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Item type:Publication, Access status: with files , Toward a gecko-inspired, climbing soft robotIn this paper, we present a gecko-inspired soft robot that is able to climb inclined, flat surfaces. By changing the design of the previous version, the energy consumption of the robot could be reduced, and at the same time, its ability to climb and its speed of movement could be increased. As a result, the new prototype consumes only about a third of the energy of the previous version and manages to climb slopes of up to 84◦. In the horizontal plane, its velocity could be increased from 2 to 6 cm/s. We also provide a detailed analysis of the robot's straight gait.Publicationtype: Journal ArticleScopus© Citations 28 241 270 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , On the origin of passive rotation in rotational joints, and how to calculate itIn this paper, a computation method for the output shaft’s rotation of a passive rotational joint, especially of one that is deployed on a parallel mechanism, is investigated. As an alternative to typical geometric or screw theory methods, we propose a new approach that is based on the comparison between any passive rotational joint with a reference spherical joint. As examples, we apply our method to a universal joint and a novel double joint whose passive rotation is difficult to calculate with traditional methods. c 2019 The Authors Proceedings in Applied Mathematics & Mechanics published by Wiley-VCH Verlag GmbH & Co. KGaA WeinheimPublicationtype: Conference Paper286 271 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Recycling-oriented design in soft robotics(Multidisciplinary Digital Publishing Institute (MDPI), 2019-08-12); Soft robotics is a novel approach in the field of robotics. Soft robots or soft actuators are typically polymer-based and are characterized by their flexibility and adaptability, which brings new far-reaching applications. Soft robotics is currently at the peak of its research. One circumstance that is also present in this age is constant climate change; there is a demand for sustainability. This goes hand in hand with the design of products that are suitable for recycling. Today, more is expected of an engineer than just function-oriented design. This article looks at soft robotics from the point of view of sustainability. Since nature operates in cycles, the aim is to design products in such a way that they can be introduced into cycles. Three recycling cycles for products can be distinguished, which take place during production, during product use, and after product life. Within the framework of this work, special design measures are reviewed for fluidic elastomer actuators - a characteristic type of soft actuators - so that they can be integrated into the recycling process.Publicationtype: Journal ArticleScopus© Citations 7 343 309 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Elastomeric Prepregs for Soft Robotics Applications(2019-05); Typically, soft robots that are driven with compressed air consist of two parts which are bonded together, a top and a strain-limiting bottom part. This communication describes the possibility to simplify the manufacturing process by using textile semi-finished products preimpregnated with liquid elastomer (prepregs) as the strain-limiting part, which can be stored at low temperatures with significant slower cross-linking reaction. For this, in long-term tests, three typical elastomers (Elastosil M 4601, Ecoflex 00–30, and Sylgard 184) are stored at −25 °C, and in a weekly cycle over 12 weeks, the viscosity is measured to determine the curing characteristics. It turns out that Elastosil M 4601 and Sylgard 184 are suitable for this application. For comparison, short-term viscosity measurements are conducted at room temperature in a 10 min cycle. The impregnability of several textiles (polyester/cotton blended fabric, nylon fabric, fleece, and flax fabric) is tested with the suitable elastomers. The applicability of prepregs for soft robotic applications is demonstrated by manufacturing soft bending actuators with various textile-elastomer combinations.Publicationtype: Journal Article234 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Passive Rotation of Rotational Joints and Its Computation MethodThis paper discusses the equivalence condition of the input and output rotation of a passive rotational joint and provides a general method to compute the output rotation angle. In a Stewart-Gough platform, the fixed base platform is usually connected to the moveable manipulator platform by six identical kinematic chains consisting of rotational joints and linear actuators. When using lead screws for the linear actuators, possible passive rotations of the rotational joints can be harmful because they may lead to additional length variations of the linear actuators or cause extra stresses if the rotations are obstructed. This paper provides a for computing these passive rotations by using vector comparison and demonstrates its application on the examples of a universal joint, a Rzeppa joint, and a Tracta joint.Publicationtype: Conference Paper209 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Assembly Modes of General Planar 3-RPR Parallel Mechanisms when Using the Linear Actuators’ OrientationsIn this paper, we show that the number of possible assembly modes for the general planar 3-RPR parallel mechanism, where P denotes active prismatic joints and R denotes passive revolute joints, can be significantly reduced when using the linear actuators’ orientations in-stead of their lengths. The linear actuators’ lengths lead to a univariate polynomial which can have up to six different solutions and thus provides up to six assembly modes. By measuring the orientations of the linear actuators, provided, e. g., by inertial measurement units, only two assembly modes exist. Furthermore, by using two orientations of the linear actuators in addition to the moveable manipulator platform’s orientation, only one assembly mode remains.Publicationtype: Conference Paper321 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A simple control strategy for increasing the soft bending actuator performance by using a pressure boostHigh-speed actuation of soft actuators requires high source pressure to transfer air as quickly as possible into the actuator. Allowing high source pressure and having the deformation angle as the only control input may allow faster actuation, but there is a risk of bursting when the actuator is prevented from reaching the desired angle, for example, due to an obstacle. The other option to control the actuator’s deformation is based on controlling the pressure. In this paper, we present a simple control strategy that uses an initial pressure boost in a pressure-based PID controller showing the same performance as in angle-based PID control. The performance improvement is demonstrated experimentally on a standard soft bending actuator and a gecko-inspired, climbing soft robot.Publicationtype: Conference Paper148 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , On-board pneumatic pressure generation methods for soft robotics applicationsThe design and construction of a soft robot are challenging tasks on their own. When the robot is supposed to operate without a tether, it becomes even more demanding. While a tethered operation is sufficient for a stationary use, it is impractical for wearable robots or performing tasks that demand a high mobility. Choosing and implementing an on-board pneumatic pressure source are particularly complex tasks. There are several different pressure generation methods to choose from, each with very different properties and ways of implementation. This review paper is written with the intention of informing about all pressure generation methods available in the field of soft robotics and providing an overview of the abilities and properties of each method. Nine different methods are described regarding their working principle, pressure generation behavior, energetic considerations, safety aspects, and suitability for soft robotics applications. All presented methods are evaluated in the most important categories for soft robotics pressure sources and compared to each other qualitatively and quantitatively as far as possible. The aim of the results presented is to simplify the choice of a suitable pressure generation method when designing an on-board pressure source for a soft robot.Publicationtype: Journal ArticleScopus© Citations 25 374 438 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Performance of an IMU-Based Sensor Concept for Solving the Direct Kinematics Problem of the Stewart-Gough Platform(2018-12-27); ; The direct kinematics problem of the Stewart-Gough platform can be solved by measuring the manipulator platform's orientation and two of the linear actuators' orientations instead of the six linear actuators' lengths. In this paper, the effect of measurement errors on the calculated manipulator platform's pose is investigated using the Cramer-Ran lower bound and extensive experiments on a state-of-the-art Stewart-Gough platform. Furthermore, different algorithms and filters for one-time as well as continuous pose determinations are investigated. Finally, possible sensor fusion concepts for the one-time pose determination are presented to increase the robustness against noise and measurement errors.Publicationtype: Conference Paper138 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Friction-induced vibrations during tightening of bolted joints : analytical and experimental results(Multidisciplinary Digital Publishing Institute (MDPI), 2018-12-05); ; Bolted joints are one of the most used machine elements. Holding together structures of all sizes, the integrity rests on their shoulders. Thus, an accurate and reliable assembly of the joint is crucial. While it is the aim to not experience friction-induced vibrations at all, at some situations, it is unavoidable. These cases, however, have yet been out of the focus of control algorithms due to the volatile nature of the process. This contribution delivers analytical and experimental results for the occurrence of friction-induced vibrations during tightening of bolted joints. Previous findings of system characteristic constants could be validated, which can be used to monitor the tightening process even while strong vibrations during the tightening process occur. Additionally, a real-time algorithm is presented which allows for an advanced process monitoring and control by identifying process characteristics based on which predictions of the process can be made. These measures significantly improve the capabilities to reach the target values of the tightening process.Publicationtype: Journal Article281 366