Types of robotic rehabilitation and their applications

Robotic technology can provide service, body support, unweighting, and movement assistance that is passive, active, variable, and on-demand assistance. ^, Computerized and robotic technology provides the foundation for patients to practice and attend to purposeful, goal-oriented, progressive tasks spaced over time. This technology can also minimize the risk of injury during retraining. Robotic rehabilitation devices may include service robots, nonwearable assistive robotic devices, wearable assistive robotic devices, or neuromuscular stimulators. There are also vocational rehabilitation robotics, communication devices, and emotional interactive entertainment/friendly robots, which will not be investigated in depth in this chapter. Fig. 38.1 and Box 38.1 provide an overview of the classifications of robotics technology.

Classification of Rehabilitation Technology.

Service robots usually focus on task performance, movement assistance, and stability. These devices can be fixed, movable, or attached to a wheelchair. Assistive robotic devices help patients perform a task with direct or indirect assistance. Some of the assistive robotics are nonwearable but assist through unweighting or movement assistance. Wearable robotic devices are specifically designed to be worn by patients to assist movements. These are designed for the upper or lower limb. Vocational robotics can enhance performance at work either in terms of repetitive motions or high-force task production that would otherwise be dangerous to humans. Communication robotic devices are designed to improve communication potential for patients who cannot adequately speak or hear. Emotional support robotic devices are designed to provide emotional support for isolated individuals at home.

Prosthetics for amputees, vocational robotics, communication robotics, emotional support robotics, or socially assistive devices are not outlined in detail here as these areas are considered specialty oriented and may or may not be included in traditional neurorehabilitation programs coordinated by physical or occupational therapists.

For simplicity, we will focus on our examination on service robots, nonwearable assistive robotic devices, and wearable assistive robotic devices. It is also important to acknowledge there are a number of motorized chairs, lifts, and walkers available that can be used to transition a patient from sitting to standing, or provide unweighting while walking, or working on balance. These devices are not usually programmable and are not classified as “rehabilitation robotics” or “advanced technology.” However, these types of devices are very beneficial for helping patients maintain walking and training to improve safety and quality of gait at home and with supervision. It is important for therapists to be sure these types of assistive devices have been considered and/or integrated into a patient’s rehabilitation program and at home before recommending more sophisticated technology.

Service robotics

Service robots primarily assist individuals with severe disabilities. Most commonly, the robot performs everyday activities (e.g., assisting with eating, drinking, object replacing, ambulating). There are three main types of schemes: desktop-mounted robots, wheelchair-mounted robots, and mobile autonomous robots. In general, these robots are used in the home, are interconnected to a variety of control systems, are programmed to the environment and consequently are not very portable.

These types of robotic devices are often preprogrammed to perform certain tasks. There are also some autonomous robots in which the cognitive interface between the user and the robot is used to tell the robot to perform a new task or to help the patient perform the task. These robotic systems are successful if the robot, the user, and the manipulated objects remain in the same initial set position every time a concrete task is performed. With the wheelchair-mounted manipulator, the relative position of the user with respect to the manipulator needs to remain the same. Although there are a variety of simple service-based robotic devices, most are complex, and setting them up at home generally requires a computer or engineering specialist.

Service robots may include smart wheelchairs and smart devices in the home (e.g., The Robotic Room ) or wheelchair-mounted upper extremity manipulators. A major consideration for patients using service robotic devices are the control options. For example, through the use of headpieces on robotic devices, information can be detected from flexion and extension, rotation, and side bending of the head to operate wheelchairs, TV sets, telephones, doors, and security systems. There are also interfaces that are sensitive to facial movements and optoelectronic detection of light-reflective head movements. Other interfaces are sensitive to eye movements or use voice recognition, brain control, ^, and gesture recognition. These interfaces not only may allow control of the robot but also may be applied to move a limb or perform a task. A more detailed discussion of robotic interfaces is included later in this section.

Service robotics is recommended when patients have achieved their maximum potential and still need assistance to live independently. A therapist may continue to work with a patient at home to maintain range of motion, minimize skin problems, and review whether the robotic technology is still providing the necessary assistance. However, an engineer will usually assume the primary responsibility for maintaining and adjusting the robotic equipment.

Nonwearable assistive robotic devices

This group of robotic devices primarily includes powered wheelchairs with autonomous intelligence, robots for body support, and hands-off service robotic devices. Body weight supported treadmill systems (BWSTSs) with and without robotics and body weight-support mobile walking aids (BWSMWA) are also aligned to this category. ^, The value of BWSTSs and similar nonwearable assistive robotic devices is that patients can be supported to develop their body structures and functions (e.g., step length, weight shift abilities, balance) as a precursor to practicing tasks at the activity/participation level in more authentic, natural settings. Body weight–supported gait training systems were initially designed to unweight the body, decrease ground reaction forces (GRFs), and protect against falling ( Fig. 38.2 ). Under these assisted conditions, it is easier for patients to achieve intense levels of exercise such as walking, skipping, and running with less pain and less trauma to the joints.

Body weight–support trainer or body weight supported treadmill trainer: Lokomat robotic system.

(Courtesy Hocoma, Volketswil, Switzerland.)

Assistive robotic devices hold a prominent place in the rehabilitation of adults and children with neurological dysfunction. ^, Robotic-assisted BWSTT has been investigated for individuals with chronic spinal cord injury and stroke. Evidence of greatest efficacy of these robotic or electromechanical-assisted devices has been reported in the first 3 months following stroke, and of most benefit to those with very limited walking ability. Furthermore, it is important to support patients to walk at community-level velocities of at least 0.8 m/s (faster than 2.0 mph). Devices such as the Lokomat, which robotically augment joint placement and walking execution on a treadmill, have been examined in children with neurological impairments. Children with cerebral palsy may experience greatest benefit when they have moderate-to-severe degrees of gait impairment (e.g., GMFCS levels II, III, and IV). The opportunity for clinically noticeable training change is greatest and more likely to achieve physiological and possibly neuroprotective benefits. ^,

Nonwearable assistive robotic devices can offer patients the potential for high degrees of repetitive practice by adjusting, placing, and guiding the limb through repeated movements. ^{, ,} It can help reduce the taxing physical effect and awkward positioning of rehabilitation on clinicians while offering even higher volumes of practice in a single session. However, at some point, clinicians and patients must face the possibility of a ceiling effect of high-dose practice in a predictable environment. The therapeutic course should take the patient to eventually progress to task-specific training outside of assistive robotic devices, which is where conventional approaches to therapy take precedence.

Wearable assistive robotic devices

Assistive robotic devices are also popular in upper limb rehabilitation. The upper limb is highly complex, with a requirement for devices to be appropriately light and responsive to degrees of movement. The shoulder and hand/wrist will demand multidimensional options compared to the elbow. This becomes challenging for designers to balance aligning the device with joints, as well as incorporating motors, actuators, and cabling. The clinician will therefore decide whether the patient requires an exoskeleton device (e.g., Armeo) with torque actuators that control single/multiple joints, or an end-effector-type device (e.g., InMotion 2.0), which focuses on the distal portion of the upper limb. A recent study on post-stroke intervention notes a higher degree of exploration of end-effector devices as newer exoskeleton technologies have been less commonly investigated. It also notes that meaningful change, especially with earlier intervention, will be assisted with some degree of voluntary muscle initiation of wrist and fingers; timing of intervention remains an important consideration.

Wearable assistive robotic devices can support patients to participate in everyday tasks with greater autonomy. Structures may be exoskeleton but with rigid or soft wearable features. They may be fixed in place in a clinical training station or they may allow great portability with movement and use. Examples of these include the ironHand system or those that are triggered with neuromuscular stimulation, such as the Bioness upper limb or lower limb systems (see Fig. 38.3 ). The primary impairment that can be addressed with neuromuscular stimulation is muscle weakness, but the patient may also have neuromotor control problems or abnormal synergies of movement. These devices work only when peripheral nervous system function is preserved. The electrodes, located within the device’s control unit, stimulate a peripheral nerve causing a movement effect. However, in the case of patients with spinal cord injuries, multiple electrodes may need to be used to sequentially activate a series of muscle contractions to enable walking. Similar robotic devices and principles of operation are available for patients post-stroke.

Wearable Upper-Limb Devices and Assistive Robotic Exoskeleton Devices.

(A) Myomo upper-limb robotic assistive device. (B) Bioness L200 arm and wrist trainer. (C) Shoulder, elbow, and wrist upper-limb assistive robotic bilateral device. (D) Armeo robotic arm.

(A, Courtesy Myomo, Cambridge, MA. B, Courtesy Bioness, Valencia, CA. C, Courtesy Jacob Rosen/Jim Mackenzie, UCSC. D, Courtesy Hocoma, Volketswil, Switzerland.)

Wearable assistive robotic technology extends, complements, empowers, replaces, or enhances the function or capability of the individual. For some patients, using these is an ongoing component of their rehabilitation. For others, the wearable assistive robotic device is used as it can complete the action of a task that is no longer an effective or efficient option for the patient. These robotic devices may facilitate muscle contractions in one or more directions around one joint such as the elbow, wrist, or ankle. The objectives of reducing muscular fatigue and energy conservation during task practice are met when devices are lightweight, flexible, sensitive to movement change, and easily portable. ^{, ,}

Upper limb and lower limb wearable robots are obviously worn by the individual, but the internal or external interface must be mapped to the anatomy, a cognitive control mechanism, or the brain. The extremities can be used to perform multiple tasks, and the redundancy of the joints and degrees of freedom (e.g., at the ankle, or the wrist) allow people to perform tasks in a variety of ways. Redundancy of the joints and degrees of freedom allow a variety of ways patients can perform a task; however, these redundancies may be hard to control. Wearable robotic devices will vary by type of human interface system incorporated (e.g., brain neurons, cognitive, sensory [tactile, pressure], physical [movement], or breath). At a minimum, the physical interface of a wearable robot requires an actuator and a rigid structure to transmit forces to the neuromusculoskeletal system.

Ideally, wearable systems use both muscle stimulation and active voluntary muscle contractions to increase functional use. Devices such as the ReWalk and the Hybrid Assistive Limb (HAL) are well known commercially, and among clinicians working in neurological rehabilitation, for their wearable design and capacity to support patients with spinal cord injuries particularly, to ambulate with relative independence. With actuation componentry at the hip and knee, these devices facilitate gait with electromyographic triggered stimuli (HAL) or battery powered, remote-control operation mechanisms (ReWalk). As with the upper limb orthoses though, wearable exoskeleton technologies guiding lower limbs have key limitations around their size, bulk, weight, and responsiveness to the external environment. There can be some limitations in transferring the device usage into more complicated, unpredictable terrains. However, as a concept, wearable lower limb exoskeletons such as the ReWalk and HAL can have significant influence at the activity and participation level. If accessible to rehabilitation staff, they may be worthy of consideration for goals that align to these dimensions of the WHO-ICF. Other device examples recently cited in the literature include Ekso exoskeleton, REX Personal, and the Indego exoskeleton.

Robotic system mechanisms for operation

Robotic interfaces, actuators, and controllers can convert sensory, physical, and cognitive signals to:

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  control robots

  
  
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  permit perception of spatial relationships

  
  
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  mobilize individuals in space

  
  
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  assist in object manipulation

  
  
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  provide emotional support

  
  
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  allow individuals to call for help and communicate with others

In addition, through creative virtual training environments and gaming technology, patients can improve memory, motor skills, and movement quality.

Different robotic designs enable different performance outcomes. Understanding robotic mechanisms of operation is an important first step for a clinician as it may guide the selection of devices for patients. Robotic devices in general may be active, passive, haptic, or predominantly performance feedback-oriented. ^, The degree of assistance offered will determine the suitability of robotic mechanical design, and vice-versa. Maciejasz and colleagues best summarized different robotic systems by feature, outlined in Table 38.2 .

The robotic device’s mechanical design (e.g., exoskeleton) also has specific properties, which may require some understanding. These properties can help determine the degree of augmented movement available in the device, ^, as outlined in Table 38.3 .

Clinical rationale for the use of robotic devices is specific to the patient and the particular device. Robotic devices can be used to improve body structure and function, activities, and participation. For example, the Lokomat (see Fig. 38.2 ) uses a body weight–supporting exoskeleton and provides augmented limb movement to improve the functions of weight-bearing tolerance and sagittal plane joint mobility. ^, Other devices, such as the ReWalk ( Fig. 38.4 ), support the spinal cord-compromised patient to ambulate with crutches, allowing community mobility and potentially greater autonomy ; performance factors that align with “participation” expectations. Patients in early rehabilitation phases may respond better to a particular type of robotic device, superseded by an alternative option as the patient’s capabilities evolve or diminish. There also may be changes between genuine neurological structure recovery (e.g., CNS reactivation) and the emergence of effective compensatory strategies for movement. Iosa and colleagues have recently proposed the “ideal” interactional loop between the patient, the rehabilitation professional, and the robotic rehabilitation device selected ( Fig. 38.5 ).

Re-Walk Personal 6.0.

Interactional Loop Between Robotic Device, Patient, and Therapist. ^{, (p. 8)}

Aligning the device category, actuation componentry, design, and function to the patient’s needs can confidently provide the clinician with a plan for robotic application. Many therapists will be limited by what their workplace has access to.