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Sensing pressure at the physical interface between the robot and the human has important implications for wearable robots. On the one hand, monitoring pressure distribution can give valuable benefits on the aspects of comfortability and safety of such devices. Additionally, on the other hand, they can be used as a rich sensory input to high level interaction controllers. However, a problem is that the commercial availability of this technology is mostly limited to either low-cost solutions with poor performance or expensive options, limiting the possibilities for iterative designs. As an alternative, in this manuscript we present a three-dimensional (3D) printed flexible capacitive pressure sensor that allows seamless integration for wearable robotic applications. The sensors are manufactured using additive manufacturing techniques, which provides benefits in terms of versatility of design and implementation. In this study, a characterization of the 3D printed sensors in a test-bench is presented after which the sensors are integrated in an upper arm interface. A human-in-the-loop calibration of the sensors is then shown, allowing to estimate the external force and pressure distribution that is acting on the upper arm of seven human subjects while performing a dynamic task. The validation of the method is achieved by means of a collaborative robot for precise force interaction measurements. The results indicate that the proposed sensors are a potential solution for further implementation in human–robot interfaces.
Kevin Langlois; Ellen Roels; Gabriël Van De Velde; Cláudia Espadinha; Christopher Van Vlerken; Tom Verstraten; Bram Vanderborght; Dirk Lefeber. Integration of 3D Printed Flexible Pressure Sensors into Physical Interfaces for Wearable Robots. Sensors 2021, 21, 2157 .
AMA StyleKevin Langlois, Ellen Roels, Gabriël Van De Velde, Cláudia Espadinha, Christopher Van Vlerken, Tom Verstraten, Bram Vanderborght, Dirk Lefeber. Integration of 3D Printed Flexible Pressure Sensors into Physical Interfaces for Wearable Robots. Sensors. 2021; 21 (6):2157.
Chicago/Turabian StyleKevin Langlois; Ellen Roels; Gabriël Van De Velde; Cláudia Espadinha; Christopher Van Vlerken; Tom Verstraten; Bram Vanderborght; Dirk Lefeber. 2021. "Integration of 3D Printed Flexible Pressure Sensors into Physical Interfaces for Wearable Robots." Sensors 21, no. 6: 2157.
Physical human-robot interfaces are a challenging aspect of exoskeleton design, mainly due to the fact that interfaces tend to migrate relatively to the body leading to discomfort and power losses. Therefore, the key is to develop interfaces that optimize attachment stiffness, i.e. reduce relative motion, without compromising comfort. To that end, we propose a method to obtain the optimal attachment pressure in terms of connection stiffness and comfort. The method is based on a soft robotic interface capable of actively controlling strapping pressure which is coupled to a cobot. Hereby the effects of strapping pressure on energetic losses, connection stiffness, and perceived comfort are analyzed. Results indicate a trade-off between connection stiffness and perceived comfort for this type of interface. An optimal strapping pressure was found in the 50 to 80 mmHg range. Connection stiffness was found to increase linearly over a pressure range from 0 mmHg (stiffness of 1139 N/m) to 100 mmHg (stiffness of 2232 N/m). And energetic losses were reduced by 42% by increasing connection stiffness. This research highlights the importance of strapping pressure when attaching an exoskeleton to a human and introduces a new adaptive interface to improve the coupling from an exoskeleton to an individual.
Kevin Langlois; David Rodriguez-Cianca; Ben Serrien; Joris De Winter; Tom Verstraten; Carlos Rodriguez-Guerrero; Bram Vanderborght; Dirk Lefeber. Investigating the Effects of Strapping Pressure on Human-Robot Interface Dynamics Using a Soft Robotic Cuff. IEEE Transactions on Medical Robotics and Bionics 2020, 3, 146 -155.
AMA StyleKevin Langlois, David Rodriguez-Cianca, Ben Serrien, Joris De Winter, Tom Verstraten, Carlos Rodriguez-Guerrero, Bram Vanderborght, Dirk Lefeber. Investigating the Effects of Strapping Pressure on Human-Robot Interface Dynamics Using a Soft Robotic Cuff. IEEE Transactions on Medical Robotics and Bionics. 2020; 3 (1):146-155.
Chicago/Turabian StyleKevin Langlois; David Rodriguez-Cianca; Ben Serrien; Joris De Winter; Tom Verstraten; Carlos Rodriguez-Guerrero; Bram Vanderborght; Dirk Lefeber. 2020. "Investigating the Effects of Strapping Pressure on Human-Robot Interface Dynamics Using a Soft Robotic Cuff." IEEE Transactions on Medical Robotics and Bionics 3, no. 1: 146-155.
Fast and accurate gait phase detection is essential to achieve effective powered lower-limb prostheses and exoskeletons. As the versatility but also the complexity of these robotic devices increases, the research on how to make gait detection algorithms more performant and their sensing devices smaller and more wearable gains interest. A functional gait detection algorithm will improve the precision, stability, and safety of prostheses, and other rehabilitation devices. In the past years the state-of-the-art has advanced significantly in terms of sensors, signal processing, and gait detection algorithms. In this review, we investigate studies and developments in the field of gait event detection methods, more precisely applied to prosthetic devices. We compared advantages and limitations between all the proposed methods and extracted the relevant questions and recommendations about gait detection methods for future developments.
Huong Thi Thu Vu; Dianbiao Dong; Hoang-Long Cao; Tom Verstraten; Dirk Lefeber; Bram VanderBorght; Joost Geeroms. A Review of Gait Phase Detection Algorithms for Lower Limb Prostheses. Sensors 2020, 20, 3972 .
AMA StyleHuong Thi Thu Vu, Dianbiao Dong, Hoang-Long Cao, Tom Verstraten, Dirk Lefeber, Bram VanderBorght, Joost Geeroms. A Review of Gait Phase Detection Algorithms for Lower Limb Prostheses. Sensors. 2020; 20 (14):3972.
Chicago/Turabian StyleHuong Thi Thu Vu; Dianbiao Dong; Hoang-Long Cao; Tom Verstraten; Dirk Lefeber; Bram VanderBorght; Joost Geeroms. 2020. "A Review of Gait Phase Detection Algorithms for Lower Limb Prostheses." Sensors 20, no. 14: 3972.
Redundancy facilitates some of the most remarkable capabilities of humans, and is therefore omni-present in our physiology. The relationship between redundancy in robotics and biology is investigated in detail on the Series Elastic Dual-Motor Actuator (SEDMA), an actuator inspired by the kinematic redundancy exhibited by myofibrils. The actuator consists of two motors coupled to a single spring at the output. Such a system has a redundant degree of freedom, which can be exploited to optimize aspects such as accuracy, impedance, fault-tolerance and energy efficiency. To test its potential for human-like motions, the SEDMA actuator is implemented in a hopping robot. Experiments on a physical demonstrator show that the robot’s movement patterns resemble human squat jumps. We conclude that robots with bio-inspired actuator designs facilitate human-like movement, although current technical limitations may prevent them from reaching the same dynamic and energetic performance.
Tom Verstraten; Christian Schumacher; Raphaël Furnémont; Andre Seyfarth; Philipp Beckerle. Redundancy in Biology and Robotics: Potential of Kinematic Redundancy and its Interplay with Elasticity. Journal of Bionic Engineering 2020, 17, 695 -707.
AMA StyleTom Verstraten, Christian Schumacher, Raphaël Furnémont, Andre Seyfarth, Philipp Beckerle. Redundancy in Biology and Robotics: Potential of Kinematic Redundancy and its Interplay with Elasticity. Journal of Bionic Engineering. 2020; 17 (4):695-707.
Chicago/Turabian StyleTom Verstraten; Christian Schumacher; Raphaël Furnémont; Andre Seyfarth; Philipp Beckerle. 2020. "Redundancy in Biology and Robotics: Potential of Kinematic Redundancy and its Interplay with Elasticity." Journal of Bionic Engineering 17, no. 4: 695-707.
Diabetes mellitus (DM) is a highly prevalent, chronic condition in adults worldwide. Little is known about the potential role of diabetes as an effect modifier of vaccine protective responses. We conducted a literature review of the immunogenicity, efficacy and effectiveness of immunization in individuals, in studies that compared subjects with DM (DM+) and without DM (DM-). We found few published studies, which were only for vaccines against hepatitis B, influenza, pneumococcal disease, or varicela zoster. Except for a consistent attenuation of the immune response to hepatitis B vaccine among DM+ individuals, we found little other consistent evidence for DM as an effect modifier of vaccine responses. There are substantial gaps in our knowledge of the impact of DM on the immune response to immunization or effect of vaccination.
Thomas Verstraeten; Mark A. Fletcher; Jose A. Suaya; Sally Jackson; Cassandra K. Hall-Murray; Daniel A. Scott; Beate Schmöle-Thoma; Raul E. Isturiz; Bradford D. Gessner. Diabetes mellitus as a vaccine-effect modifier: a review. Expert Review of Vaccines 2020, 19, 445 -453.
AMA StyleThomas Verstraeten, Mark A. Fletcher, Jose A. Suaya, Sally Jackson, Cassandra K. Hall-Murray, Daniel A. Scott, Beate Schmöle-Thoma, Raul E. Isturiz, Bradford D. Gessner. Diabetes mellitus as a vaccine-effect modifier: a review. Expert Review of Vaccines. 2020; 19 (5):445-453.
Chicago/Turabian StyleThomas Verstraeten; Mark A. Fletcher; Jose A. Suaya; Sally Jackson; Cassandra K. Hall-Murray; Daniel A. Scott; Beate Schmöle-Thoma; Raul E. Isturiz; Bradford D. Gessner. 2020. "Diabetes mellitus as a vaccine-effect modifier: a review." Expert Review of Vaccines 19, no. 5: 445-453.
In several industrial applications, drivetrains impose highly dynamic oscillating motions to inertial loads. By introducing springs, the system’s natural frequencies can be matched to the required operating frequencies, lowering energy consumption of the drivetrain. However, fixed-stiffness springs only have a positive effect in a limited range of frequencies. To solve this problem, variable stiffness springs are proposed. A discussion of the effect of the series and parallel topology, as well as the possibility of adapting the spatio-temporal characteristics of the motion to the spring, is presented. Furthermore, a practical implementation of a variable stiffness spring is proposed. Its effectiveness is validated in experiments. Communicated by Marat Z. Dosaev.
Tom Verstraten; Pablo López-García; Bert Lenaerts; Branimir Mrak; Dirk Lefeber; Bram VanderBorght. Improving the performance of industrial machines with variable stiffness springs. Mechanics Based Design of Structures and Machines 2020, 1 -20.
AMA StyleTom Verstraten, Pablo López-García, Bert Lenaerts, Branimir Mrak, Dirk Lefeber, Bram VanderBorght. Improving the performance of industrial machines with variable stiffness springs. Mechanics Based Design of Structures and Machines. 2020; ():1-20.
Chicago/Turabian StyleTom Verstraten; Pablo López-García; Bert Lenaerts; Branimir Mrak; Dirk Lefeber; Bram VanderBorght. 2020. "Improving the performance of industrial machines with variable stiffness springs." Mechanics Based Design of Structures and Machines , no. : 1-20.
Dianbiao Dong; Wenjie Ge; Bryan Convens; Yuanxi Sun; Tom Verstraten; Bram VanderBorght. Design, Optimization and Energetic Evaluation of an Efficient Fully Powered Ankle-Foot Prosthesis With a Series Elastic Actuator. IEEE Access 2020, 8, 61491 -61503.
AMA StyleDianbiao Dong, Wenjie Ge, Bryan Convens, Yuanxi Sun, Tom Verstraten, Bram VanderBorght. Design, Optimization and Energetic Evaluation of an Efficient Fully Powered Ankle-Foot Prosthesis With a Series Elastic Actuator. IEEE Access. 2020; 8 ():61491-61503.
Chicago/Turabian StyleDianbiao Dong; Wenjie Ge; Bryan Convens; Yuanxi Sun; Tom Verstraten; Bram VanderBorght. 2020. "Design, Optimization and Energetic Evaluation of an Efficient Fully Powered Ankle-Foot Prosthesis With a Series Elastic Actuator." IEEE Access 8, no. : 61491-61503.
In robotic actuators, low speeds and high torques are usually required. Small electric motors, which are more efficient at high speeds and low torques, do not fit the requirements directly. In order to transform the motor characteristics into the desired output characteristics, a transmission system is needed. Ideally, it should be optimally designed and adapted to the desired characteristics and the available space. Scaling laws can provide a way to design these desired output requirements as a function of the size parameters. These are however not yet available for transmission systems. To fill this gap, several scaling laws are developed throughout this paper for some of the most important robotic characteristics, i.e. maximum continuous output torque and reflected inertia, in function of the number of stages, the transmission ratio and the size parameters of different types of transmissions. These laws show that diameter has a much bigger influence on the characteristics of transmissions than length. All derived laws show good comparison with catalog data of manufacturers like Maxon, Moog, Neugart, Harmonic Drive®, Sumitomo and SKF.
Elias Saerens; Stein Crispel; Pablo López García; Tom Verstraten; Vincent Ducastel; Bram Vanderborght; Dirk Lefeber. Scaling laws for robotic transmissions. Mechanism and Machine Theory 2019, 140, 601 -621.
AMA StyleElias Saerens, Stein Crispel, Pablo López García, Tom Verstraten, Vincent Ducastel, Bram Vanderborght, Dirk Lefeber. Scaling laws for robotic transmissions. Mechanism and Machine Theory. 2019; 140 ():601-621.
Chicago/Turabian StyleElias Saerens; Stein Crispel; Pablo López García; Tom Verstraten; Vincent Ducastel; Bram Vanderborght; Dirk Lefeber. 2019. "Scaling laws for robotic transmissions." Mechanism and Machine Theory 140, no. : 601-621.
The key component in compliant actuators is the elastic element, typically a spring. Nevertheless, different types of springs have different characteristics in terms of size, weight, maximum allowable force, maximum allowable torque and maximum allowable deflection. It is however very important to compare them on these requirements, since each application has other demands. In this paper, the energy storage capacity of different types of compliant elements are calculated using scaling laws in order to easily derive the maximum achievable energy capacity for a certain arrangement. These scaling laws are given as a function of the structural parameters and are validated with catalog data of spring manufacturers and distributors such as Alcomex, Lesjöfors and Century Spring. As such, different types of compliant elements can be compared in an easy way. To fully exploit the capabilities of compliant elements, these scaling laws are used to verify the effect of spring parallelization on mass and/or enclosed volume, which is interesting regarding redundant compliant actuation. From theoretical calculations and a case study, it follows that parallelization is beneficial, especially for mass reduction.
Elias Saerens; Raphaël Furnémont; Tom Verstraten; Pablo López García; Stein Crispel; Vincent Ducastel; Bram Vanderborght; Dirk Lefeber. Scaling laws of compliant elements for high energy storage capacity in robotics. Mechanism and Machine Theory 2019, 139, 482 -505.
AMA StyleElias Saerens, Raphaël Furnémont, Tom Verstraten, Pablo López García, Stein Crispel, Vincent Ducastel, Bram Vanderborght, Dirk Lefeber. Scaling laws of compliant elements for high energy storage capacity in robotics. Mechanism and Machine Theory. 2019; 139 ():482-505.
Chicago/Turabian StyleElias Saerens; Raphaël Furnémont; Tom Verstraten; Pablo López García; Stein Crispel; Vincent Ducastel; Bram Vanderborght; Dirk Lefeber. 2019. "Scaling laws of compliant elements for high energy storage capacity in robotics." Mechanism and Machine Theory 139, no. : 482-505.
This paper presents the conceptual development and validation tests of a novel actuation paradigm for wearable robots, the flexible shaft-driven Remote and Torsionally Compliant Actuator. The RTCA exploits both the torsional compliance and bending properties of a commercial flexible shaft to provide simultaneously the advantages of remote actuation systems: improved weight distribution and reduced inertia on the distal joints, together with the advantages of compliant systems. The flexible shaft can be modelled following the proposed methodology as a torsionally compliant element that can be bent, so that the RTCA's output transmitted torque can be estimated based on the flexible shaft's torsional deflection angle and spatial configuration, allowing accurate torque control at the distal joint following a remote actuation approach based only on position sensors. Torque control and transparency tests were used to validate the proposed torque estimation and control approach. Finally, we presented a realistic implementation approach of the RTCA concept into a test bench resembling a lower limb exoskeleton as a case study for wearable robots. Results confirmed the capabilities of the proposed approach and supported the envisioned advantages of this novel actuation paradigm, constituting a promising solution for future developments in this field.
D. Rodriguez-Cianca; C. Rodriguez-Guerrero; T. Verstraten; R. Jimenez-Fabian; B. VanderBorght; D. Lefeber. A Flexible shaft-driven Remote and Torsionally Compliant Actuator (RTCA) for wearable robots. Mechatronics 2019, 59, 178 -188.
AMA StyleD. Rodriguez-Cianca, C. Rodriguez-Guerrero, T. Verstraten, R. Jimenez-Fabian, B. VanderBorght, D. Lefeber. A Flexible shaft-driven Remote and Torsionally Compliant Actuator (RTCA) for wearable robots. Mechatronics. 2019; 59 ():178-188.
Chicago/Turabian StyleD. Rodriguez-Cianca; C. Rodriguez-Guerrero; T. Verstraten; R. Jimenez-Fabian; B. VanderBorght; D. Lefeber. 2019. "A Flexible shaft-driven Remote and Torsionally Compliant Actuator (RTCA) for wearable robots." Mechatronics 59, no. : 178-188.
The potential areas of application for exoskeletons are expanding as technological advances are made in their realization. Among the technological challenges still unsolved, actuator design affects many important properties of the resulting device, such as weight and user comfort. We consider here the case of an active exoskeleton designed to assist the lower back during lifting tasks. In previous studies, a parallel-elastic actuator was shown to improve torque control bandwidth over a “traditional” stiff actuator in generating the required torque profiles, by enabling lower-inertia designs. This paper reports our results on energy consumption showing that an appropriately designed parallel spring also substantially reduces the electrical energy consumption (by well over 50% in the proposed case), enabling exoskeleton designs with reduced weight and improved power autonomy.
Stefano Toxiri; Tom Verstraten; Andrea Calanca; Darwin G. Caldwell; Jesus Ortiz. Using parallel elasticity in back-support exoskeletons: a study on energy consumption during industrial lifting tasks. 2019 Wearable Robotics Association Conference (WearRAcon) 2019, 1 -6.
AMA StyleStefano Toxiri, Tom Verstraten, Andrea Calanca, Darwin G. Caldwell, Jesus Ortiz. Using parallel elasticity in back-support exoskeletons: a study on energy consumption during industrial lifting tasks. 2019 Wearable Robotics Association Conference (WearRAcon). 2019; ():1-6.
Chicago/Turabian StyleStefano Toxiri; Tom Verstraten; Andrea Calanca; Darwin G. Caldwell; Jesus Ortiz. 2019. "Using parallel elasticity in back-support exoskeletons: a study on energy consumption during industrial lifting tasks." 2019 Wearable Robotics Association Conference (WearRAcon) , no. : 1-6.
Bryan Convens; Dianbiao Dong; Raphael Furnemont; Tom Verstraten; Pierre Cherelle; Dirk Lefeber; Bram VanderBorght. Modeling, Design and Test-Bench Validation of a Semi-Active Propulsive Ankle Prosthesis With a Clutched Series Elastic Actuator. IEEE Robotics and Automation Letters 2019, 4, 1823 -1830.
AMA StyleBryan Convens, Dianbiao Dong, Raphael Furnemont, Tom Verstraten, Pierre Cherelle, Dirk Lefeber, Bram VanderBorght. Modeling, Design and Test-Bench Validation of a Semi-Active Propulsive Ankle Prosthesis With a Clutched Series Elastic Actuator. IEEE Robotics and Automation Letters. 2019; 4 (2):1823-1830.
Chicago/Turabian StyleBryan Convens; Dianbiao Dong; Raphael Furnemont; Tom Verstraten; Pierre Cherelle; Dirk Lefeber; Bram VanderBorght. 2019. "Modeling, Design and Test-Bench Validation of a Semi-Active Propulsive Ankle Prosthesis With a Clutched Series Elastic Actuator." IEEE Robotics and Automation Letters 4, no. 2: 1823-1830.
Robots often switch from highly dynamic motion to delivering high torques at low speeds. The actuation requirements for these two regimes are very different. As a consequence, the average efficiency of the actuators is typically much lower than the efficiency at the optimal working point. A potential solution is to use multiple motors for a single motor joint. This results in a redundant degree of freedom, which can be exploited to make the system more efficient overall. In this work, we explore the potential of kinematically redundant actuators in dynamic applications. The potential of a kinematically redundant actuator with two motors is evaluated against a single-motor equivalent in terms of operating range, maximum acceleration, and energy consumption. We discuss how the comparison is influenced by the design of the actuator and the way how the power is distributed over the input motors. Our results support the idea that kinematically redundant actuators can resolve the conflicting torque–speed requirements typical of robots.
Tom Verstraten; Raphael Furnémont; Pablo López-García; David Rodriguez-Cianca; Bram VanderBorght; Dirk Lefeber. Kinematically redundant actuators, a solution for conflicting torque–speed requirements. The International Journal of Robotics Research 2019, 38, 612 -629.
AMA StyleTom Verstraten, Raphael Furnémont, Pablo López-García, David Rodriguez-Cianca, Bram VanderBorght, Dirk Lefeber. Kinematically redundant actuators, a solution for conflicting torque–speed requirements. The International Journal of Robotics Research. 2019; 38 (5):612-629.
Chicago/Turabian StyleTom Verstraten; Raphael Furnémont; Pablo López-García; David Rodriguez-Cianca; Bram VanderBorght; Dirk Lefeber. 2019. "Kinematically redundant actuators, a solution for conflicting torque–speed requirements." The International Journal of Robotics Research 38, no. 5: 612-629.
Series Elastic Actuators (SEAs) are used extensively in the field of wearable robotics because of their energy efficiency. Redundant drivetrains enable a further reduction in electrical energy consumption, as they use the actuator’s motors in a more energy efficient way. In this work, we present a Series Elastic Dual-Motor Actuator (SEDMA), a kinematically redundant actuator with series elasticity. We simulate its use in an ankle prosthesis and compare its energy efficiency to that of a traditional SEA. Results indicate an energy reduction of 16% compared to the SEA.
Tom Verstraten; Raphaël Furnémont; Pablo López-García; Stein Crispel; Bram VanderBorght; Dirk Lefeber. A Series Elastic Dual-Motor Actuator Concept for Wearable Robotics. Converging Clinical and Engineering Research on Neurorehabilitation 2018, 165 -169.
AMA StyleTom Verstraten, Raphaël Furnémont, Pablo López-García, Stein Crispel, Bram VanderBorght, Dirk Lefeber. A Series Elastic Dual-Motor Actuator Concept for Wearable Robotics. Converging Clinical and Engineering Research on Neurorehabilitation. 2018; ():165-169.
Chicago/Turabian StyleTom Verstraten; Raphaël Furnémont; Pablo López-García; Stein Crispel; Bram VanderBorght; Dirk Lefeber. 2018. "A Series Elastic Dual-Motor Actuator Concept for Wearable Robotics." Converging Clinical and Engineering Research on Neurorehabilitation , no. : 165-169.
Conducting an FMEA for the design of a planetary gear transmission for exoskeletons enables decision making based on the interdependence between design parameters and the device requirements, as well as an early identification of several functional risks. Therefore, the use of FMEAs in the design of wearable robotic devices could contribute to higher design robustness, and ultimately result in a broader acceptance of future active wearable robotic devices.
Pablo Lopez Garcia; Stein Crispel; Tom Verstraten; Elias Saerens; Bryan Convens; Bram VanderBorght; Dirk Lefeber. Failure Mode and Effect Analysis (FMEA)-Driven Design of a Planetary Gearbox for Active Wearable Robotics. Converging Clinical and Engineering Research on Neurorehabilitation 2018, 460 -464.
AMA StylePablo Lopez Garcia, Stein Crispel, Tom Verstraten, Elias Saerens, Bryan Convens, Bram VanderBorght, Dirk Lefeber. Failure Mode and Effect Analysis (FMEA)-Driven Design of a Planetary Gearbox for Active Wearable Robotics. Converging Clinical and Engineering Research on Neurorehabilitation. 2018; ():460-464.
Chicago/Turabian StylePablo Lopez Garcia; Stein Crispel; Tom Verstraten; Elias Saerens; Bryan Convens; Bram VanderBorght; Dirk Lefeber. 2018. "Failure Mode and Effect Analysis (FMEA)-Driven Design of a Planetary Gearbox for Active Wearable Robotics." Converging Clinical and Engineering Research on Neurorehabilitation , no. : 460-464.
In the field of wearable robots, high power density and highly efficient actuators are required to handle the high-power motion without becoming heavy and bulky and hence hamper their mobility. Typically, electrical motors are used in combination with high gear ratio gearheads or lever arms in order to achieve the required torques. These gearboxes consist mainly out of several stages of simple Planetary Gear Trains (PGTs). However, this approach leads to big and heavy gearboxes when high torque is needed. An alternative, more compact, design to obtain the required torque increase can be achieved using Compound Planetary Gears (C-PGTs). It is shown that the latter mechanism can obtain gear ratios up to 1:600 while withstanding an output torque of 100 Nm.
Stein Crispel; Pablo López García; Tom Verstraten; Bryan Convens; Elias Saerens; Bram VanderBorght; Dirk Lefeber. Introducing Compound Planetary Gears (C-PGTs): A Compact Way to Achieve High Gear Ratios for Wearable Robots. Converging Clinical and Engineering Research on Neurorehabilitation 2018, 485 -489.
AMA StyleStein Crispel, Pablo López García, Tom Verstraten, Bryan Convens, Elias Saerens, Bram VanderBorght, Dirk Lefeber. Introducing Compound Planetary Gears (C-PGTs): A Compact Way to Achieve High Gear Ratios for Wearable Robots. Converging Clinical and Engineering Research on Neurorehabilitation. 2018; ():485-489.
Chicago/Turabian StyleStein Crispel; Pablo López García; Tom Verstraten; Bryan Convens; Elias Saerens; Bram VanderBorght; Dirk Lefeber. 2018. "Introducing Compound Planetary Gears (C-PGTs): A Compact Way to Achieve High Gear Ratios for Wearable Robots." Converging Clinical and Engineering Research on Neurorehabilitation , no. : 485-489.
In the last two decades, numerous powered ankle-foot orthoses have been developed. Despite similar designs and control strategies being shared by some of these devices, their performance in terms of achieving a comparable goal varies. It has been shown that the effect of powered ankle-foot orthoses on healthy users is altered by some factors of the testing protocol. This paper provides an overview of the effect of powered walking on healthy and weakened users. It identifies a set of key factors influencing the performance of powered ankle-foot orthoses, and it presents the effects of these factors on healthy subjects, highlighting the similarities and differences of the results obtained in different works. Furthermore, the outcomes of studies performed on elderly and impaired subjects walking with powered ankle-foot orthoses are compared, to outline the effects of powered walking on these users. This article shows that several factors mutually influence the performance of powered ankle-foot orthoses on their users and, for this reason, the determination of their effects on the user is not straightforward. One of the key factors is the adaptation of users to provided assistance. This factor is very important for the assessment of the effects of powered ankle-foot orthoses on users, however, it is not always reported by studies. Moreover, future works should report, together with the results, the list of influencing factors used in the protocol, to facilitate the comparison of the obtained results. This article also underlines the need for a standardized method to benchmark the actuators of powered ankle-foot orthoses, which would ease the comparison of results between the performed studies. In this paper, the lack of studies on elderly and impaired subjects is highlighted. The insufficiency of these studies makes it difficult to assess the effects of powered ankle-foot orthoses on these users.To summarize, this article provides a detailed overview of the work performed on powered ankle-foot orthoses, presenting and analyzing the results obtained, but also emphasizing topics on which more research is still required.
Marta Moltedo; Tomislav Baček; Tom Verstraten; Carlos Rodriguez-Guerrero; Bram VanderBorght; Dirk Lefeber. Powered ankle-foot orthoses: the effects of the assistance on healthy and impaired users while walking. Journal of NeuroEngineering and Rehabilitation 2018, 15, 86 .
AMA StyleMarta Moltedo, Tomislav Baček, Tom Verstraten, Carlos Rodriguez-Guerrero, Bram VanderBorght, Dirk Lefeber. Powered ankle-foot orthoses: the effects of the assistance on healthy and impaired users while walking. Journal of NeuroEngineering and Rehabilitation. 2018; 15 (1):86.
Chicago/Turabian StyleMarta Moltedo; Tomislav Baček; Tom Verstraten; Carlos Rodriguez-Guerrero; Bram VanderBorght; Dirk Lefeber. 2018. "Powered ankle-foot orthoses: the effects of the assistance on healthy and impaired users while walking." Journal of NeuroEngineering and Rehabilitation 15, no. 1: 86.
We developed a new actuator, the plus Series-Parallel Elastic Actuator (+SPEA), which is a redundant actuator using brakes. This actuator can achieve additional objectives, other than performing a given task, such as minimum electrical energy consumption. In this paper, we developed a novel control strategy which consists of solving an optimal control problem. Solving this problem allows to use the redundancy of the actuator, as the brakes, in order to achieve lower electrical consumption. The results are then compared to the consumption of an equivalent non-redundant stiff actuator. The results highlight the capability of the actuator to reduce energy consumption in comparison with the latter actuator.
Raphaël Furnémont; Glenn Mathijssen; Tom Verstraten; Rene Jimenez-Fabian; Dirk Lefeber; Bram Vanderborght. Novel control strategy for the +SPEA: A redundant actuator with reconfigurable parallel elements. Mechatronics 2018, 53, 28 -38.
AMA StyleRaphaël Furnémont, Glenn Mathijssen, Tom Verstraten, Rene Jimenez-Fabian, Dirk Lefeber, Bram Vanderborght. Novel control strategy for the +SPEA: A redundant actuator with reconfigurable parallel elements. Mechatronics. 2018; 53 ():28-38.
Chicago/Turabian StyleRaphaël Furnémont; Glenn Mathijssen; Tom Verstraten; Rene Jimenez-Fabian; Dirk Lefeber; Bram Vanderborght. 2018. "Novel control strategy for the +SPEA: A redundant actuator with reconfigurable parallel elements." Mechatronics 53, no. : 28-38.
With series and parallel elastic elements, considerable reductions in the mechanical peak power and energy consumption of active ankle prostheses can be obtained. Very few works, however, evaluate the electrical energy consumption of these devices. In this work, we analyze and discuss the differences between the mechanical and electrical energy consumption of these actuators. Design optimizations based on mechanical and electrical energy consumption are compared for a series elastic actuator, parallel elastic actuator and series elastic actuator with unidirectional spring. The results are then analyzed by means of torque-angle plots, power flow graphs and motor efficiency maps. The analysis highlights the impact of drivetrain inertia on the peak power and energy efficiency of the system. Moreover, interaction between the series spring and unidirectional parallel spring is identified as a potential cause of reduced actuator bandwidth. A parallel elastic actuator is found to be the most compact and energy-efficient solution overall as it makes the most efficient use of the electric motor.
Tom Verstraten; Louis Flynn; Joost Geeroms; Bram VanderBorght; Dirk Lefeber. On the Electrical Energy Consumption of Active Ankle Prostheses with Series and Parallel Elastic Elements. 2018 7th IEEE International Conference on Biomedical Robotics and Biomechatronics (Biorob) 2018, 720 -725.
AMA StyleTom Verstraten, Louis Flynn, Joost Geeroms, Bram VanderBorght, Dirk Lefeber. On the Electrical Energy Consumption of Active Ankle Prostheses with Series and Parallel Elastic Elements. 2018 7th IEEE International Conference on Biomedical Robotics and Biomechatronics (Biorob). 2018; ():720-725.
Chicago/Turabian StyleTom Verstraten; Louis Flynn; Joost Geeroms; Bram VanderBorght; Dirk Lefeber. 2018. "On the Electrical Energy Consumption of Active Ankle Prostheses with Series and Parallel Elastic Elements." 2018 7th IEEE International Conference on Biomedical Robotics and Biomechatronics (Biorob) , no. : 720-725.
By connecting two drivetrains to a single load, a redundant degree of freedom is created. In this work, we investigate how the redundancy of such a system can be exploited in order to make it more energy efficient. The system under study consists of two drivetrains coupled to a planetary differential. Both drivetrains are composed of a geared DC motor and a holding brake. First, we derive an accurate semi-empirical model of this system and prove its validity on a test setup. Based on this model, which includes nonlinear friction terms, we analyze how the power flows and energy losses depend on the redundant degree of freedom. Furthermore, we discuss how the design of the actuator can be optimized for energy efficiency. This strategy is applied to a case study, where a 250 W geared DC motor is replaced by a more efficient dual-motor actuator. Experiments confirm that a dual-motor actuator succeeds in reducing the energy consumption at various loads and speeds. We also show that the results are very sensitive to friction and other speed- and load-dependent losses.
Tom Verstraten; Raphaël Furnémont; Pablo Lopez Garcia; David Rodriguez-Cianca; Hoang-Long Cao; Bram Vanderborght; Dirk Lefeber. Modeling and design of an energy-efficient dual-motor actuation unit with a planetary differential and holding brakes. Mechatronics 2017, 49, 134 -148.
AMA StyleTom Verstraten, Raphaël Furnémont, Pablo Lopez Garcia, David Rodriguez-Cianca, Hoang-Long Cao, Bram Vanderborght, Dirk Lefeber. Modeling and design of an energy-efficient dual-motor actuation unit with a planetary differential and holding brakes. Mechatronics. 2017; 49 ():134-148.
Chicago/Turabian StyleTom Verstraten; Raphaël Furnémont; Pablo Lopez Garcia; David Rodriguez-Cianca; Hoang-Long Cao; Bram Vanderborght; Dirk Lefeber. 2017. "Modeling and design of an energy-efficient dual-motor actuation unit with a planetary differential and holding brakes." Mechatronics 49, no. : 134-148.