Background: When humans are faced with an unstable task, two different stabilization mechanisms a... more Background: When humans are faced with an unstable task, two different stabilization mechanisms are possible: a highstiffness strategy, based on the inherent elastic properties of muscles/tools/manipulated objects, or a low-stiffness strategy, based on an explicit positional feedback mechanism. Specific constraints related to the dynamics of the task and/or the neuromuscular system often force people to adopt one of these two strategies. Methodology/Findings: This experiment was designed such that subjects could achieve stability using either strategy, with a marked difference in terms of effort and control requirements between the two strategies. The task was to balance a virtual mass in an unstable environment via two elastic linkages that connected the mass to each hand. The dynamics of the mass under the influence of the unstable force field and the forces applied through the linkages were simulated using a bimanual, planar robot. The two linkages were non-linear, with a stiffness that increased with the amount of stretch. The mass could be stabilized by stretching the linkages to achieve a stiffness that was greater than the instability coefficient of the unstable field (high-stiffness), or by balancing the mass with sequences of small force impulses (low-stiffness). The results showed that 62% of the subjects quickly adopted the high-stiffness strategy, with stiffness ellipses that were aligned along the direction of instability. The remaining subjects applied the low-stiffness strategy, with no clear preference for the orientation of the stiffness ellipse. Conclusions: The choice of a strategy was based on the bimanual coordination of the hands: high-stiffness subjects achieved stability quickly by separating the hands to stretch the linkages, while the low-stiffness subjects kept the hands close together and took longer to achieve stability but with lower effort. We suggest that the existence of multiple solutions leads to different types of skilled behavior in unstable environments.
Studies in health technology and informatics, 2009
Robot therapy seems promising with stroke survivors, but it is unclear which exercises are most e... more Robot therapy seems promising with stroke survivors, but it is unclear which exercises are most effective, and whether other pathologies may benefit from this technique. In general, exercises should exploit the adaptive nature of the nervous system, even in chronic patients. Ideally, exercise should involve multiple sensory modalities and, to promote active subject participation, the level of assistance should be kept to a minimum. Moreover, exercises should be tailored to the different degrees of impairment, and should adapt to changing performance. To this end, we designed three tasks: (i) a hitting task, aimed at improving the ability to perform extension movements; (ii) a tracking task, aimed at improving visuo-motor control; and (iii) a bimanual task, aimed at fostering inter-limb coordination. All exercises are conducted on a planar manipulandum with two degrees of freedom, and involve alternating blocks of exercises performed with and without vision. The degree of assistance is kept to a minimum, and adjusted to the changing subject's performance. All three exercises were tested on chronic stroke survivors with different levels of impairment. During the course of each exercise, movements became faster, smoother, more precise, and required decreasing levels of assistive force. These results point to the potential benefit of that assist-as-needed training with a proprioceptive component in a variety of clinical conditions.
IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2017
It is known that physical coupling between two subjects may be advantageous in joint tasks. Howev... more It is known that physical coupling between two subjects may be advantageous in joint tasks. However, little is known about how two people mutually exchange information to exploit the coupling. Therefore, we adopted a reversed, novel perspective to the standard one that focuses on the ability of physically coupled subjects to adapt to cooperative contexts that require negotiating a common plan: we investigated how training in pairs on a novel task affects the development of motor skills of each of the interacting partners. The task involved reaching movements in an unstable dynamic environment using a bilateral non-linear elastic tool that could be used bimanually or dyadically. The main result is that training with an expert leads to the greatest performance in the joint task. However, the performance in the individual test is strongly affected by the initial skill level of the partner. Moreover, practicing with a peer rather than an expert appears to be more advantageous for a naive; and motor skills can be transferred to a bimanual context, after training with an expert, only if the non-expert subject had prior experience of the dynamics of the novel task. Index Terms-Physical human-robot interaction, motor learning, skill learning, neural control of movement, humanhuman interaction.
2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015
Previous works have shown that, when dealing with instabilities in a bimanual manipulation paradi... more Previous works have shown that, when dealing with instabilities in a bimanual manipulation paradigm, humans modulate the stiffness of the arms according to feedforward or feedback mechanisms as a function of the dynamics of the task. The aim of this work is to complement these results getting insights on how the CNS controls the muscles to achieve the stabilization goal in the two aforementioned control strategies. Surface EMG was recorded from 13 muscles of each arm and trunk while three expert subjects performed bimanual balancing of a virtual underactuated tool immersed in an unstable force-field. Results suggest the existence of an intermittent muscle ensemble recruitment that follows two distinct activation patterns, namely synchronous co-contractions and independent activations. The observed EMG patterns were independent of the motor control strategy applied in the task. These findings therefore suggest the existence of separate control strategies for the tool stabilization and the control of hand movements at the muscular level during a bimanual postural task.
2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015
In the context of unstable tasks, whenever the dynamics of the interaction are unknown, our abili... more In the context of unstable tasks, whenever the dynamics of the interaction are unknown, our ability to control an object depends on the predictability of the sensory feedback generated from the physical coupling at the interface with the object. In the case of physical human-human interaction, the haptic sensory feedback plays a primary role in the construction of a shared motor plan, being the channel for the mutual sharing of intentions. The present work addresses the issue of strategy selection in contexts in which instability is arising both from the environment, i.e. controlling a compliant object subject to nonlinear forces, and from the interaction with a partner, i.e. carrying out a bimanual balancing task in the presence of disturbing force-fields.
2015 IEEE International Conference on Rehabilitation Robotics (ICORR), 2015
Several studies support the hypothesis that robot assisted therapy for adult subjects with motor ... more Several studies support the hypothesis that robot assisted therapy for adult subjects with motor impairments resulting from neurological damages can be beneficial in promoting the recovery process when conveyed in conjunction to conventional rehabilitation. Robotic therapy has been mainly applied to adult subjects and little is known about children or youth. This study presents the results of a robot-assisted rehabilitation training protocol applied to two young subjects suffering of hemiparesis. Robotic therapy was applied to the distal portion of the affected upper limb, through a fully backdrivable exoskeleton that allows full range of motion over the three degrees of freedom of the wrist. The training protocol consisted of ten therapy sessions and two days of robotic and clinical assessment pre and post training. With the main purpose of reducing the degree of motor impairment and promoting recovery, a control scheme was implemented which is characterized by an adaptive assistance delivered to the subjects as to help them completing the therapeutic task. The implementation of the new haptic controller is discussed in details and results are reported comparing the effect of robotic therapy for both dynamic and kinematic changes at the beginning and at end of the experiment. The results show that robot-assisted training successfully improved hand and wrist movement ability and promoted upper extremity functional recovery, thus highlighting the effectiveness of robotic therapy for both dynamic and kinematic motor performance.
2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2014
An intact position sense is considered important for neuromotor recovery, but the available metho... more An intact position sense is considered important for neuromotor recovery, but the available methods and protocols for its assessment are still limited. In the clinical practice it is generally tested trough a bimanual position matching test, that consists of replicating with one arm the angular positions of the other arm in space (intrinsic coordinates matching). However, the same test could be carried out by matching the hand location in space (extrinsic coordinates matching). Is there any difference between the procedures that may be relevant to the evaluation of position sense deficits? In this study we compared the performance of eight right handed subjects and two stroke survivors with left hemiparesis performing the test in the two conditions. A robotic manipulandum passively moved the left arm of the participants in twenty-four positions in the workspace. Subjects had to match the left arm position with their right arm either in intrinsic or extrinsic coordinates. The results show that all the subjects (impaired and controls) performed better when using the extrinsic paradigm.
2009 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2009
We report on a pilot study of robot therapy with stroke patients. Patients were requested to trac... more We report on a pilot study of robot therapy with stroke patients. Patients were requested to track a continuously moving target according to a figure-of-eight. Assistance was provided by an attractive force field, whose magnitude was regulated according to a principle of minimal assistance and a principle of consolidation of the learned memory trace. From the analysis of the assistive forces, we show that subjects improve their degree of voluntary control.
The term Robotic Rehabilitation defines a class of machines employed for different scenarios, ran... more The term Robotic Rehabilitation defines a class of machines employed for different scenarios, ranging from therapeutic and assistive applications to robots devoted to neuroscience, behavioral research, and cognitive aspects. The first use of such technology dates back to early 1990s, with a relatively long history and it remains linked to the idea that robots, even with a certain degree of autonomy, must be directly controlled by humans while the interaction must be opportunely regulated in order to promote motor recovery or independent living. These devices are designed for individuals with neuromotor and cognitive disabilities to provide rehabilitative exercises or assistance for activity of daily living. They are also measurement systems i.e. they can incorporate sensors for monitoring kinematic and kinetic interaction with subjects such as movement, force or inertial sensors, or for detecting EMG signals to trigger the assistance or to provide – in more complex architectures – Functional Electric Stimulation (FES) to promote motor activity. In this chapter we will focus on therapeutic robots, which are usually employed to perform rehabilitation protocol, describing in details the most widely used control architectures, the implementation of rehabilitation exercises to restore specific motor functions and the measures of the corresponding performance.
2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2014
Human-human physical interaction has proven to be advantageous especially in contexts with high c... more Human-human physical interaction has proven to be advantageous especially in contexts with high coordination requirements. But under which conditions can haptic communication bring to performance benefits in a challenging cooperative environment? In this work we investigate which are the dynamics that intervene when two subjects are required to switch from a bimanual to a dyadic configuration in order to solve a complex reaching and stabilization task of a virtual tool in the presence of an unstable dynamics. Results show that dyadic cooperation can improve the performance respect to the individual condition, while minimizing the effort. However, in the joint task, when the stiffness of the system becomes harder to manipulate the feedback delays appear to be critical in determining the maximum achievable level of performance.
19th International Symposium in Robot and Human Interactive Communication, 2010
The goal of this study is to better understand how the central nervous system chooses a stable co... more The goal of this study is to better understand how the central nervous system chooses a stable control strategy when presented with an unstable task. A haptic, bimanual manipulandum has been used to implement an unstable task, which requires subjects to stabilize a mass-load under the action of a saddle force field with two non-linear springs, whose stiffness increases when
2009 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2009
In relation with a recent Cochrane review, the paper discusses desirable features of a &a... more In relation with a recent Cochrane review, the paper discusses desirable features of a "humanoid" robot-therapist: 1) high mechanical compliance, 2) large range of force, 3) minimum assistance level, 4) soft haptic interaction for proprioceptive awareness, 5) adaptative assistance properties. It also proposes a framework for addressing optimal assistance and learning paradigms in view of a consensus in the community of rehabilitation engineers about shared principles and common standards.
Although proprioceptive impairment is likely to affect in a significant manner the capacity of st... more Although proprioceptive impairment is likely to affect in a significant manner the capacity of stroke patients to recover functionality of the upper limb, clinical assessment methods in current use are rather crude, with a low level of reliability and a limited capacity to discriminate the relevant features of the deficits. In this paper we describe a new technique based on robot technology, with the goal of providing a reliable, accurate, quantitative evaluation of the position sense in peri-personal space. The proposed technique uses a bimanual, planar robot manipuladum (BdF device), whose handles are grasped by the blindfolded patient: the paretic hand is passively placed in one of 17 positions and the subject is asked to actively match the paretic hand position in space with the other hand. The position sense of the paretic arm and the corresponding deficit of space representation are characterized by means of 7 indicators: 1) positional error; 2) holding force; 3) medio/lateral shift; 4) antero/posterior shift; 5) medio/lateral skew; 6) antero/posterior skew; 7) shrink coefficient. We also show how the same experimental setup can be used for "proprioceptive training", i.e. for providing robot assistance to the paretic arm that may improve the position sense of the patient. A preliminary, feasibility test has been carried out with one patient and three controls.
Journal of neuroengineering and rehabilitation, Jan 9, 2017
Several neurodevelopmental disorders and brain injuries in children have been associated with pro... more Several neurodevelopmental disorders and brain injuries in children have been associated with proprioceptive dysfunction that will negatively affect their movement. Unfortunately, there is lack of reliable and objective clinical examination protocols and our current knowledge of how proprioception evolves in typically developing children is still sparse. Using a robotic exoskeleton, we investigated proprioceptive acuity of the wrist in a group of 49 typically developing healthy children (8-15 years), and a group of 40 young adults. Without vision participants performed an ipsilateral wrist joint position matching task that required them to reproduce (match) a previously experienced target position. All three joint degrees-of-freedom of the wrist/hand complex were assessed. Accuracy and precision were evaluated as a measure of proprioceptive acuity. The cross-sectional data indicating the time course of development of acuity were then fitted by four models in order to determine which...
This work examines physiological mechanisms underlying the position sense of the wrist, namely, t... more This work examines physiological mechanisms underlying the position sense of the wrist, namely, the codification of proprioceptive information related to pointing movements of the wrist toward kinesthetic targets. Twenty-four healthy subjects participated to a robotaided assessment of their wrist proprioceptive acuity to investigate if the sensorimotor transformation involved in matching targets located by proprioceptive receptors relies on amplitude or positional cues. A joint position matching test was performed in order to explore such dichotomy. In this test, the wrist of a blindfolded participant is passively moved by a robotic device to a preset target position and, after a removal movement from this position, the participant has to actively replicate and match it as accurately as possible. The test involved two separate conditions: in the first, the matching movements started from the same initial location; in the second one, the initial location was randomly assigned. Target matching accuracy, precision, and bias in the two conditions were then compared. Overall results showed a consistent higher performance in the former condition than in the latter, thus supporting the hypothesis that the joint position sense is based on vectorial or amplitude coding rather than positional.
Background: When humans are faced with an unstable task, two different stabilization mechanisms a... more Background: When humans are faced with an unstable task, two different stabilization mechanisms are possible: a highstiffness strategy, based on the inherent elastic properties of muscles/tools/manipulated objects, or a low-stiffness strategy, based on an explicit positional feedback mechanism. Specific constraints related to the dynamics of the task and/or the neuromuscular system often force people to adopt one of these two strategies. Methodology/Findings: This experiment was designed such that subjects could achieve stability using either strategy, with a marked difference in terms of effort and control requirements between the two strategies. The task was to balance a virtual mass in an unstable environment via two elastic linkages that connected the mass to each hand. The dynamics of the mass under the influence of the unstable force field and the forces applied through the linkages were simulated using a bimanual, planar robot. The two linkages were non-linear, with a stiffness that increased with the amount of stretch. The mass could be stabilized by stretching the linkages to achieve a stiffness that was greater than the instability coefficient of the unstable field (high-stiffness), or by balancing the mass with sequences of small force impulses (low-stiffness). The results showed that 62% of the subjects quickly adopted the high-stiffness strategy, with stiffness ellipses that were aligned along the direction of instability. The remaining subjects applied the low-stiffness strategy, with no clear preference for the orientation of the stiffness ellipse. Conclusions: The choice of a strategy was based on the bimanual coordination of the hands: high-stiffness subjects achieved stability quickly by separating the hands to stretch the linkages, while the low-stiffness subjects kept the hands close together and took longer to achieve stability but with lower effort. We suggest that the existence of multiple solutions leads to different types of skilled behavior in unstable environments.
Studies in health technology and informatics, 2009
Robot therapy seems promising with stroke survivors, but it is unclear which exercises are most e... more Robot therapy seems promising with stroke survivors, but it is unclear which exercises are most effective, and whether other pathologies may benefit from this technique. In general, exercises should exploit the adaptive nature of the nervous system, even in chronic patients. Ideally, exercise should involve multiple sensory modalities and, to promote active subject participation, the level of assistance should be kept to a minimum. Moreover, exercises should be tailored to the different degrees of impairment, and should adapt to changing performance. To this end, we designed three tasks: (i) a hitting task, aimed at improving the ability to perform extension movements; (ii) a tracking task, aimed at improving visuo-motor control; and (iii) a bimanual task, aimed at fostering inter-limb coordination. All exercises are conducted on a planar manipulandum with two degrees of freedom, and involve alternating blocks of exercises performed with and without vision. The degree of assistance is kept to a minimum, and adjusted to the changing subject's performance. All three exercises were tested on chronic stroke survivors with different levels of impairment. During the course of each exercise, movements became faster, smoother, more precise, and required decreasing levels of assistive force. These results point to the potential benefit of that assist-as-needed training with a proprioceptive component in a variety of clinical conditions.
IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2017
It is known that physical coupling between two subjects may be advantageous in joint tasks. Howev... more It is known that physical coupling between two subjects may be advantageous in joint tasks. However, little is known about how two people mutually exchange information to exploit the coupling. Therefore, we adopted a reversed, novel perspective to the standard one that focuses on the ability of physically coupled subjects to adapt to cooperative contexts that require negotiating a common plan: we investigated how training in pairs on a novel task affects the development of motor skills of each of the interacting partners. The task involved reaching movements in an unstable dynamic environment using a bilateral non-linear elastic tool that could be used bimanually or dyadically. The main result is that training with an expert leads to the greatest performance in the joint task. However, the performance in the individual test is strongly affected by the initial skill level of the partner. Moreover, practicing with a peer rather than an expert appears to be more advantageous for a naive; and motor skills can be transferred to a bimanual context, after training with an expert, only if the non-expert subject had prior experience of the dynamics of the novel task. Index Terms-Physical human-robot interaction, motor learning, skill learning, neural control of movement, humanhuman interaction.
2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015
Previous works have shown that, when dealing with instabilities in a bimanual manipulation paradi... more Previous works have shown that, when dealing with instabilities in a bimanual manipulation paradigm, humans modulate the stiffness of the arms according to feedforward or feedback mechanisms as a function of the dynamics of the task. The aim of this work is to complement these results getting insights on how the CNS controls the muscles to achieve the stabilization goal in the two aforementioned control strategies. Surface EMG was recorded from 13 muscles of each arm and trunk while three expert subjects performed bimanual balancing of a virtual underactuated tool immersed in an unstable force-field. Results suggest the existence of an intermittent muscle ensemble recruitment that follows two distinct activation patterns, namely synchronous co-contractions and independent activations. The observed EMG patterns were independent of the motor control strategy applied in the task. These findings therefore suggest the existence of separate control strategies for the tool stabilization and the control of hand movements at the muscular level during a bimanual postural task.
2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015
In the context of unstable tasks, whenever the dynamics of the interaction are unknown, our abili... more In the context of unstable tasks, whenever the dynamics of the interaction are unknown, our ability to control an object depends on the predictability of the sensory feedback generated from the physical coupling at the interface with the object. In the case of physical human-human interaction, the haptic sensory feedback plays a primary role in the construction of a shared motor plan, being the channel for the mutual sharing of intentions. The present work addresses the issue of strategy selection in contexts in which instability is arising both from the environment, i.e. controlling a compliant object subject to nonlinear forces, and from the interaction with a partner, i.e. carrying out a bimanual balancing task in the presence of disturbing force-fields.
2015 IEEE International Conference on Rehabilitation Robotics (ICORR), 2015
Several studies support the hypothesis that robot assisted therapy for adult subjects with motor ... more Several studies support the hypothesis that robot assisted therapy for adult subjects with motor impairments resulting from neurological damages can be beneficial in promoting the recovery process when conveyed in conjunction to conventional rehabilitation. Robotic therapy has been mainly applied to adult subjects and little is known about children or youth. This study presents the results of a robot-assisted rehabilitation training protocol applied to two young subjects suffering of hemiparesis. Robotic therapy was applied to the distal portion of the affected upper limb, through a fully backdrivable exoskeleton that allows full range of motion over the three degrees of freedom of the wrist. The training protocol consisted of ten therapy sessions and two days of robotic and clinical assessment pre and post training. With the main purpose of reducing the degree of motor impairment and promoting recovery, a control scheme was implemented which is characterized by an adaptive assistance delivered to the subjects as to help them completing the therapeutic task. The implementation of the new haptic controller is discussed in details and results are reported comparing the effect of robotic therapy for both dynamic and kinematic changes at the beginning and at end of the experiment. The results show that robot-assisted training successfully improved hand and wrist movement ability and promoted upper extremity functional recovery, thus highlighting the effectiveness of robotic therapy for both dynamic and kinematic motor performance.
2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2014
An intact position sense is considered important for neuromotor recovery, but the available metho... more An intact position sense is considered important for neuromotor recovery, but the available methods and protocols for its assessment are still limited. In the clinical practice it is generally tested trough a bimanual position matching test, that consists of replicating with one arm the angular positions of the other arm in space (intrinsic coordinates matching). However, the same test could be carried out by matching the hand location in space (extrinsic coordinates matching). Is there any difference between the procedures that may be relevant to the evaluation of position sense deficits? In this study we compared the performance of eight right handed subjects and two stroke survivors with left hemiparesis performing the test in the two conditions. A robotic manipulandum passively moved the left arm of the participants in twenty-four positions in the workspace. Subjects had to match the left arm position with their right arm either in intrinsic or extrinsic coordinates. The results show that all the subjects (impaired and controls) performed better when using the extrinsic paradigm.
2009 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2009
We report on a pilot study of robot therapy with stroke patients. Patients were requested to trac... more We report on a pilot study of robot therapy with stroke patients. Patients were requested to track a continuously moving target according to a figure-of-eight. Assistance was provided by an attractive force field, whose magnitude was regulated according to a principle of minimal assistance and a principle of consolidation of the learned memory trace. From the analysis of the assistive forces, we show that subjects improve their degree of voluntary control.
The term Robotic Rehabilitation defines a class of machines employed for different scenarios, ran... more The term Robotic Rehabilitation defines a class of machines employed for different scenarios, ranging from therapeutic and assistive applications to robots devoted to neuroscience, behavioral research, and cognitive aspects. The first use of such technology dates back to early 1990s, with a relatively long history and it remains linked to the idea that robots, even with a certain degree of autonomy, must be directly controlled by humans while the interaction must be opportunely regulated in order to promote motor recovery or independent living. These devices are designed for individuals with neuromotor and cognitive disabilities to provide rehabilitative exercises or assistance for activity of daily living. They are also measurement systems i.e. they can incorporate sensors for monitoring kinematic and kinetic interaction with subjects such as movement, force or inertial sensors, or for detecting EMG signals to trigger the assistance or to provide – in more complex architectures – Functional Electric Stimulation (FES) to promote motor activity. In this chapter we will focus on therapeutic robots, which are usually employed to perform rehabilitation protocol, describing in details the most widely used control architectures, the implementation of rehabilitation exercises to restore specific motor functions and the measures of the corresponding performance.
2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2014
Human-human physical interaction has proven to be advantageous especially in contexts with high c... more Human-human physical interaction has proven to be advantageous especially in contexts with high coordination requirements. But under which conditions can haptic communication bring to performance benefits in a challenging cooperative environment? In this work we investigate which are the dynamics that intervene when two subjects are required to switch from a bimanual to a dyadic configuration in order to solve a complex reaching and stabilization task of a virtual tool in the presence of an unstable dynamics. Results show that dyadic cooperation can improve the performance respect to the individual condition, while minimizing the effort. However, in the joint task, when the stiffness of the system becomes harder to manipulate the feedback delays appear to be critical in determining the maximum achievable level of performance.
19th International Symposium in Robot and Human Interactive Communication, 2010
The goal of this study is to better understand how the central nervous system chooses a stable co... more The goal of this study is to better understand how the central nervous system chooses a stable control strategy when presented with an unstable task. A haptic, bimanual manipulandum has been used to implement an unstable task, which requires subjects to stabilize a mass-load under the action of a saddle force field with two non-linear springs, whose stiffness increases when
2009 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2009
In relation with a recent Cochrane review, the paper discusses desirable features of a &a... more In relation with a recent Cochrane review, the paper discusses desirable features of a "humanoid" robot-therapist: 1) high mechanical compliance, 2) large range of force, 3) minimum assistance level, 4) soft haptic interaction for proprioceptive awareness, 5) adaptative assistance properties. It also proposes a framework for addressing optimal assistance and learning paradigms in view of a consensus in the community of rehabilitation engineers about shared principles and common standards.
Although proprioceptive impairment is likely to affect in a significant manner the capacity of st... more Although proprioceptive impairment is likely to affect in a significant manner the capacity of stroke patients to recover functionality of the upper limb, clinical assessment methods in current use are rather crude, with a low level of reliability and a limited capacity to discriminate the relevant features of the deficits. In this paper we describe a new technique based on robot technology, with the goal of providing a reliable, accurate, quantitative evaluation of the position sense in peri-personal space. The proposed technique uses a bimanual, planar robot manipuladum (BdF device), whose handles are grasped by the blindfolded patient: the paretic hand is passively placed in one of 17 positions and the subject is asked to actively match the paretic hand position in space with the other hand. The position sense of the paretic arm and the corresponding deficit of space representation are characterized by means of 7 indicators: 1) positional error; 2) holding force; 3) medio/lateral shift; 4) antero/posterior shift; 5) medio/lateral skew; 6) antero/posterior skew; 7) shrink coefficient. We also show how the same experimental setup can be used for "proprioceptive training", i.e. for providing robot assistance to the paretic arm that may improve the position sense of the patient. A preliminary, feasibility test has been carried out with one patient and three controls.
Journal of neuroengineering and rehabilitation, Jan 9, 2017
Several neurodevelopmental disorders and brain injuries in children have been associated with pro... more Several neurodevelopmental disorders and brain injuries in children have been associated with proprioceptive dysfunction that will negatively affect their movement. Unfortunately, there is lack of reliable and objective clinical examination protocols and our current knowledge of how proprioception evolves in typically developing children is still sparse. Using a robotic exoskeleton, we investigated proprioceptive acuity of the wrist in a group of 49 typically developing healthy children (8-15 years), and a group of 40 young adults. Without vision participants performed an ipsilateral wrist joint position matching task that required them to reproduce (match) a previously experienced target position. All three joint degrees-of-freedom of the wrist/hand complex were assessed. Accuracy and precision were evaluated as a measure of proprioceptive acuity. The cross-sectional data indicating the time course of development of acuity were then fitted by four models in order to determine which...
This work examines physiological mechanisms underlying the position sense of the wrist, namely, t... more This work examines physiological mechanisms underlying the position sense of the wrist, namely, the codification of proprioceptive information related to pointing movements of the wrist toward kinesthetic targets. Twenty-four healthy subjects participated to a robotaided assessment of their wrist proprioceptive acuity to investigate if the sensorimotor transformation involved in matching targets located by proprioceptive receptors relies on amplitude or positional cues. A joint position matching test was performed in order to explore such dichotomy. In this test, the wrist of a blindfolded participant is passively moved by a robotic device to a preset target position and, after a removal movement from this position, the participant has to actively replicate and match it as accurately as possible. The test involved two separate conditions: in the first, the matching movements started from the same initial location; in the second one, the initial location was randomly assigned. Target matching accuracy, precision, and bias in the two conditions were then compared. Overall results showed a consistent higher performance in the former condition than in the latter, thus supporting the hypothesis that the joint position sense is based on vectorial or amplitude coding rather than positional.
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Papers by Pietro Morasso