).This work indicates the potential of combining multiple complementary actuation methods to improve the force and speed range of soft actuators,and may provide inspiration for related research.

Investigation of mechanical and electrical characteristics of selfsensing pneumatic torsional actuators

Soft pneumatic actuators are one of the most promising actuation for soft robots,and great achievements have been obtained.But it remains challenging to endow sensing capabilities to pneumatic actuators,especially for the sensing ability originating directly from the actuator architecture.Herein,a self-sensing pneumatic torsional actuator(SPTA)is designed based on the electromagnetic induction effect and magnetically responsive materials.The SPTA can generate feedback voltage and current with the deformation,in which the sensing function comes from its inherent structure.To investigate the mechanical and electrical characteristics,an experimental platform and a finite element model are established,respectively.We find that the torsion angle and output torque increase in nonlinear with the actuating pressure.The maximum torsion angle is 66.35°,which is 84.34%of that for the actuator fabricated by pure rubber.The maximum output torque(24.9 N mm)improves by 23.19%compared with the actuator made by pure rubber.As regards the electrical characteristics,the maximum feedback voltage and current are 2.90μV and 29.50 nA when the SPTA is actuated by a pressure of−40 kPa.We also demonstrate that the relationship between the torsion angle and the magnetic flux change is approximately linear.Finally,the number of turns of wires,magnetic powders contents,and magnetic direction on the feedback voltage and current are studied.Results show that the feedback voltage and current can be enhanced by increasing the number of turns and magnetic powders contents.We envision that the SPTA would be promising for soft robots to realize their accuracy control and intelligentization.

Modular crawling robots using soft pneumatic actuators

Crawling robots have elicited much attention in recent years due to their stable and efficient locomotion.In this work,several crawling robots are developed using two types of soft pneumatic actuators(SPAs),namely,an axial elongation SPA and a dual bending SPA.By constraining the deformation of the elastomeric chamber,the SPAs realize their prescribed motions,and the deformations subjected to pressures are characterized with numerical models.Experiments are performed for verification,and the results show good agreement.The SPAs are fabricated by casting and developed into crawling robots with 3D-printing connectors.Control schemes are presented,and crawling tests are performed.The speeds predicted by the numerical models agree well with the speeds in the experiments.

刚度增强型气动软体驱动器优化设计与试验

针对软体机器人刚度不足的问题,设计了一种内置弹性骨架的刚度增强型气动软体驱动器。基于二参数Yeoh模型建立驱动器材料本构模型,通过拉伸试验获得材料参数。利用有限元分析软件优化驱动器设计,分别对气囊结构、几何参数,纤维线径、缠绕角,弹性骨架刚度等进行仿真分析,获得设计参数对驱动器弯曲角度和刚度的影响规律。由仿真结果可知:具有扇形截面气腔、较大长径比、较薄外壁厚、较大腔室角及较细纤维线径的驱动器能提供更高柔性,而内置的弹簧骨架能够在保证柔性的同时提升刚度。根据优化设计结论,制作驱动器样机并进行试验验证。结果表明:设计的软体驱动器动作灵活柔顺,在0.16 MPa气压下弯曲角度可达55°,增设适宜骨架后,刚度提升了65.4%。

创新的多腔气动执行器——一种化学反应驱动的机械爬行运动生成装置

气动执行器的低成本制造和快速响应特性已经吸引了软体机器人领域研究者的广泛关注。仿生设计作为气动执行器主流设计理念之一,为研究者提供了灵感源泉,大多数现有的执行器都基于仿生设计。文中提出了一种仿蚯蚓设计的爬行机器人用气动软执行器。该执行器由多个网状气腔组成,并通过有限元分析优化了其主要参数,使其能够执行各种复杂动作。此外,在大多数现有的气动执行器中,气源由空气泵提供,而文中设计的执行器则由化学反应驱动。通过控制原材料的类型和比例,引发不同的化学反应,导致周期性的吸气和呼气,使执行器能够按照预期执行重复性动作。根据这些原理,将展示3种不同的步态,这种驱动方式可以有效地与爬行机器人的机械运动相结合,增强软体机器人的自主性和环境适应性。

软体弯曲驱动器设计与建模

与传统的"刚性"机器人相比,基于仿生学启发的软体机器人由于其与生俱来的柔顺性和安全性受到广泛关注。然而,此类软体机器人驱动器的设计与控制目前仍缺少理论指导。针对这些问题,设计了一种由气压驱动的可实现弯曲运动的新型软体驱动器,在系统分析其结构和弯曲原理的基础上,利用几何方法和虚功原理建立了其数学模型,并且通过有限元模型和原理样机实验验证了数学模型的有效性,为软体机器人驱动器的优化设计和控制提供了依据。

基于柔性气压驱动器的可穿戴式腰部助力机器人研究

针对老龄化社会对于康复和看护助力搬运的需要,提出了用气压驱动器实现轻量、柔性助力、穿戴舒适的可穿戴式腰部助力机器人.机器人采用无外骨骼的结构设计,可以给护理人员在提升重物和静态保持作业时输出腰部所需助力,降低下腰痛(Low back pain,LBP)致病风险.通过对重物搬运作业中穿戴者竖脊肌表面肌电信号(Surface electromyography,s EMG)评估、基于测力平台最大搬举重量测试、静态弯腰负重作业下人体重心(Center of gravity,COG)移动轨迹等相关实验,验证了助力有效性.

双作用气动软体驱动器的设计与分析

为模仿环节动物的纵肌与环肌功能,实现驱动器径向运动和轴向运动的拮抗作用,设计了一种双腔体双作用的气动软体驱动器。该软体驱动器由可实现轴向伸长运动的内腔轴向驱动器和可实现径向膨胀变形的外腔径向驱动器组成。为提高性能,软体驱动器外部结构采用了折叠方式,并通过有限元仿真分析了不同折叠参数对性能的影响。经实验测试,在0. 03 MPa的通气压力下,六折叠结构软体驱动器最大轴向伸长率可达到24. 2%,实现了对环节动物纵肌与环肌功能的模仿。

气动软体爬行机器人驱动方式的分析与实验

为研究基于蠕动原理的仿生爬行机器人运动,以气动弯曲驱动器和伸长驱动器为机器人主体,设计了一种软体爬行机器人。针对爬行机器人在平面及管道中的运动,根据爬行机器人的力学特性和运动过程中摩擦力与驱动力之间的关系,分析了爬行机器人实现爬行运动的条件,提出了爬行机器人驱动方式。通过实验,验证了所提出的驱动方式能够实现软体爬行机器人的移动,为今后软体爬行机器人的研究及应用提供了基础。

多腔体式仿生气动软体驱动器的设计与制作

软体驱动器是一种由柔软材料组成,并主要通过弹性材料的弯曲、收缩或伸长等来实现运动的执行器。软体驱动器是实现仿生软体机器人运动和动作的关键部分,开发适用的软体驱动器是进行仿生软体机器人研究的前提。为研究能够驱动软体机器人的仿生软体驱动器,基于目前常见的软体驱动器形式,提出并设计了一种多腔体式仿生气动软体驱动器。该气动软体驱动器主体结构采用硅胶材料制作,能够利用3D打印的模具进行成型。该驱动器主体结构加上底面或经组合后,可以分别得到伸长驱动器、单向弯曲驱动器及双向弯曲驱动器,能够实现类似身体柔软类动物的仿生变形运动。分别对上述3种软体驱动器的静态特性进行了测试,结果表明,在15kPa压力下伸长驱动器的伸长率能够达到40%以上,弯曲驱动器在同样压力下也具有较大的弯曲变形。经实践证明,所设计的多腔体式仿生气动软体驱动器原理可行、制作工艺简单,能够在软体机器人及相关领域中得到广泛应用。

用于康复训练的分段式气动软体驱动器

针对手指康复训练中软体驱动器贴合度低、灵活性差、运动传递不准确等问题,基于仿生原理设计分段式气动软体驱动器.通过3个具有锯齿结构半波纹管气囊实现软体驱动器的分段弯曲,嵌入柔性应变传感器实现软体驱动器本体感知.建立半波纹管气囊弯曲变形数学模型,借助有限元分析对半波纹管气囊进行分析,研究壁厚、波纹宽度、波距和波纹数目对该气囊弯曲性能和末端输出力的影响,选取软体驱动器尺寸参数.采用3D打印技术及失蜡铸造工艺,制作分段独立驱动的软体驱动器.特性测试结果表明:分段式软体驱动器最大弯曲角度为302°,末端输出力为3.33 N,能够带动手指进行分关节康复训练,内嵌的柔性应变传感器可以实时监测软体驱动器弯曲状态.

高伸缩比气动软体驱动器刚度特性研究

对一款由乳胶气囊、纤维布等材料组成的高伸缩比气动软体驱动器的刚度特性展开研究。根据软体驱动器的结构特点,采用理论与实验相结合的方法,改进软体驱动器的静态输出力模型,建立软体驱动器的静态刚度模型;并结合气体多变方程,建立软体驱动器的动态刚度模型,动态刚度为静态刚度与气压刚度之和;搭建软体驱动器静态刚度实验平台并对其静态刚度进行实验研究。结果表明:软体驱动器的静态刚度随膨胀高度的增大而减小,具有良好的线性关系和较小的相对误差,当供气压力为70 kPa时,软体驱动器静态刚度可达15 kN/m左右。对气压刚度进行仿真分析,结果表明:气压刚度主要受膨胀高度、供气压力以及激励位移的影响,当软体驱动器膨胀高度为30 mm、供气压力为10 kPa、激励位移为5 mm时,气压刚度仅为静态刚度的1/6左右。

双向气动软体执行器的设计与分析

设计了由两种尺寸气囊交替连通而成的新型软体执行器,该结构可实现两个方向固定角度摆动.首先建立双向弯曲软体执行器的非线性力学模型,得到形式为三段的分段函数,每一段表示软体执行器在相应阶段的弯曲角度和驱动气压的函数关系.其次,应用仿真软件描绘出软体执行器的摆动角度和驱动气压的线性关系,并与经典软体执行器进行了对比,发现两者不同之处在于未充气侧大小气囊之间挤压的弹性势能.最后,制作了双向固定角度摆动的软体执行器模型,通过实验验证了数值结果的可靠性.结果表明,本文提出的双向弯曲气动网格软体执行器的非线性建模和设计是可行的.