• ROBOTICS 21XX

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  • Soft wearable robots that use innovative textiles to provide a more conformal, unobtrusive and compliant means to interface to the human body. These robots will augment the capabilities of healthy individuals (e.g. improved walking efficiency) in addition to assisting those with muscle weakness or patients who suffer from physical or neurological disorders.
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  • Harvard Biodesign Lab

      • Soft Exosuits

      • We are developing next generation soft wearable robots that use innovative textiles to provide a more conformal, unobtrusive and compliant means to interface to the human body. These robots will augment the capabilities of healthy individuals (e.g. improved walking efficiency) in addition to assisting those with muscle weakness or patients who suffer from physical or neurological disorders. As compared to a traditional exoskeleton, these systems have several advantages: the wearer's joints are unconstrained by external rigid structures, and the worn part of the suit is extremely light. These properties minimize the suit's unintentional interference with the body's natural biomechanics and allow for more synergistic interaction with the wearer.
          • Structured functional textiles

          • We are creating innovative textiles that are inspired by an understanding of human biomechanics and anatomy. These wearable garments provide means to transmit assistive torques to a wearer’s joints without the use of rigid external structures. In order to obtain high-performance soft exosuits, some considerations should be taken into account in the design process. Exosuits should attach to the body securely and comfortably, and transmit forces over the body through beneficial paths such that biologically-appropriate moments are created at the joints. In addition, these garments can be designed to passively (with no active power) generate assistive forces due to the natural movement of the wear for particular tasks. A key feature of exosuits is that if the actuated segments are extended, the suit length can increase so that the entire suit is slack, at which point wearing an exosuit feels like wearing a pair of pants and does not restrict the wearer whatsoever.
          • Lightweight and efficient actuation

          • In order to provide active assistance through the soft interface, we are developing a number of actuation platforms that can apply controlled forces to the wearer by attaching at anchoring points in the wearable garment. We are developing lightweight and fully portable systems and a key feature of our approach is that we minimize the distal mass that is attached to the wearer through more proximally mounted actuation systems and flexible transmissions that transmit power to the joints. While most of our recent work is on cable-driven electromechanical approaches, we have also pursued pneumatic based approaches. This early work with McKibbon actuators in 2013 was the first demonstration that a soft exosuit can have a positive effect on mobility.
          • Wearable sensors

          • New sensor systems that are easy to integrate with textiles and soft components are required in order to properly control and evaluate soft exosuits. Rigid exoskeletons usually include sensors such as encoders or potentiometers in robotic joints that accurately track joint angles, but these technologies are not compatible with soft structures. Our approach is to design new sensors to measure human kinematics and suit-human interaction forces that are robust, compliant, cost effective, and offer easy integration into wearable garments. In addition, we use other off the shelf sensor technologies (e.g. gyro, pressure sensor, IMU) that can be used to detect key events in the gait cycle. These wearable sensors can be used as part of the control strategy for the wearable robot or alternatively to monitor and record the movement of the wearer (when wearing the exosuit or as a standalone sensor suit) for tracking changes over time or determining what activities they are performing (e.g. walking vs running).
          • Intuitive and robust control

          • We are also developing rapidly reconfigurable multi-actuator systems that provide more flexibility for lab-based studies. Such an approach allows us to rapidly explore the basic science around human-machine interaction with such systems that can then be used to guide the design of our portable systems. A robust, intuitive and adaptive human-machine interface is a necessary component for a wearable robot to interact synergistically with the wearer. Our focus is to provide assistance in a manner that does not disrupt the natural, passive dynamics that make walking or running so efficient. To achieve this, we develop approaches to non-invasively estimate the intent so that any actuation applied assists that from the appropriate biological muscles. A key feature of our approach is to leverage integrated sensors that monitor the wearer interaction with the compliant textile that interfaces to the body as well as other sensors that detect key moment during the gait cycle.
          • Experimental biomechanics

          • Our motion capture lab utilizes a Vicon T-series 9-camera system for motion capture, together with a Bertec fully instrumented split-belt treadmill to measure GRFs. By comparing the average profile and range of motion of each joint in the three conditions, we can identify how the soft exosuit itself impacts gait and how the assistance applied by the exosuit changes kinematics. Our hypothesis is that it is desirable that such changes are minimal and in any case not disruptive to natural gait. We study to what extent the active exosuit is assisting the human by analyzing gait dynamics and kinetics (joint moments, power, force delivered by the exosuit). Inverse dynamics is an effective way to determine to what degree the exosuit is augmenting the body function at a joint level. The comparison of joint moments and suit assistive forces allows us to monitor the degree of synchronicity between the user and the robot. Surface electromyography (sEMG) can be used to selectively monitor muscular activity focusing on the muscle groups that are most relevant for the task under consideration. Comparing the ensemble average profiles of sEMG activity between the unpowered, active and no suit conditions allows us to determine effects on the maximum force being delivered by each muscle (peak sEMG activation) and on the energy cost of each muscle activation (integral sEMG). We use the metabolic cost of walking as a global physiological measurement to determine to what extent the suit is assisting the wearer and if assistance offsets the weight of the device.
          • Translational applications

          • In addition to our work on basic research and system development, we are highly interested in pursuing applications of our soft wearable robots. Through our DARPA funded work, we are interested in developing exosuits that can assist soldiers walking while carrying heavy loads. Our belief is we can create passive and active systems that offload the high forces in the muscles and tendons in the leg – thus reducing the risk of injury and increasing the walking efficiency of the wearer. Another translational focus of our group is on gait assistance for medical applications. We foresee soft exosuits being able to restore mobility on patients with muscle weakness (e.g. elderly) or who suffer from a neurological disease such as a Stroke. Beyond our active systems, we envision translational potential in the area of sports and recreation where fully passive soft suits with structured functional textiles can provide small amounts of assistance during walking, hiking, running and other activities.
        • Soft Robotics

            • Multi-material fluidic actuators

            • Soft fluidic actuators consisting of elastomeric matrices with embedded flexible materials (e.g. cloth, paper, fiber, particles) are of particular interest to the robotics community because they are lightweight, affordable and easily customized to a given application. These actuators can be rapidly fabricated in a multi-step molding process and can achieve combinations of contraction, extension, bending and twisting with simple control inputs such as pressurized fluid. In our approach is to use new design concepts, fabrication approaches and soft materials to improve the performance of these actuators compared to existing designs. In particular, we use motivating applications (e.g. heart assist devices, soft robotic gloves) to define motion and force profile requirements. We can then embed mechanical intelligence into these soft actuators to achieve these performance requirements with simple control inputs.
            • Modeling of soft actuators

            • Characterizing and predicting the behavior of soft multi-material actuators is challenging due to the nonlinear nature of both the hyper-elastic material and the large bending motions they produce. We are working to comprehensively describe the principle of operation of these actuators through analytical, numerical and experimental approaches and characterize their outputs (motion and force) as a function of input pressure as well as geometrical and material parameters. Both models and experiments offer insight into the actuator behavior and the design parameters that affect it. We envision this work will lead to improved predictive models that will enable us to rapidly converge on new and innovative applications of these soft actuators.
            • Sensing and control

            • In order to control soft actuators, we need means of monitoring their kinematics, interaction forces with objects in the environment and internal pressure. We accomplish this through the use of fully soft sensors, developed with collaborators, and miniature or flexible sensors that can be incorporated into the actuator design during the manufacturing process. For power and control, we use off the shelf components such as electronic valves, pumps, regulators, sensors, and control boards etc. to rapidly modulate the pressure inside the chambers of the actuators using feedback control of pressure, motion and force. In addition, we can use the analytical models we develop to estimate state variables that may be difficult to measure directly.
            • Translational applications

            • There are approximately four million chronic stroke survivors with hemiparesis in the US today and another six million in developed countries globally. In addition, there are millions of other individuals suffering from similar conditions. For the majority of these cases, loss of hand motor ability is observed, and whether partial or total, this can greatly inhibit activities of daily living (ADL) and can considerably reduce one’s quality of life. To address these challenges, we are developing a modular, safe, portable, consumable, at-home hand rehabilitation and assistive device that aims to improve patient outcomes by significantly increasing the quantity (i.e. time) and quality of therapy at a reduced cost while also improving independence of users with chronic hand disabilities by enabling them to perform activities of daily living.

              In the United States, the lifetime risk of developing heart failure is roughly 20%. The current clinical standard treatment is implantation of a ventricular assist device that contacts the patient’s blood and is associated with thromboembolic events, hemolysis, immune reactions and infections. We are applying the field of soft robotics to develop a benchtop cardiac simulator and a Direct Cardiac Compression (DCC) device employing soft actuators in an elastomeric matrix. DCC is a non-blood contacting method of cardiac assistance for treating heart failure involving implantation of a device that surrounds the heart and contracts in phase with the native heartbeat to provide direct mechanical assistance during the ejection phase (systole) and the relaxation phase (diastole) of the cardiac cycle.
          • Université Libre de Bruxelles (ULB)

              • Portable Arm Exoskeleton

              • In many teleoperated or virtual activities with force feedback, the use of a fully portable haptic device would increase the easiness and performances of the command task, compared to devices linked to the ground or a table. Applications range from robotic arm teleoperation in severe environments (space, nuclear reactors, deep waters…). to applications in virtual reality either in the domain of virtual training in large volumes (such as virtual assembly) by means of immersion caves or head mounted displays or in the domain of stroke patients rehabilitation. As the operator does not have to be linked to a fixed base, or in environments with obstacles and as a multi-DOF portable device allows force feedback on several contact points, the operator is more immersed in the environment during the manipulation.

                The Sensoric Arm Master (SAM) has been designed as a wearable haptic interface with a serial kinematics, isomorphic to the human arm. SAM contains 7 actuated DOF corresponding to the joints of the human arm (shoulder, elbow and wrist flexion/extension, shoulder and wrist adduction/abduction, arm and forearm pronation/supination) and 6 sliders allowing morphological adaptation between active joints and human articulations. That corresponds to a good compromise between operator immersion capabilities (maximised workspace and no singularity) and mechanical complexity. Each joint of the exoskeleton has a similar conception with a local actuator, a position and torque sensor, allowing several kinds of control strategies (impedance, admittance control). The actuation has been selected with a compact system composed of a brushed DC motor, a capstan and gearbox.
                  • SAM exoskeleton

                  • Sam joint design

                • University of California, Santa Cruz

                    • Wearable Robotics - Exoskeletons

                    • The exoskeleton robot is worn by the human operator as an orthotic device. Its joints and links correspond to those of the human body. The same system operated in different modes can be used for three fundamental applications: a human-amplifier assistive device sharing a portion of the external load with the operator, haptic device, and automatic physiotherapy.

                      The current research effort with the upper limb exoskeleton is focused on the developing human machine interface (bioport) at the neuromuscular level using EMG (electromyography) signals as the primary command signal to the system. The research effort with the lower limb exoskeleton is focused on developing a semi active system for improving the ability of the operator to carry a payload.
                        • Exoskeleton Prototype 1 (EXO-UL1)

                        • The first exoskeleton mechanism consisted of a two-link, two-joint device corresponding to the upper and the lower arm and to the shoulder and elbow joints of the human body. The system included a weight plate (external load) that can be attached to the tip of the exoskeleton forearm link. The mechanism was fixed to the wall and positioned parallel to the sagittal plane of the operator. The human/exoskeleton mechanical interface included the upper arm bracelet, located at the upper arm link, and a handle grasped by the operator. This two-joint mechanism was used as a one-degree of freedom system by fixing the system shoulder joint at specific angles in the range of 0-180 Deg. The elbow joint was free to move in an angle range of 0-145 Deg, and included built-in mechanical constraints which kept the exoskeleton joint angle within the average human anthropometric boundaries. Since the human arm and the exoskeleton were mechanically linked the movements of the forearms of both the human and the exoskeleton were identical.
                          The basic purpose of the exoskeleton system as an assistance device is to amplify the moment generated by the human muscles relative to the elbow joint, while manipulating loads. The exoskeleton's elbow joint was powered by a DC servo motor (ESCAP-35NT2R82) with a stall torque of 360 mNm equipped with a planetary gearbox (ESCAP-R40) with a gear ratio of 1:193 and a maximal output torque of 40 Nm. An optical incremental shaft encoder (HP HEDS 5500) with 500 lines was attached to the motor shaft. Due to the encoder location and the high gear ratio, the practical encoder's resolution for measuring the joint angle was 0.0036 Deg. This setup incorporated a DC motor with the highest torque-to-weight ratio that was available on the commercial market at that time with a power consumption that could be provided by a battery. A high energy density of the power supply and an actuator with a high torque-to-weight ratio are two key features of the exoskeleton system as a self contained mobile medical assistance device for the disabled community. Limits imposed by present technology on these two key components along with design requirements for developing a compact system with a potential of serving as a medical assistance device for disabled person restricted the payload to be 5 Kg. However, this biomedical oriented design does not restrict the generality of the exoskeleton concept or its operational algorithms. Using other actuation systems, like hydraulic system increases the load capacity substantially.
                          The exoskeleton forearm was extended by a rod with a special connector for attaching disk-type weights (external load). Two force sensors (TEDEA 1040) were mounted at the interfaces between the exoskeleton and the tip carrying the external load and between the exoskeleton and the human hand. The first load cell, inserted between the rod holding the external load and the exoskeleton forearm link, measured the actual shear force, normal to the forearm axis, applied by the external load. The second load cell was installed between the handle grasped by the human hand and the forearm link of the exoskeleton. This load cell measured the shear force applied by the operator to the handle. Multiplying the sensors' measurements by the corresponding moment arms indicated the moments applied by the weights and by the human hand relative the elbow joint.

                          Surface EMG electrodes (8 mm Ag-AgCl BIOPAC - EL208S) were attached to the subject’s skin by adhesive disks for measuring the EMG signal of the Biceps Brachii and Triceps Brachii medial-head muscles. The signals were gained by EMG amplifiers (BIOPAC - EMG100A) using a gain factor in the range of 2000-5000 (depending on the subject). The EMG signals and the load cell signal were acquired by an A/D convector (Scientific Solution Lab Master 12 bit internal PC card) with a 1 kHz sampling rate, whereas the encoder signals were counted by custom-made hardware. The entire data set was recorded simultaneously and stored, for later off-line analysis and simulation.
                          A special real-time software, for operating the system, was written in C and run on a PC-based platform. The software was composed of three main modules. The first module dealt with the hardware/software interface. It controlled the interaction between the PC and the external motor driver and the sensors, through a D/A and an A/D card. The second module included the automatic code generated by the MATLAB - Simulink Real-Time toolbox. The third module was the user interface module which allowed to set various run time operational parameters. All the modules were compiled and linked for generating an efficient real-time software.

                        • Exoskeleton Prototype 2 (EXO-UL3)

                        • The second exoskeleton mechanism consisted of a three-link, two-joint device corresponding to the upper and the lower arm and to the shoulder and elbow joints of the human body. The system included a weight plate (external load) that can be attached to the tip of the exoskeleton forearm link. The mechanism was fixed to the wall and positioned parallel to the sagittal plane of the operator. The human/exoskeleton mechanical interface included the upper arm bracelet, located at the upper arm link, and a handle grasped by the operator. This two-joint mechanism was used as a two-degree of freedom system. The elbow and the shoulder joints were free to move in their anatomical range of motion. The mechanism included built-in mechanical constraints which kept the exoskeleton joint angles within the average human anthropometric boundaries. Since the human arm and the exoskeleton were mechanically linked the movements of the forearms and the upper arm of both the human and the exoskeleton were identical.
                          The basic purpose of the exoskeleton system as an assistance device is to amplify the moment generated by the human muscles relative to the elbow joint, while manipulating loads. The exoskeleton's elbow and shoulder joints were powered by a DC servo motor (ESCAP-35NT2R82) with a stall torque of 360 mNm equipped with a planetary gearbox (ESCAP-R40) with a gear ratio of 1:193 and a maximal output torque of 40 Nm. An optical incremental shaft encoder (HP HEDS 5500) with 500 lines was attached to the motor shaft. Due to the encoder location and the high gear ratio, the practical encoder's resolution for measuring the joint angle was 0.0036 Deg. This setup incorporated a DC motor with the highest torque-to-weight ratio that was available on the commercial market at that time with a power consumption that could be provided by a battery. A high energy density of the power supply and an actuator with a high torque-to-weight ratio are two key features of the exoskeleton system as a self contained mobile medical assistance device for the disabled community. Limits imposed by present technology on these two key components along with design requirements for developing a compact system with a potential of serving as a medical assistance device for disabled person restricted the payload to be 5 Kg. However, this biomedical oriented design does not restrict the generality of the exoskeleton concept or its operational algorithms. Using other actuation systems, like hydraulic system increases the load capacity substantially.
                          The exoskeleton forearm was extended by a rod with a special connector for attaching disk-type weights (external load). Four force sensors (TEDEA 1040) were mounted at the interfaces between the exoskeleton and the operator, one at the tip carrying the external load, two between the exoskeleton and the human hand and one at the interface between the upper arm and the exoskeleton. The first load cell, inserted between the rod holding the external load and the exoskeleton forearm link, measured the actual shear force, normal to the forearm axis, applied by the external load. The other load cells were installed between the handle grasped by the human hand and the forearm link of the exoskeleton and between the upper arm bracelet and the exoskeleton upper link. These load cells measured the shear forces applied by the operator to the mechanism. Multiplying the sensors' measurements by the corresponding moment arms indicated the moments applied by the weights and by the human arm relative the elbow and the shoulder joints.

                          Surface EMG electrodes (8 mm Ag-AgCl BIOPAC - EL208S) were attached to the subject’s skin by adhesive disks for measuring the EMG signal of the Biceps Brachii and Triceps Brachii medial-head muscles. The signals were gained by EMG amplifiers (BIOPAC - EMG100A) using a gain factor in the range of 2000-5000 (depending on the subject). The EMG signals and the load cell signal were acquired by an A/D convector (Scientific Solution Lab Master 12 bit internal PC card) with a 1 kHz sampling rate, whereas the encoder signals were counted by custom-made hardware. The entire data set was recorded simultaneously and stored, for later off-line analysis and simulation.
                          A special real-time software, for operating the system, was written in C and run on a PC-based platform. The software was composed of three main modules. The first module dealt with the hardware/software interface. It controlled the interaction between the PC and the external motor driver and the sensors, through a D/A and an A/D card. The second module included the automatic code generated by the MATLAB - Simulink Real-Time toolbox. The third module was the user interface module which allowed to set various run time operational parameters. All the modules were compiled and linked for generating an efficient real-time software.

                        • Exoskeleton Prototype 3 (EXO-UL3)

                        • Integrating human and robot into a single system offers remarkable opportunities for creating a new generation of assistive technology for both healthy and disabled people. Humans possess naturally developed algorithms for control of movement, but they are limited by their muscle strength. In addition, muscle weakness is the primary cause of disability for most people with neuromuscular diseases and injuries to the central nervous system. In contrast, robotic manipulators can perform tasks requiring large forces; however, their artificial control algorithms do not provide the flexibility to perform in a wide range of fuzzy conditions while preserving the same quality of performance as humans. It seems therefore that combining these two entities, the human and the robot, into one integrated system under the control of the human, may lead to a solution that will benefit from the advantages offered by each subsystem.
                          The exoskeleton robot, serving as an assistive device, is worn by the human (orthotic) and functions as a human-amplifier. Its joints and links correspond to those of the human body, and its actuators share a portion of the external load with the operator. One of the primary innovative ideas of the proposed research is to set the Human Machine Interface (HMI) at the neuromuscular level of the human physiological hierarchy using the body's own neural command signals as one of the primary command signals of the exoskeleton. These signals will be in the form of processed surface electromyography (sEMG) signals, detected by surface electrodes placed on the operator's skin. The proposed HMI takes advantage of the electro-chemical-mechanical delay, which inherently exists in the musculoskeletal system, between the time when the neural system activates the muscular system and the time when the muscles generate moments around the joints. The myoprocessor is a model of the human muscle running in real-time and in parallel to the physiological muscle. During the electro-chemical-mechanical time delay, the system will gather information regarding the physiological muscle’s neural activation level based on processed sEMG signals, the joint position, and angular velocity, and will predict using the myoprocessor the force that will be generated by the muscle before physiological contraction occurs. By the time the human muscles contract, the exoskeleton will move with the human in a synergistic fashion, allowing natural control of the exoskeleton as an extension of the operator's body.
                          The goal of this research is to design, build, and study the integration of a powered exoskeleton controlled by myosignals for the human arm. The research will pursue this goal through several objectives: (i) developing an 8 degrees of freedom powered anthropomorphic exoskeleton for the arm, including grasping/releasing; (ii) setting the HMI at the neuromuscular level by using processed sEMG signals as the primary command signal to the exoskeleton system; (iii) developing muscle models (myoprocessor) for predicting the human arm joints' torques; (iv) developing control algorithms that will fuse information from multiple sensors and will guarantee stable exoskeleton operation; (v) evaluating the overall performance of the integrated system using standardized arm/hand function tests. These goals and objectives will be pursued using several experimental protocols aimed at developing the myoprocessors and evaluating the exoskeleton performance. The proposed experimental protocol includes only healthy subjects as the first step in a long-term goal aimed to evaluate the exoskeleton performance with disabled subjects suffering from various neurological disabilities, such as stroke, spinal cord injury, muscular dystrophies, and other neurodegenerative disorders.

                          It is anticipated that the proposed research will advance the current knowledge in the field of modeling human muscles and their mathematical formulation. This knowledge will be further used to create a novel HMI and will permit a better understanding of the interaction between human and robot at the neural level. In addition, the proposed research will provide a tool and fundamental understanding regarding the development of an assistive technology for improving the quality of life of the disabled community. The proposed scientific activity will promote interdisciplinary collaboration between students and faculty members from the fields of electrical engineering, mechanical engineering, bioengineering, and rehabilitation medicine.