Touch Me, Heal Me: Haptic Solutions for Rehabilitation

The popularity of games with buzzing joysticks and consumer electronic devices with touchpads has expanded awareness of the role that haptic (touch-enabled) interfaces can play in computing applications. Yet there are other kinds of haptics that are enabling sophisticated computer-based rehabilitation solutions — “serious games” that are examples of haptics’ potential to aid clinical therapy.

The science of human touch involves multiple kinds of responses, including tactile and kinesthetic. Since touch-screen haptics, as in MP3 players and mobile phones, use tactile haptics — vibrations reacting to low-threshold mechanoreceptors in the finger pad — they do not provide input to the body on the motion and position of the limbs, or the associated forces they receive and exert.

Force feedback haptics, in contrast, involves both tactile and kinesthetic input that mimic a more comprehensive sensation of human touch. Through physical contact with the human body, haptic devices, along with haptically enabled software, exchange information with the human nervous system — both giving input to the body, and receiving input from it. Figure 1 shows a typical haptic device with a stylus that the user holds instead of a computer mouse; it pushes back on the user’s hand when it makes contact with virtual objects. Such forces can be programmed to simulate the sensation of interacting with objects that have weight — for example, retraining a stroke victim to lift a coffee mug. Haptic devices can also be programmed to simulate different material properties — for example, healthy versus diseased tissue in a palpation simulator, or depth of tool penetration when replicating a needle injection to draw blood.

In the last two years, uses for force feedback haptics have grown beyond research demonstrations of viability and one-off simulators to include many more commercially available touch-enabled therapeutic solutions and medical training simulators. The reason for this has less to do with the popularity of joysticks and touchscreens than dramatic advances in haptic programming, coupled with more affordable haptic devices. The science of touch-enabling an application demands hardware and software that enable users to “feel” what they see on-screen. Haptics programming used to be quite specialized, difficult, and time-consuming. Now, readily available software development toolkits allow professionals with even a passing familiarity with C++ programming to quickly prototype their ideas and touch-enable either new or existing computer applications. The result is that medical solutions developers can create more useful products that integrate a highly realistic sense of touch and deliver a more compelling user experience.

Curictus: “Serious Games” for Stroke Rehab

The Curictus Virtual Rehabilitation System (VRS) uses haptics to stimulate patients’ awareness of their own resources and difficulties, as well as their interests and creativity. The solution, created by Curictus of Gothenburg, Sweden, won the Healthcare IT Award from the medical trade publications Dagens Medicin and Computer Sweden, in part for its ability to add a sense of touch to computer-based rehabilitation.

Stroke victims often need extensive practice to retrain the muscles of the arm and hand to perform everyday tasks and exercise the brain to help restore functionality. They can become frustrated by their limitations to perform the simplest of tasks. Some patients, particularly older men, may scoff at certain clinic-based occupational therapy tasks, such as crafts and kitchen-related activities — yet delight when asked to perform similar types of exercises by “playing on the computer.”

Curictus VRS includes a computer, 3D stereoscopic monitor, a PHANTOM® haptic device from SensAble Technologies (Wilmington, MA), and a half-silvered “immersive” mirror that can be used either at the patient’s home or clinic; it has been clinically proven to improve user performance. Patients also wear special 3D glasses so they can see the 3D graphics on the mirror display. (Fig. 2)

Therapists select from 14 games, ranging from archery and fishing to mental arithmetic, designed with the older stroke population’s needs in mind and focusing on touch-and-arm/hand-motor functions such as reaching, hand-eye coordination, transport with precision, attention, concentration, problem solving, and working memory (Fig. 3). Games require the patient to perform reaching movements, as dictated by the target (game element) locations in 3D space. The haptic device provides the patient with varying degrees of “push back” or force feedback for a given task.

APIs Dramatically Simplify Touch-Enabling

Curictus’s engineers touch-enabled the VRS system using the SenseGraphics H3DAPI, an application programming interface (API) from SenseGraphics that lets developers quickly create multisensory applications. Haptically enabled APIs such as SenseGraphics H3DAPI and SensAble’s QuickHaptics® micro API allow fast prototyping and development, since programming tasks require dramatically fewer lines of software code. With SenseGraphics H3DAPI and the use of Python scripting (a popular and easy-to-use scripting language) Curictus developers were able to quickly create a large suite of games ready for user testing and evaluation. With QuickHaptics, a simple application to touch and manipulate a 3D model can be written with just eight lines of programming code, instead of hundreds. These APIs and their top-down design with haptics applications in mind make it easy for any programmer who has used fundamental programming languages like XML and OpenGL to begin writing touch-enabled applications.

For example, in the “Mug MasterMind” game (Fig. 4), the objective is to find the correct color combination by placing coffee mugs on a shelf — so the room environment is haptically enabled. Developers assigned a different “feeling” for the weight of the mugs for carrying them from the start and end locations in the room, and for the shelf positions (top versus bottom). General difficulty settings — easy, medium, and difficult — allow a therapist to make detailed adjustments to guide the patient’s recovery.

The Advantages of Computer-Based Rehabilitation Solutions

Clinical experience has confirmed that haptically enabled virtual reality games can become a capable adjunct to personal sessions with a clinician. In one example, a 62-year-old truck driver who had never used a computer before became so enamored with Curictus VRS’s tennis module that he quickly learned to score 2,100 points per game. During his next therapy session, when guided by his therapist, he improved his game performance during that one session alone by an additional 2,300 points. In contrast, simply playing an off-the-shelf consumer game on a platform would not deliver exactly the right level of forces that the patient needs, nor would it increase forces as patients recover their strength and skills.

Additionally, Curictus offers an optional Activity Management Center that logs effective training time and various performance parameters and allows the therapist to access them remotely via the Internet at any time.

While it may be years before the dictum “Patient, Heal Thyself” becomes a reality, touch-enabling computer-based rehabilitation solutions may be the next best thing in offering patients an innovative way to take a more active and committed role in their own rehabilitation.

This article was written by Dr. David Chen, Chief Technology Officer for SensAble Technologies in Wilmington, MA. Contact Dr. Chen at 781-937-8315 or This e-mail address is being protected from spambots. You need JavaScript enabled to view it , or visit http://info.hotims.com/34450-135.