Keywords: Locomotion & Posture in Therapeutic Robotics, Automated Therapy in Therapeutic Robotics, Neuro-Rehabilitation in Therapeutic Robotics
Abstract: This paper describes the Sarcos Treadport locomotion interface, a large tilting treadmill whose unique aspect is the application of forces to a user's torso. The application of torso forces is necessary to provide missing inertial forces during acceleration on a treadmill and to stop a user from walking through virtual walls. Torso forces can also substitute for treadmill tilt, as has been validated by psychological, biomechanical and energetic studies. A harness has been designed to transmit forces to the torso with minimum backlash while maintaining comfort. The experience of locomotion is integrated into a virtual environment comprised of a CAVElike visual display and head-tracked stereo sound synthesis. To complete the multi-sensory experience, atmospheric and olfactory displays are under development.

Keywords: Measures in Evaluation in Clinical Experience, Devices in Evaluation in Clinical Experience, Functional Outcomes in Clinical Experience
Abstract: Many people with disabilities rely upon items of assistive technology for their independence. However, in many cases, the potential of a specific assistive device is limited by the difficulties in actual user operation. Whilst success in use of a particular interface depends on appropriateness of the user’s skills to the interface physical characteristics, there is a need to develop novel systems that will provide quantitative skills relevant to interface operation. The i-match project, funded by the European Commission, focuses on quantifying upper limb skills and performance as well as characterising different interfaces based on their physical and functional characteristics. The objective is to aid the selection of an optimum interface by matching between user’s abilities to control and features of an existing interface. This paper overviews the project and different steps taken to produce a novel matching system.

Keywords: Novel Controls in Prosthetics/Orthotics, Lower-limb in Robotic Prosthetics/Orthotics, Automated Therapy in Therapeutic Robotics
Abstract: The rehabilitation robot LOKOMAT has been developed at the Spinal Cord Injury Center of the University Hospital Balgrist, Zurich. It allows automated treadmill training for patients with mobility impairment of the lower limbs. Former position control strategies did not allow voluntary active movements of the patient. This paper presents a new cooperative control architecture for the LOKOMAT that enforces active force contribution of the patient. Based on a dynamic model of the human gait the patient is supported by an arbitrary percentage of the force required to walk. Online gait event detectors have been developed and implemented since the controller mode changes depending on the gait phase. The new control strategy is highly patient-driven and enables the patient to accomplish free walking movements. Thus, it is expected, that the motivation of the patient will be maximized and the rehabilitation progress accelerated.

Keywords: Sensors in Hardware/Control Developments, Smart Home in Assistive Robotics, Kinematics in Sensory-Motor Control & Learning
Abstract: FRIEND II which is the successor of the rehabilitation robot FRIEND I is being developed at the Institute of Automation, University of Bremen, and belongs to the category ‘intelligent’ wheelchair mounted manipulators. Both systems are used as a personal assistant to support disabled persons with upper-limb impairments in daily life situations as well as in the working environment. Significant improvements are obtained with the use of smart devices, new camera systems, a humanlike robot arm with 7-joint kinematics, a new control concept – Kinematic Configuration Control, force torque sensor and two interchangeable grippers. This paper describes the hardware selection and the innovations in the hardware of the system FRIEND II currently under development.

Keywords: Control in Hardware/Control Developments, Smart Home in Assistive Robotics, Manipulation in Assistive Robotics
Abstract: Rehabilitation robots (e.g. FRIEND as intelligent wheelchair mounted manipulator) are being developed to gain their user’s autonomy within daily life environment. To prevent a high cognitive load onto the user, task input on a high level of abstraction is mandatory. State-of-the-art rehabilitation robots are still not capable to integrate fragments of intelligent behavior into an overall context and to solve complex tasks. A basic problem is how to cope with system complexity as well as computational complexity that evolve during task planning. A compromise towards feasibility is to equip the system’s environment with smart components that provide own intelligence and thus reduce the complexity of the robotic system. However, a structured approach is necessary to fuse the distributed intelligence. This paper is about the concept and realization of a software-framework being able to execute autonomous system operations together with information retrieving capabilities and user interactions within a distributed system. Key aspects of development have been to provide robust run-time behavior of the system along with the inclusion and resolving of redundant sensor information as well as to reduce the effort of system programming to a minimum. The application of the developed framework will be demonstrated on base of sample steps of its integration with the FRIEND II rehabilitation robotic system within an intelligent home environment.

Keywords: Mechanical systems in Hardware/Control
Abstract: In literature a high power to weight ratio is mentioned among the assumed advantages of pneumatic artificial muscles over other types of actuators. In this paper a comparison was made between pneumatic artificial muscle type actuators and cylinder actuators on the basis of energy to mass ratio. When compared to standard industrial cylinder actuators, it is shown that pneumatic artificial muscles have a somewhat better [+/- 30%] energy to mass ratio for short stroke applications [s < 20 mm] and are up to a factor of 2 better at longer strokes [s ≥ 200 mm]. However, a redesign of piston in cylinder actuators shows the energy to mass ratio of these cylinder actuators to be superior to pneumatic artificial muscles and to standard industrial cylinder actuators. The energy to mass ratio is a factor of 30 better at a stroke of s = 10 mm, declining to a factor of 4.8 for a stroke s = 900 mm. The standard industrial cylinders are over-dimensioned, thus initiating the euphoria about pneumatic artificial muscles. However, for many applications a more careful design of piston in cylinder actuators provides a far better energy to mass ratio. Therefore, the use of pneumatic artificial muscles is questionable, especially in applications where the energy to mass ratio is important, like (autonomous) robotics, rehabilitation, etc.

Keywords: Control in Hardware/Control Developments, Locomotion & Posture in Therapeutic Robotics, Neuro-Rehabilitation in Therapeutic Robotics
Abstract: The paper presents the simulation and modeling of gait on a system using two prototype compact Stewart platforms. Control issues raised by the reduced size of the robots and hence their lower power output are discussed. The flexible haptic material concept is introduced and used to realistically model heterogeneous haptic surfaces simulating the virtual ground. An algorithm for virtual foot/virtual surface contact modeling and transforming the platform motion into walking in VEs is also presented.

Keywords: Novel Techniques in Therapeutic Robotics, Control in Hardware/Control Developments, Manipulation in Assistive Robotics
Abstract: The purpose of this study was to investigate the locomotor activity of spinal cord contused rats in response to robot-assisted extension of their hindlimbs. Nineteen rats received a contusion injury to the mid-thoracic spinal cord. We used a robotic gait-training device (“the rat stepper”) and a robotic paw platform (the “slide”) to pull the animals’ hindlimbs into extension. The injured rats initiated swing with a significantly greater probability (p < 0.001) when the rat stepper pulled their hindlimbs into extension on a conventional treadmill (75+/-16.9%) as compared to the treadmill pulling their hindlimbs into extension with no robotic assistance (38.9+/-16.6%). Furthermore, using the rat stepper to extend one hindlimb and hold the other in stance while on the slide resulted in more unilateral stepping, rather than bilateral hopping activity, when compared to the extension of both hindlimbs simultaneously (81±0.24% vs. 43±0.34%, p < 0.001). Continuous training of one animal from each injury group with robot-assisted extension and appropriate interlimb phasing using the rat stepper and slide yielded substantially more steps in a two-minute training period when compared to training with a conventional treadmill (84 steps on average vs 12 steps on average). These results indicate that a greater amount of alternating stepping activity can be elicited by appropriately-phased, robot-assisted extension of an animal’s hindlimb, thereby providing possible benefits to evaluation and training of gait following SCI.

Keywords: Training Programs in Therapeutic Robotics, Novel Techniques in Therapeutic Robotics, Neuro-Rehabilitation in Therapeutic Robotics
Abstract: We studied the effects of Robotic-Assisted Locomotor (LOKOMAT) Training on the neuromuscular mechanical properties and voluntary movement of the spastic ankle in persons with incomplete Spinal Cord Injury (SCI). System identification techniques were used to characterize the effects of Lokomat training on the mechanical abnormalities of the ankle joint. We also determined the effects of this physical training on repeated voluntary movements of the ankle from full plantarflexion to dorsiflexion at maximum speed, quantified by measuring their kinematics parameters. We found that reflex stiffness, abnormally increased in SCI, was significantly reduced following LOKOMAT training. Active range of motion, peak-velocity and peak-acceleration of voluntary movement increased as a result of LOKOMAT training. These findings demonstrate that LOKOMAT training has a potential to modified abnormal reflex function and improve impaired voluntary movement.

Keywords: Locomotion & Posture in Therapeutic Robotics, Automated Therapy in Therapeutic Robotics
Abstract: We are developing a robotic device, PAM (Pelvic Assist Manipulator), that assists the pelvic motion during human gait training on a treadmill. PAM allows naturalistic motion of pelvis actuated by six pneumatic cylinders, which, combined with a nonlinear force-tracking controller, provide backdrivability and large force output at a relatively low cost. PAM can act as a teach-and-replay device with a PD position controller driving the pelvis onto the reference trajectory specified with or without the help of therapists. During initial experiments with unimpaired subjects, we encountered a problem in which the subjects had difficulty synchronizing their movements with the gait pattern reproduced by PAM, even though that gait pattern had been sampled from the subjects themselves. We introduced footswitches to detect the gait timing and developed a feedback control algorithm that adjusts the play-back speed of the gait pattern in real-time. The feedback algorithm is presented, along with data that shows the effectiveness of the algorithm in synchronizing the robotic assistance during stepping by unimpaired subjects, even when the subjects change their step size and period.

Keywords: Manipulation in Assistive Robotics, Novel Techniques in Therapeutic Robotics, Interfaces in Hardware/Control Developments
Abstract: In physical and occupational therapy two people interact through force and motion. Other common examples of this interaction include lifting and moving a bulky object, teaching manual skills, dancing, and handing off a baton or a drinking glass. These tasks involve kinesthetic interaction, a communication channel distinct from spoken language and gestures. Understanding kinesthetic interaction should be important in designing robots to assist with physical and occupational therapy.

In this paper we describe our experiments on kinesthetic interaction between two people cooperating on a 1 degree of freedom task. We characterize the interaction forces between the two people, dividing them into a productive “net force” and an orthogonal “difference force.” Our results suggest three effects (1) an emergent specialization of the two participants into different roles, (2) an oscillation of forces at about 8 Hz, and (3) a steady force in opposition to one another that could be analogous to co-contraction in an individual.

Keywords: Manipulation in Assistive Robotics, Plasticity in Sensory-Motor Control & Learning, Training Programs in Therapeutic Robotics
Abstract: This paper studies the possible benefit that can be obtained by introducing variability into the robotic control of trajectories used to train hindlimb locomotion in adult spinal mice. The spinal cords of adult female Swiss-Webster mice were completely transected at a mid-thoracic level. Fourteen days post-transection, the spinal mice were robotically trained to step in the presence of a 5-HT agonist, quipazine, for a period of six weeks. In this pilot study nine animals were divided into three groups, each receiving a different control strategy: a fixed training trajectory (Group A), a variable training trajectory without interlimb coordination imposed (Group B) and a variable training trajectory with hindlimb bilateral coordination imposed (Group C). Preliminary results indicate that Group A recovers more slowly than the two groups receiving variable modes of robotic training. Groups B and C show higher levels of recovery than Group A in terms of the number of steps performed during testing sessions, as well as in their step periodicity and shape consistency. Group C displays a higher incidence of alternating stepping than Group B. These results indicate that variable trajectory robotic training paradigms may be more effective than fixed trajectory paradigms in promoting robust post-injury stepping behavior. Furthermore, it appears that the inclusion of interlimb coordination is an important contribution to successful training.