The Influence of Aging on Perceptual Grouping in Haptic Search

Perceptual grouping speeds up haptic search. This has particularly been shown for grouping of distractors by similarity and good continuation [1]. Here, we investigated the effect of aging on grouping in haptic search. We reasoned that because older adults have less cognitive resources available for processing perceptual information, they would benefit more from grouping as compared to younger adults. We tested this hypothesis in a haptic search task in which proximity, similarity and good continuation of the distractors were manipulated. We found that older adults indeed show a larger effect of distractor similarity on search times as compared to younger adults, where similar dis- tractors were processed faster than dissimilar distractors. However, older adults showed an opposite effect of grouping by proximity, where items that were further apart were processed faster. This may be caused by a strong bowed spatial position effect in older adults: stimuli that are closer to each other are more difficult to discriminate. We conclude that haptic perceptual grouping by similarity has larger benefits in elderly as compared to younger adults

Adaptive fuzzy sliding mode controller design for a new hand rehabilitation robot

Hand rehabilitation is one of the most important rehabilitation procedures. Due to the repetitive nature of rehabilitation training, a full robotic system could help the physiotherapists to gain time for creating new training schemes for a larger number of patients. Such a system can be based on live or recorded data and consists of the operator-device, patient-device, and control mechanism. This paper focuses on the design of the patient-device and its control-system in a decoupled training scenario. It presents a robot for hand rehabilitation training fingers and wrist independently based on only two actuators. These two actuators are configurable to allow consecutive training on the wrist and all joints of the fingers. To overcome uncertainties and disturbances, a sliding mode controller has been designed and an adaptive fuzzy sliding mode controller is used to reduce the chattering effects and compensate the varying forces of the patients. The experimental results show an approximate 80% improvement in tracking the desired trajectory by the adaptation

Developing a new focal vibration and heat therapy system

Vibrational heating therapy is a type of physical therapy that uses the application of heat and vibrations to stimulate the body’s healing process. The therapy is believed to promote circulation, reduce inflammation, and relieve muscle tension. It is often used to treat conditions such as arthritis, fibromyalgia, and sports injuries. This paper presents the design-decisions for a device treating muscle soreness and to increase muscle strength through a combination of heat and vibration therapy to the upper leg. The system comprises farinfrared heat elements for heat transfer and two types of eccentric rotating masses (ERMs) and a linear resonant actuator (LRA) to vibrate muscle tissue. It discusses heating and vibration capability and performance. To optimize the mechanical effects of vibration therapy, the device must excite the muscle with an acceleration of more than 2 g and with a bandwidth as wide as the range of the muscle natural frequencies. For testing the heating and vibrational systems, they were tested in the same device on six different subjects with ethics permission from Technical University of Hamburg to obtain accurate results. Both ERMs were driven by DC power and yielded a bandwidth of about 30 Hz with a linear progression of acceleration over frequency, while the LRA was driven by AC power and achieved a bandwidth of about 24 Hz in the form of a bell curve. Also the selected heating element provides the desired temperature between 40 ∘C to 50 ∘C. Overall, the initial technical study showed promising measurement results and a mechanical effect in using this combination of heat and vibration therapy. As an outlook, the technical design of the next version of the device will include multiple actuators around the leg to provide more acceleration and aims to combine multiple LRAs with slightly shifted natural frequencies into one actuator module to extend the bandwidth

Development of a New Control System for a Rehabilitation Robot Using Electrical Impedance Tomography and Artificial Intelligence

In this study, we present a tomography-based control system for a rehabilitation robot using a novel approach to assess advancement and a dynamic model of the system. In this model, the torque generated by the robot and the impedance of the patient’s hand are used to determine each step of the rehabilitation. In the proposed control architecture, a regression model is developed and implemented based on the extraction of tomography signals to estimate the muscles state. During the rehabilitation session, the torque applied by the patient is adjusted according to this estimation. The first step of this protocol is to calculate the subject-specific parameters. These include the axis offset, inertia parameters, passive damping and stiffness. The second step involves identifying the other elements of the model, such as the torque resulting from interaction. In this case, the robot will calculate the torque generated by the patient. The developed robot-based solution and the suggested protocol were tested on different participants and showed promising results. First, the prediction of the impedance–position relationship was evaluated, and the prediction was below 2% error. Then, different participants with different impedances were tested, and the results showed that the control system controlled the force and position for each participant individually

Development of a new control system for a rehabilitation robot using electrical impedance tomography and artificial intelligence

In this study, we present a tomography-based control system for a rehabilitation robot using a novel approach to assess advancement and a dynamic model of the system. In this model, the torque generated by the robot and the impedance of the patient’s hand are used to determine each step of the rehabilitation. In the proposed control architecture, a regression model is developed and implemented based on the extraction of tomography signals to estimate the muscles state. During the rehabilitation session, the torque applied by the patient is adjusted according to this estimation. The first step of this protocol is to calculate the subject-specific parameters. These include the axis offset, inertia parameters, passive damping and stiffness. The second step involves identifying the other elements of the model, such as the torque resulting from interaction. In this case, the robot will calculate the torque generated by the patient. The developed robot-based solution and the suggested protocol were tested on different participants and showed promising results. First, the prediction of the impedance–position relationship was evaluated, and the prediction was below 2% error. Then, different participants with different impedances were tested, and the results showed that the control system controlled the force and position for each participant individually

Design of a Flexible mechatronic system for mechanical impedance measurement of the wrist as one step towards robotic rehabilitation

Home rehabilitation is a great complement to inpatient rehabilitation, because it allows for more regular training, especially in rural areas, where the access to physiotherapists is limited. However, unsupervised training carries the risk of deviation from the prescribed protocol. An obvious solution is to introduce a technical means for rehabilitation and continuous monitoring of performance. This paper presents a robotic system for rehabilitation of three degrees of freedom of the wrist independently, implemented with only one actuator, optimizing the design and size of the system. The device provides measurements of joint torque-position dependence, allowing objective assessment of mechanical impedance and range of motion to evaluate the progress of rehabilitation. Derived from research on haptic devices, a measurement method was implemented to measure hand impedance in the high frequency range between 100 and 200 Hz using a combination of exciters and accelerometers in the handles. This allows continuous monitoring of gripping forces without the need for complex contact-based force sensors. In collaboration between the authors’ technical and medical universities, a set of two-level passive and active safety measures was implemented to ensure the safety of the system’s users. Therefore, the presented system shows the potential to evaluate the mechanical impedance of the wrist at both low and high frequencies and to monitor the progress during rehabilitation. In the next step, a baseline of wrist impedance will be measured in a target group of healthy volunteers in order to prepare for studies in motion-restricted subjects

Guidance for the Design of Vibrotactile Patterns for Use on the Human Back

In this paper, we present an overview of parameters that are of relevance for the perception of vibrotactile patterns on the back. These patterns are delivered via varying numbers of vibration motors fixed to the back rest of a chair, vests or belts. We present recent findings from the literature about vibrotactile anisotropy, timing, spacing, anchor points, resolution and intensity. From this overview, we derive recommendations that should be considered when designing a vibrotactile device for the back. The main recommendations are: 1) Use sequential stimulation for conveying spatial patterns; 2) Avoid tactors on the spine; 3) For a rectangular grid 4 × 4 tactors seems optimal; 4) Carefully consider relative horizontal and vertical spacing. We hope that this overview will raise awareness of several issues that play a role in perception and that our recommendations will provide guidance when designing vibrotactile communication devices.</p

Haptic Feedback for Wrist Angle Adjustment

Haptic feedback is envisioned to be a powerful tool in (digital) orthosis fitment procedures. In context of a larger research project on digital molding and developing a glove for orthopedic experts, we explored the use of vibrotactile feedback on the wrist for wrist angle adjustments. Five different patterns are presented on both the inside and outside of the wrist as well as crossing signals. Participants were asked to indicate whether the pattern was communicating that the wrist angle had to be increased or decreased by moving the hand up or down. The results show that the vibrotactile stimuli are being interpreted consistently by the participants, provided the patterns are presented on one side of the arm. Although the interpretations were consistent within participants, there were individual differences in the reported directions of the signals, which makes it important to take into account personal preferences and calibration when implementing haptic feedback

The Influence of Aging on Perceptual Grouping in Haptic Search

Perceptual grouping speeds up haptic search. This has particularly been shown for grouping of distractors by similarity and good continuation [1]. Here, we investigated the effect of aging on grouping in haptic search. We reasoned that because older adults have less cognitive resources available for processing perceptual information, they would benefit more from grouping as compared to younger adults. We tested this hypothesis in a haptic search task in which proximity, similarity and good continuation of the distractors were manipulated. We found that older adults indeed show a larger effect of distractor similarity on search times as compared to younger adults, where similar dis- tractors were processed faster than dissimilar distractors. However, older adults showed an opposite effect of grouping by proximity, where items that were further apart were processed faster. This may be caused by a strong bowed spatial position effect in older adults: stimuli that are closer to each other are more difficult to discriminate. We conclude that haptic perceptual grouping by similarity has larger benefits in elderly as compared to younger adults