For technical or medical applications, the knowledge of the exact kinematics of the human hand is key to utilizing its capability of handling and manipulating objects and communicating with other humans or machines. The optimal relationship between the number of measurement parameters, measurement accuracy, as well as complexity, usability and cost of the measuring systems is hard to find. Biomechanic assumptions, the concepts of a biomechatronic system and the mechatronic design process, as well as commercially available components, are used to develop a sensorized glove. The proposed wearable introduced in this paper can measure 14 of 15 angular values of a simplified hand model. Additionally, five contact pressure values at the fingertips and inertial data of the whole hand with six degrees of freedom are gathered. Due to the modular design and a hand size examination based on anthropometric parameters, the concept of the wearable is applicable to a large variety of hand sizes and adaptable to different use cases. Validations show a combined root-mean-square error of 0.99° to 2.38° for the measurement of all joint angles on one finger, surpassing the human perception threshold and the current state-of-the-art in science and technology for comparable systems.
For technical or medical applications, the knowledge of the exact kinematics of the human hand is key to utilize its capability to handle and manipulate objects as well as to communicate with other humans or machines. The optimum between the number of measurement parameters, measuring accuracy as well as complexity, usability and cost of the measuring systems is hard to find. Biomechanic assumptions, the concepts of a biomechatronic system and the mechatronic design process as well as the use of commercial available components are used to develop a sensorized glove. The proposed wearable here can measure 14 of 15 angular values of a simplified hand model introduced in this paper and five contact pressures as well as inertial data of the whole hand with a degree of freedom of six. Due to the modular design and a hand size examination based on anthropological parameters, the concept of the wearable is applicable for a large variety of hand sizes and adaptable to different use cases. Validations show an RMSE for the measurement of the joint angles of 0.99 ° to 2.38° surpassing the human perception threshold and the current state of the art in science and technology for comparable systems.
The parallel connection of technical and biological systems with a comparable mechanical behavior offers the possibility of reducing the interaction forces between those systems. Especially in the context of human–robot interaction (e.g., exoskeletons), it can improve user safety and acceptance at the same time. With this aim, we used antagonistic actuators with nonlinear compliance for a modular upper-extremity exoskeleton following biological paragons, mirroring the “blueprint” of its human user. In a test-bed setup, we compared antagonistic compliant actuation with antagonistic stiff, unilateral stiff and unilateral compliant actuation in the artificial “elbow joint” of the exoskeleton test bed. We show that this type of actuation allows the variation of the joint stiffness during motion, independent of the position. With the approach we propose, compliance leads to reduced force peaks and angular jerk, without sacrifices in terms of time constants and overshoot of amplitudes. We conclude that the presented actuation principle has considerable benefits in comparison to other types of exoskeleton actuation, even when using only commercially available and 3D printed components. Based on our work, further investigations into the control of compliant antagonistically actuated exoskeletons become realizable.
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