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基于串联弹性驱动器的关节自对准食指外骨骼设计与分析
孙宁
2022-08-17
Pages120
Subtype博士
Abstract

脑卒中患者通常伴随肢体运动功能障碍,其中约有 2/3 的患者面临手部运动功能失常,使患者丧失生活自理能力。因此脑卒中患者在康复医师的指导下进行规范的运动康复训练,恢复其手部功能具有重要意义。但是目前康复治疗师的数量不足以满足巨大的康复市场需求。为了解决这个问题,研究人员采用手部外骨骼辅助脑卒中患者进行康复训练。良好的手部外骨骼需要满足辅助关节独立运动、舒适性、易于穿戴、安全性等要求,因此本文对手部外骨骼的关节自对准机构、柔性驱动器以及外骨骼-指骨之间连接装置等进行设计与分析。本文的创新点和主要工作包括以下几个方面:

1. 提出了一种能够辅助食指进行屈曲/伸展和内收/外展训练的关节自对准食指外骨骼,分析了针对掌指关节的空间机构运动相容性。依据手部解剖学可知,食指能够分别进行屈曲/伸展和内收/外展运动。为了辅助食指进行前述两种运动康复训练,本文设计了一种具有 3 个电机驱动的关节自对准食指外骨骼。针对掌指关节,提出了一种基于冗余自由度的耦合空间机构,实现人机关节转轴自对准。其次分析了针对掌指关节的空间机构运动相容性,建立了空间机构运动-静力学模型,并且在考虑摩擦力等阻力的情况下,分析了外骨骼对掌指关节的作用力。最后对食指外骨骼样机进行了运动学和静力学实验,与所知的已提出方案相比,本文所提方案的标准化关节作用力平方和降低了 65.8%。实验结果表明该外骨骼可实现屈曲/伸展和内收/外展训练,人机关节自对准,并且提高舒适性。

2. 研制了基于橡胶弹簧离合型串联弹性驱动器,能够实现小型化、轻量化并保证被动安全,并且针对橡胶弹簧迟滞特性,提出了基于改进型参数化高斯过程的迟滞建模方法。 相关研究表明,基于力控制策略的外骨骼机器人更有利于脑卒中术后患者的运动康复。因此本文提出了一种基于橡胶弹簧离合型串联弹性驱动器,以感知人机交互力,从而实现力控制。所提出的串联弹性驱动器采用环形橡胶弹簧,以实现小型化、轻量化。一个圆盘式摩擦离合装置串联于输入端与橡胶弹簧之间,提高了被动安全性。针对橡胶弹簧的迟滞特性所造成的力感知不准确问题,本文提出了一种基于改进型参数化高斯过程迟滞建模方法,其采用了一个由多个基本核函数组成的组合核函数。最后对基于橡胶弹簧离合型串联弹性驱动器进行了实验。与不带离合装置相比,所提出串联弹性驱动器在碰撞时所产生的交互力降低了 51.78%。与本文训练的其它迟滞建模方法相比,所提出迟滞建模方法的最大绝对值误差能够降低 7%。实验结果表明所提串联弹性驱动器能够提高机械安全性,并验证了所提迟滞建模方法的有效性。

3. 设计了基于半包裹型绑缚装置和串联弹性驱动器的食指外骨骼,并且在考虑手指指骨尺寸个体差异性的情况下,提出了一种以最小化指骨切向力为目标的两层优化方法,对外骨骼的连杆长度进行了优化。基于前两部分的研究成果,本文设计了基于橡胶弹簧离合型串联弹性驱动器的食指外骨骼。针对现有绑缚装置穿戴复杂以及连接不稳定等问题,本文提出了一种半包裹型绑缚装置。然后分析了针对近端指间关节的外骨骼机构运动相容性,建立了近端指间关节外骨骼机构的运动-静力学。为了避免指骨切向力对手指造成损伤,本文在考虑手指指骨尺寸个体差异性的情况下提出了一种以最小化指骨切向力为目标的两层优化方法。最后对改进的食指外骨骼进行了实验测试。与优化前相比,优化后的近端指间关节外骨骼部分对指骨所产生的指骨切向力的最大值降低了 23.65%。实验结果表明该外骨骼能够提高穿戴/脱离便捷性、连接稳定性以及舒适性。

Other Abstract

Stroke patients usually have limb motor dysfunction. About 2/3 of the patients have hand motor dysfunction, which makes the patients lose the ability of taking care of themselves. Therefore, stroke patients must carry out standardized rehabilitation training under the guidance of therapists to recover the patients' lost hand motor function. However, the number of therapists is insufficient to meet the enormous rehabilitation market demand. To solve this problem, researchers proposed to use the hand exoskeleton robot to assist patients with hand rehabilitation training. A good hand exoskeleton needs to meet the requirements of auxiliary joint independent movement, comfort, ease of wearing, and safety. Therefore, the joint self-aligning mechanism, flexible actuator, and exoskeleton-phalange connector of hand exoskeleton are designed and analyzed in this dissertation. The innovation and main work of this dissertation are as follows:

1. A self-aligning index finger exoskeleton that can assist the index finger in the flexion/extension and adduction/abduction training is proposed, and the spatial mechanism's kinematic compatibility for the metacarpophalangeal joint is analyzed. According to the anatomy of the hand, the index finger can perform the flexion/extension and adduction/abduction motions, simultaneously. To assist the index finger in the above two kinds of rehabilitation training, a self-aligning index finger exoskeleton with three motors is proposed in this dissertation. Firstly, a spatial mechanism with redundant degrees of freedom for the metacarpophalangeal joint is designed to realize human-machine joint axis self-alignment. Secondly, the spatial mechanism's kinematic compatibility for the metacarpophalangeal joint is analyzed, and the kineto-statics analysis of the spatial mechanism is performed. Considering the friction and other resistances, the reaction forces generated by the exoskeleton on the metacarpophalangeal joint are analyzed. Finally, the kinematics and statics experiments of the index finger exoskeleton prototype are carried out. The standardized reaction forces square sum of the proposed exoskeleton to the metacarpophalangeal joint can be reduced by 65.8% compared with the known proposed exoskeleton. The experimental results show that the proposed index finger exoskeleton can achieve the flexion/extension and adduction/abduction training, human-robot joint motion axes self-alignment, and can improve its comfortability.

2. A miniaturized, lightweight, and passively safe elastomer-based clutched series elastic actuator is developed, and to counteract the hysteresis characteristics of rubber spring, an improved parametric Gaussian process regression hysteresis modeling method is proposed. Research has indicated that force-control-based strategies are more conducive to the rehabilitation of limbs. Therefore, an elastomer-based clutched series elastic actuator is proposed to perceive human-machine interaction forces and achieve force control. Firstly, the proposed series elastic actuator uses ring rubber spring to realize miniaturization and lightweight. A wafer disc clutch is connected in series between the input end and the rubber spring to improve the mechanical safety. Secondly, an improved parametric Gaussian process regression method is proposed to solve the problem of inaccurate force perception caused by the hysteresis characteristics of the rubber spring. A combined kernel function composed of multiple basic kernels is adopted. Finally, the experiments for the elastomer-based clutched series elastic actuator are performed. Compared with the case without the clutch, the force caused by collision on the proposed series elastic actuator is reduced by 51.78%. Maximum absolute error of the proposed hysteresis model can be reduced by 7% compared with those of other hysteresis models trained in this dissertation. The experimental results show that the proposed series elastic actuator can improve the mechanical safety, and the proposed hysteresis modeling method is effective.

3. An index finger exoskeleton with semi-wrapped fixture and series elastic actuator is designed, and considering the individual differences in the size of the phalanges, a two-level optimization method is proposed to minimize the tangential force of the phalanx, and the length of the links of the exoskeleton is optimized. Based on the research results of the first two parts of this dissertation, an index finger exoskeleton with the elastomer-based clutched series elastic actuator is designed. Firstly, to solve the problems of complex wearing and unstable connection of the existing fixtures, a semi-wrapped fixture is proposed. Secondly, the exoskeleton mechanism's kinematic compatibility for the proximal interphalangeal joint is analyzed. Thirdly, the kineto-statics of the exoskeleton mechanism for the proximal interphalangeal joint is analyzed. To avoid the damage caused by the tangential force of the phalanx, considering the individual difference in the size of the phalanges, this dissertation proposes a two-level optimization method to minimize the tangential force of the phalanx. Finally, the improved index finger exoskeleton is tested. Compared with the result before optimization, the maximum tangential force of the phalanx generated by the optimized proximal interphalangeal joint exoskeleton is reduced by 23.65%. The experimental results show that the proposed exoskeleton can improve the convenience of wearing/detaching, connection stability, and comfort.

Keyword食指外骨骼, 关节自对准机构, 串联弹性驱动器, 外骨骼-指骨连接装置
Language中文
Document Type学位论文
Identifierhttp://ir.ia.ac.cn/handle/173211/49696
Collection毕业生_博士学位论文
复杂系统管理与控制国家重点实验室_先进机器人
Recommended Citation
GB/T 7714
孙宁. 基于串联弹性驱动器的关节自对准食指外骨骼设计与分析[D]. 北京. 中国科学院大学,2022.
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