1228 Part F Field and Service Robotics mechanical inputs are known.The scientific basis for 53.2.2 Movement Therapy neuro-rehabilitation remains ill-defined,with competing after Neurologic Injury schools of thought.The number of large,randomized, controlled trials that have rigorously compared different At present,much of the activity in physical therapy and therapy techniques is still small,in part because these tri- training robots has been focused on retraining movement als are expensive and difficult to control well.Therefore, ability for individuals who have had a stroke or spinal the first problem that a robotics engineer will encounter cord injury(SCI).The main reasons for this emphasis are when setting out to build a robotic therapy device is that that there are a relatively large number of patients with there is still substantial uncertainty as to what exactly these conditions.the rehabilitation costs associated with the device should do. them are high,and because these patients can sometimes This uncertainty corresponds to an opportunity to use experience large gains with intensive rehabilitation be- robotic therapy devices as scientific tools themselves. cause of use-dependent plasticity.Some systems have Robotic therapy devices have the potential to help iden- also been targeted at assisting in cognitive rehabilitation tify what exactly provokes plasticity during movement of persons with neurologic injury,as reviewed below. rehabilitation,because they can provide well-controlled A stroke refers to an obstruction or breakage of patterns of therapy.They can also simultaneously mea-a blood vessel supplying oxygen and nutrients to the sure the results of that therapy.Better control over brain.Approximately 800000 people suffer a stroke therapy delivery and improved quantitative assessment each year in the USA alone,and about 80%of these peo- of patient improvement are two desirable features for ple experience acute movement deficits [53.32].There clinical trials that have often been lacking in the past.are over 3000000 survivors of stroke in the USA, 驾 Recent work with robotic movement training devices with over half of these individuals experiencing per- is leading,for example,to the characterization of com-sistent,disabling,movement impairments.The number 53.2 putations that underlie motor adaptation,and then to of people who have experienced and survived a stroke is strategies for enhancing adaptation based on optimiza- expected to increase substantially in the USA and other tion approaches [53.5,31]. industrialized countries in the next two decades.because The second roadblock is a technological one:robotic age is a risk factor for stroke and the mean age of peo- therapy devices often have as their goal to assist in ther- ple in industrialized countries is rapidly increasing due apy of many body degrees of freedom (e.g.,the arms and to the baby boom of the 1950s. torso for reaching,or the pelvis and legs for walking). Common motor impairments that result from stroke The devices also require a wide dynamic bandwidth such are hemiparesis,which refers to weakness on one side of that they can,for example,impose a desired movement the body:abnormal tone,which refers to an increase in on a patient who is paralyzed,but also fade-to-nothing the felt resistance to passive movement a limb;impaired as the patient recovers.Furthermore,making the devices coordination,which can manifest itself as an appar- light enough to be wearable is desirable,so that the pa- ent loss in control degrees of freedom and decreased tient can participate in rehabilitation in a natural setting smoothness of movement;and impaired somatosensa- (for example,by walking over ground or working at tion,which refers to a decreased ability to sense the a counter in a kitchen),or even throughout the course movement of body parts.Secondary impairments in- of normal activities of daily living.The development clude muscle atrophy and disuse-related shortening and of high-degree-of-freedom,wearable,high-bandwidth stiffening of soft tissue,resulting in decreased passive robotic exoskeletons is an unsolved problem in robotics. range of motion of joints.Often the ability to open the No device at present comes close to matching the flex- hand,and to a slightly lesser extent close the hand,is ibility of a human therapist,in terms of assisting in dramatically decreased. moving different body degrees of freedom in a vari- The number of people who experience a SCI in the ety of settings (e.g.,walking,reaching,grasping,neck USA each year is relatively smaller-about 15 000,with movement),or the intelligence of a human therapist,in about 200000 people alive who have survived a SCI terms of providing different forms of mechanical input -but the consequences can be even more costly than (e.g.,stretching,assisting,resisting,perturbing)based stroke [53.32].The most common causes of SCI are au- on a real-time assessment of the patient's response.tomobile accidents and falls.These accidents crush the Meeting the grand challenge of robotic therapy there- spinal column and contuse the spinal cord,damaging or fore will require substantial,interrelated advances in destroying neurons within the spinal cord.The resulting both clinical neuroscience and robot engineering. pattern of movement impairment depends strongly on1228 Part F Field and Service Robotics mechanical inputs are known. The scientific basis for neuro-rehabilitation remains ill-defined, with competing schools of thought. The number of large, randomized, controlled trials that have rigorously compared different therapy techniques is still small, in part because these tri￾als are expensive and difficult to control well. Therefore, the first problem that a robotics engineer will encounter when setting out to build a robotic therapy device is that there is still substantial uncertainty as to what exactly the device should do. This uncertainty corresponds to an opportunity to use robotic therapy devices as scientific tools themselves. Robotic therapy devices have the potential to help iden￾tify what exactly provokes plasticity during movement rehabilitation, because they can provide well-controlled patterns of therapy. They can also simultaneously mea￾sure the results of that therapy. Better control over therapy delivery and improved quantitative assessment of patient improvement are two desirable features for clinical trials that have often been lacking in the past. Recent work with robotic movement training devices is leading, for example, to the characterization of com￾putations that underlie motor adaptation, and then to strategies for enhancing adaptation based on optimiza￾tion approaches [53.5, 31]. The second roadblock is a technological one: robotic therapy devices often have as their goal to assist in ther￾apy of many body degrees of freedom (e.g., the arms and torso for reaching, or the pelvis and legs for walking). The devices also require a wide dynamic bandwidth such that they can, for example, impose a desired movement on a patient who is paralyzed, but also fade-to-nothing as the patient recovers. Furthermore, making the devices light enough to be wearable is desirable, so that the pa￾tient can participate in rehabilitation in a natural setting (for example, by walking over ground or working at a counter in a kitchen), or even throughout the course of normal activities of daily living. The development of high-degree-of-freedom, wearable, high-bandwidth robotic exoskeletons is an unsolved problem in robotics. No device at present comes close to matching the flex￾ibility of a human therapist, in terms of assisting in moving different body degrees of freedom in a vari￾ety of settings (e.g., walking, reaching, grasping, neck movement), or the intelligence of a human therapist, in terms of providing different forms of mechanical input (e.g., stretching, assisting, resisting, perturbing) based on a real-time assessment of the patient’s response. Meeting the grand challenge of robotic therapy there￾fore will require substantial, interrelated advances in both clinical neuroscience and robot engineering. 53.2.2 Movement Therapy after Neurologic Injury At present, much of the activity in physical therapy and training robots has been focused on retraining movement ability for individuals who have had a stroke or spinal cord injury (SCI). The main reasons for this emphasis are that there are a relatively large number of patients with these conditions, the rehabilitation costs associated with them are high, and because these patients can sometimes experience large gains with intensive rehabilitation be￾cause of use-dependent plasticity. Some systems have also been targeted at assisting in cognitive rehabilitation of persons with neurologic injury, as reviewed below. A stroke refers to an obstruction or breakage of a blood vessel supplying oxygen and nutrients to the brain. Approximately 800 000 people suffer a stroke each year in the USA alone, and about 80% of these peo￾ple experience acute movement deficits [53.32]. There are over 3 000 000 survivors of stroke in the USA, with over half of these individuals experiencing per￾sistent, disabling, movement impairments. The number of people who have experienced and survived a stroke is expected to increase substantially in the USA and other industrialized countries in the next two decades, because age is a risk factor for stroke and the mean age of peo￾ple in industrialized countries is rapidly increasing due to the baby boom of the 1950s. Common motor impairments that result from stroke are hemiparesis, which refers to weakness on one side of the body; abnormal tone, which refers to an increase in the felt resistance to passive movement a limb; impaired coordination, which can manifest itself as an appar￾ent loss in control degrees of freedom and decreased smoothness of movement; and impaired somatosensa￾tion, which refers to a decreased ability to sense the movement of body parts. Secondary impairments in￾clude muscle atrophy and disuse-related shortening and stiffening of soft tissue, resulting in decreased passive range of motion of joints. Often the ability to open the hand, and to a slightly lesser extent close the hand, is dramatically decreased. The number of people who experience a SCI in the USA each year is relatively smaller – about 15 000, with about 200 000 people alive who have survived a SCI – but the consequences can be even more costly than stroke [53.32]. The most common causes of SCI are au￾tomobile accidents and falls. These accidents crush the spinal column and contuse the spinal cord, damaging or destroying neurons within the spinal cord. The resulting pattern of movement impairment depends strongly on Part F 53.2