Towards Design Guidelines for Physical Interfaces on Industrial Exoskeletons: Overview on Evaluation Metrics

Sposito, Matteo; Toxiri, Stefano; Caldwell, Darwin G.; Momi, Elena De

doi:10.1007/978-3-030-01887-0_33

Cited by 16 publications

(17 citation statements)

References 7 publications

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“…Additionally, load cells cannot be used when the interaction between the user’s limb and the robot link is not mediated by a finite number of attachments, but by a distributed area. Pressure distribution can be useful, being directly related with the safety and comfort felt by the user during the robot operation [ 6 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

Integration of 3D Printed Flexible Pressure Sensors into Physical Interfaces for Wearable Robots

Langlois

Roels

Velde

et al. 2021

Sensors

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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.

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Section: Introductionmentioning

confidence: 99%

Integration of 3D Printed Flexible Pressure Sensors into Physical Interfaces for Wearable Robots

Langlois

Roels

Velde

et al. 2021

Sensors

View full text Add to dashboard Cite

show abstract

“…However, a number of implementation barriers remain. In addition to ongoing developments in the fields of actuation and mechanical design (Calabrò et al, 2016;Sposito et al, 2019), there are still limited solutions available for recognizing the user's intent for movement and using it as a control input (Herr, 2009;Calabrò et al, 2016). Moreover, rehabilitation robots are not able to perfectly mimic the movements of the human body.…”

Section: Implementation Barriersmentioning

confidence: 99%

Safety Assessment of Rehabilitation Robots: A Review Identifying Safety Skills and Current Knowledge Gaps

et al. 2021

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The assessment of rehabilitation robot safety is a vital aspect of the development process, which is often experienced as difficult. There are gaps in best practices and knowledge to ensure safe usage of rehabilitation robots. Currently, safety is commonly assessed by monitoring adverse events occurrence. The aim of this article is to explore how safety of rehabilitation robots can be assessed early in the development phase, before they are used with patients. We are suggesting a uniform approach for safety validation of robots closely interacting with humans, based on safety skills and validation protocols. Safety skills are an abstract representation of the ability of a robot to reduce a specific risk or deal with a specific hazard. They can be implemented in various ways, depending on the application requirements, which enables the use of a single safety skill across a wide range of applications and domains. Safety validation protocols have been developed that correspond to these skills and consider domain-specific conditions. This gives robot users and developers concise testing procedures to prove the mechanical safety of their robotic system, even when the applications are in domains with a lack of standards and best practices such as the healthcare domain. Based on knowledge about adverse events occurring in rehabilitation robot use, we identified multi-directional excessive forces on the soft tissue level and musculoskeletal level as most relevant hazards for rehabilitation robots and related them to four safety skills, providing a concrete starting point for safety assessment of rehabilitation robots. We further identified a number of gaps which need to be addressed in the future to pave the way for more comprehensive guidelines for rehabilitation robot safety assessments. Predominantly, besides new developments of safety by design features, there is a strong need for reliable measurement methods as well as acceptable limit values for human-robot interaction forces both on skin and joint level.

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“…In addition, the prototype is expandable to additional flexible capsules with multiple pressure sensors. This may be useful, as apart from magnitude and duration, the pressure distribution is of special interest for human interfaces, which is caused by changes in human soft tissue or mismatches of exoskeletal and human axes [11], [14], [16]. In addition, the force magnitude may be solely assessable via power curves of the exoskeleton actuation or simulated human models.…”

Section: Interface Prototype With Embedded Pressure Sensorsmentioning

confidence: 99%

Towards Embedded Force Sensors in Exoskeletons for Evaluating Interaction Forces in Interfaces

Hoffmann

Ersoysal

Weidner

2020

Annals of Scientific Society for Assembly, Handling and Industrial Robotics

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The applicability of exoskeletons in different daily and occupational settings is continually increasing. Due to varying tasks and user groups, the adaptability of exoskeletons is becoming more significant, with increasing demands for smarter devices. The implementation of force sensors in exoskeletal interfaces could be an approach for analyzing the human-machine interaction in terms of, e.g., wearing comfort, support, and motion synchronicity, as well as optimizing this interaction in real time based on the analyzed sensory data. For this, force sensors need to be embedded in interfaces, which implies the consideration of inexpensive sensors to minimize the total purchase price. However, measuring contact forces on the wearer is challenging and inexpensive flexible force sensing resistors have limited accuracy, repeatability, and stability. This paper evaluates the suitability of an interface principle working with two water capsules and two embedded piezo-resistive pressure sensors in different test scenarios derived from real exoskeletal application examples. Finally, a comparison of the capsules' inner pressures reliably detects different load conditions on the interface such as centered, edged, and shear forces. Thus, this principle seems to be suitable for further exoskeletal considerations.

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Towards Design Guidelines for Physical Interfaces on Industrial Exoskeletons: Overview on Evaluation Metrics

Cited by 16 publications

References 7 publications

Integration of 3D Printed Flexible Pressure Sensors into Physical Interfaces for Wearable Robots

Integration of 3D Printed Flexible Pressure Sensors into Physical Interfaces for Wearable Robots

Safety Assessment of Rehabilitation Robots: A Review Identifying Safety Skills and Current Knowledge Gaps

Towards Embedded Force Sensors in Exoskeletons for Evaluating Interaction Forces in Interfaces

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