Pierre Cherelle

Lock Your Robot: A Review of Locking Devices in Robotics

Locking devices are widely used in robotics, for instance to lock springs and joints or to reconfigure robots. This review article classifies the locking devices currently described in the literature and performs a comparative study. Designers can therefore better determine which locking device best matches the needs of their application. The locking devices are divided into three main categories based on different locking principles: 1) mechanical locking, 2) friction-based locking, and 3) singularity locking. Different locking devices in each category can be passive or active. Based on an extensive literature survey, this article summarizes the findings by comparing different locking devices on a set of properties of an ideal locking device.

Advances in Propulsive Bionic Feet and Their Actuation Principles

In the past decades, researchers have deeply studied pathological and nonpathological gait to understand the human ankle function during walking. These efforts resulted in the development of new lower limb prosthetic devices aiming at raising the 3C-level (control, comfort, and cosmetics) of amputees. Thanks to the technological advances in engineering and mechatronics, challenges in the field of prosthetics have become an important source of interest for roboticists. Currently, most of the bionic feet are still on a research level but show promising results and a preview of tomorrows commercial prosthetic devices. In this paper, the authors present the current state-of-the-art and the latest advances in propulsive bionic feet with its actuation principles. The context of this review study is outlined followed by a brief description of the basics in human biomechanics and criteria for new prosthetic designs. A new categorization based on the actuation principle of propulsive ankle-foot prostheses is proposed. Based on simulations, the general principles and benefits of each actuation method are explained. The corresponding latest advances in propulsive bionic feet are presented together with their main characteristics and scientific outcomes. The authors also propose to the reader a comparison analysis of the presented devices with a discussion of the general tendencies in new prosthetic feet.

A proof-of-concept exoskeleton for robot-assisted rehabilitation of gait

Robotic gait rehabilitation faces many challenges regarding ankle assistance, body weight support and physical human-robot interaction. This paper reports on the development of a gait rehabilitation exoskeleton prototype intended as a platform for the evaluation of design and control concepts in view of improved physical human-robot interaction. The performance of proxy-based sliding mode control as a “robot-in-charge” control strategy is evaluat both in simulation and in experiments on a test setup. Compared to PID control, test results indicate good tracking performance and in particular safe system behavior.

Case Study on Human Walking during Wearing a Powered Prosthetic Device: Effectiveness of the System “Human-Robot”

It is known that force exchanges between a robotic assistive device and the end-user have a direct impact on the quality and performance of a particular movement task. This knowledge finds a special reflective importance in prosthetic industry due to the close human-robot collaboration. Although lower-extremity prostheses are currently better able to provide assistance as their upper-extremity counterparts, specific locomotion problems still remain. In a framework of this contribution the authors introduce the multibody dynamic modelling approach of the transtibial prosthesis wearing on a human body model. The obtained results are based on multibody dynamic simulations against the real experimental data using AMP-Foot 2.0, an energy efficient powered transtibial prosthesis for actively assisted walking of amputees.

PROPULSION SYSTEM WITH PNEUMATIC ARTIFICIAL MUSCLES FOR POWERING ANKLE-FOOT ORTHOSIS

Abstract The aim of this paper is to present the design of device for control of new propulsion system with pneumatic artificial muscles. The propulsion system can be used for ankle joint articulation, for assisting and rehabilitation in cases of injured ankle-foot complex, stroke patients or elderly with functional weakness. Proposed device for control is composed by microcontroller, generator for muscles contractions and sensor system. The microcontroller receives the control signals from sensors and modulates ankle joint flex- ion and extension during human motion. The local joint control with a PID (Proportional-Integral Derivative) position feedback directly calculates desired pressure levels and dictates the necessary contractions. The main goal is to achieve an adaptation of the system and provide the necessary joint torque using position control with feedback.

Biarticular elements as a contributor to energy efficiency: biomechanical review and application in bio-inspired robotics

Despite the increased interest in exoskeleton research in the last decades, not much progress has been made on the successful reduction of user effort. In humans, biarticular elements have been identified as one of the reasons for the energy economy of locomotion. This document gives an extensive literature overview concerning the function of biarticular muscles in human beings. The exact role of these muscles in the efficiency of human locomotion is reduced to three elementary functions: energy transfer towards distal joints, efficient control of output force direction and double joint actuation. This information is used to give an insight in the application of biarticular elements in bio-inspired robotics, i.e. bipedal robots, exoskeletons, robotic manipulators and prostheses. Additionally, an attempt is made to find an answer on the question whether the biarticular property leads to a unique contribution to energy efficiency of locomotion, unachievable by mono-articular alternatives. This knowledge is then further utilised to indicate how biarticular actuation of exoskeletons can contribute to an increased performance in reducing user effort.

Use of Compliant Actuators in Prosthetic Feet and the Design of the AMP-Foot 2.0

From robotic prostheses, to automated gait trainers, rehabilitation robots have one thing in common: they need actuation. The use of compliant actuators is currently growing in importance and has applications in a variety of robotic technologies where accurate trajectory tracking is not required like assistive technology or rehabilitation training. In this chapter, the authors presents the current state-ofthe- art in trans-tibial (TT) prosthetic devices using compliant actuation. After that, a detailed description is given of a new energy efficient below-knee prosthesis, the AMP-Foot 2.0.

Safe and compliant guidance in robot-assisted gait rehabilitation using Proxy-based Sliding Mode Control

Research in robot-assisted gait rehabilitation has seen significant improvements in human-robot interaction, thanks to high performance actuator technologies and dedicated control strategies. In this context we propose a combination of lightweight, intrinsically compliant, high power actuators (Pleated Pneumatic Artificial Muscles, PPAMs) with safe and adaptable guidance along a trajectory by means of Proxy-based Sliding Mode Control (PSMC). Treadmill walking experiments performed by a healthy subject wearing a powered knee exoskeleton indicate two main challenges: synchronizing the compliant device and the subject, and tuning the control parameters in view of safe guidance. The exoskeleton is able to compliantly guide the test persons knee along various target trajectories, while ensuring a smooth response to large perturbations.

ED-FNN: A New Deep Learning Algorithm to Detect Percentage of the Gait Cycle for Powered Prostheses

Throughout the last decade, a whole new generation of powered transtibial prostheses and exoskeletons has been developed. However, these technologies are limited by a gait phase detection which controls the wearable device as a function of the activities of the wearer. Consequently, gait phase detection is considered to be of great importance, as achieving high detection accuracy will produce a more precise, stable, and safe rehabilitation device. In this paper, we propose a novel gait percent detection algorithm that can predict a full gait cycle discretised within a 1% interval. We called this algorithm an exponentially delayed fully connected neural network (ED-FNN). A dataset was obtained from seven healthy subjects that performed daily walking activities on the flat ground and a 15-degree slope. The signals were taken from only one inertial measurement unit (IMU) attached to the lower shank. The dataset was divided into training and validation datasets for every subject, and the mean square error (MSE) error between the model prediction and the real percentage of the gait was computed. An average MSE of 0.00522 was obtained for every subject in both training and validation sets, and an average MSE of 0.006 for the training set and 0.0116 for the validation set was obtained when combining all subjects’ signals together. Although our experiments were conducted in an offline setting, due to the forecasting capabilities of the ED-FNN, our system provides an opportunity to eliminate detection delays for real-time applications.

The efficacy of the Ankle Mimicking Prosthetic Foot prototype 4.0 during walking: Physiological determinants

Background: Evaluating the effectiveness of a novel prosthetic device during walking is an important step in product development. Objective: To investigate the efficacy of a novel quasi-passive ankle prosthetic device, Ankle Mimicking Prosthetic Foot 4.0, during walking at different speeds, using physiological determinants in transtibial and transfemoral amputees. Study design: Nonrandomized crossover design for amputees. Methods: Six able-bodied subjects, six unilateral transtibial amputees, and six unilateral transfemoral amputees underwent a 6-min walk test at normal speed, followed by series of 2-min walking at slow, normal, and fast speeds. The intensity of effort and subjective measures were determined. Amputees performed all walking tests on a treadmill with current and novel prostheses. Shapiro–Wilk normality tests and parametric and nonparametric tests were conducted (p < 0.05). Results: Compared to able-bodied individuals, the rating of perceived exertion levels were significantly elevated in transtibial and transfemoral amputees for both prostheses (p ≤ 0.016). Compared to able-bodied individuals transfemoral amputees also showed significantly elevated heart rate for both prostheses at normal speed (p ≤ 0.043). Within-group comparisons demonstrated that walking with Ankle Mimicking Prosthetic Foot significantly increased the heart rate in transfemoral amputees and transtibial compared to current prosthesis (p = 0.002). Furthermore, transfemoral amputees reached a significantly higher rating of perceived exertion levels. Conclusion: Intensity of effort during walking with Ankle Mimicking Prosthetic Foot is higher compared to current prostheses. Clinical relevance Ankle Mimicking Prosthetic Foot 4.0 is a novel quasi-passive ankle prosthesis with state-of-the-art technological parts. Subjective measures show the importance of this technology, but the intensity of effort during walking still remains higher compared to current passive prostheses, especially in transfemoral amputees.