The need for upper limb assistive and wearable exoskeletons is growing in various fields, e.g. either to support patients with neuromuscular disabilities or to reduce the effort strains on workers. These exoskeletons should reduce the efforts required by the user during functional tasks (dynamic consideration) and should fit the user’s size (geometric consideration). This is a tedious task, due to the 3D human-exoskeleton interactions, and to the complex and interdependent selection of the power transmission characteristics, i.e. motors or passive elements. There are still few guidelines and few clear procedures to support geometric and dynamic syntheses of these exoskeletons.

The objective of this study is to develop a procedure for geometric and dynamic syntheses of assistive upper limb exoskeletons, to serve as a tool to optimize their design.

Firstly, a geometric optimization of the exoskeleton dimensions enabled to satisfy the kinematic loop closures between the exoskeleton and the user for a maximum of positions while carrying out specific functional tasks and avoiding collisions with the body segments. Secondly, through an optimal control problem, the dynamic characteristics of the exoskeleton were obtained by minimizing the user’s joint torques for the functional tasks.

Closing the kinematic loops of the exoskeletons with optimized dimensions was achieved for all positions of the user while carrying out the functional tasks, which was 10.8% more than with a visual identification of the dimensions. The resulting dynamic parameters could reduce the user’s joint torque to less than 10.6% of the human-only simulations for nearly all joints and tasks.

These results showed that the geometric and dynamic synthesis procedures were successful. This is important, as it can enable the development of dedicated exoskeletons, such as lighter and smaller exoskeletons. The future perspectives will be to build an optimization framework, where the geometric and dynamic parameters could be optimized together, and to minimize the user’s muscle forces instead of joint torques for specific design purposes.

在各个领域，对上肢辅助和可穿戴外骨骼的需求正在增长，例如，以支持患有神经肌肉残疾的患者或减轻工人的劳累负担。这些外骨骼应减少用户在功能任务（动态考虑）期间所需的工作，并应适合用户的体型（几何考虑）。由于3D人机交互作用以及动力传输特性（即电动机或无源元件）的复杂且相互依存的选择，这是一项繁琐的任务。支持这些外骨骼的几何和动态合成的指南和明确程序仍然很少。

这项研究的目的是为辅助上肢外骨骼的几何和动态合成开发程序，以作为优化其设计的工具。

首先，外骨骼尺寸的几何优化使之能够满足外骨骼与使用者之间的运动学环路闭合的最大位置，同时执行特定的功能任务并避免与身体各部位的碰撞。其次，通过优化控制问题，通过使用户在执行功能任务时的关节扭矩最小化来获得外骨骼的动态特性。

在执行功能任务时，可以在用户的​​所有位置上关闭具有最佳尺寸的外骨骼运动环，这比视觉识别尺寸要高10.8％。对于几乎所有的关节和任务，所产生的动态参数可以将用户的关节转矩降低到仅人类模拟的不到10.6％。

这些结果表明几何和动态合成程序是成功的。这很重要，因为它可以开发专用的外骨骼，例如较轻和较小的外骨骼。未来的前景将是建立一个优化框架，在该框架中可以一起优化几何参数和动态参数，并最小化用户的肌肉力，而不是出于特定设计目的的关节扭矩。