Frame-Based Slip Detection for an Underactuated Robotic Gripper for Assistance of Users with Disabilities

Stable grasping is essential for assistive robots aiding individuals with severe motor–sensory disabilities in their everyday lives. Slip detection can prevent unstably grasped objects from falling out of the gripper and causing accidents. Recent research on slip detection focuses on tactile sensing; however, not every robot arm can be equipped with such sensors. In this paper, we propose a slip detection method solely based on data collected by a RealSense D435 Red Green Blue-Depth (RGBd) camera. By utilizing Farneback optical flow (OF) to estimate the motion field of the grasped object relative to the gripper, while also removing potential background noise, the algorithm can perform in a multitude of environments. The algorithm was evaluated on a dataset of 28 daily objects that were lifted 30 times each, resulting in a total of 840 frame sequences. Our proposed slip detection method achieves an accuracy of up to 82.38% and a recall of up to 87.14%, which is comparable to state-of-the-art approaches when only using camera data. When excluding objects for which movements are challenging for vision-based methods to detect, such as untextured or transparent objects, the proposed method performs even better, with an accuracy of up to 87.19% and a recall of up to 95.09%.</p

Combining robotics and functional electrical stimulation for assist-as-needed support of leg movements in stroke patients:A feasibility study

Purpose: Rehabilitation technology can be used to provide intensive training in the early phases after stroke. The current study aims to assess the feasibility of combining robotics and functional electrical stimulation (FES), with an assist-as-needed approach to support actively-initiated leg movements in (sub-)acute stroke patients. Method: Nine subacute stroke patients performed repetitions of ankle dorsiflexion and/or knee extension movements, with and without assistance. The assist-as-needed algorithm determined the amount and type of support needed per repetition. The number of repetitions and range of motion with and without assistance were compared with descriptive statistics. Fatigue scores were obtained using the visual analogue scale (score 0–10). Results: Support was required in 44 % of the repetitions for ankle dorsiflexion and in 5 % of the repetitions of knee extension, The median fatigue score was 2.0 (IQR: 0.2) and 4.0 (IQR: 1.5) for knee and ankle, respectively, indicating mild to moderate perceived fatigue. Conclusion: This study demonstrated the feasibility of assist-as-needed assistance through combined robotic and FES support of leg movements in stroke patients. It proved particularly useful for ankle dorsiflexion. Future research should focus on implementing this approach in a clinical setting, to assess clinical applicability and potential effects on leg function.</p

On the tip of the tongue: Learning typing and pointing with an intra-oral interface

Purpose: To evaluate typing and pointing performance and improvement over time of four able-bodied participants using an intra-oral tongue-computer interface for computer control. Background: A physically disabled individual may lack the ability to efficiently control standard computer input devices. There have been several efforts to produce and evaluate interfaces that provide individuals with physical disabilities the possibility to control personal computers. Method: Training with the intra-oral tongue-computer interface was performed by playing games over 18 sessions. Skill improvement was measured through typing and pointing exercises at the end of each training session. Results: Typing throughput improved from averages of 2.36 to 5.43 correct words per minute. Pointing throughput improved from averages of 0.47 to 0.85 bits/s. Target tracking performance, measured as relative time on target, improved from averages of 36% to 47%. Path following throughput improved from averages of 0.31 to 0.83 bits/s and decreased to 0.53 bits/s with more difficult tasks. Conclusions: Learning curves support the notion that the tongue can rapidly learn novel motor tasks. Typing and pointing performance of the tongue-computer interface is comparable to performances of other proficient assistive devices, which makes the tongue a feasible input organ for computer control

TongueWise : tongue-computer interface software for people with tetraplegia

Many computer interfaces and assistive devices for people with motor disabilities limit the input dimensionality from user to system, in many cases leading to single switch interfaces where the user can only press one button. This can, either limit the level of direct access to the functionalities of the operating system, or slow down speed of interaction. In this paper we present TongueWise: a software developed for a tongue computer interface that can be activated with the tip of the tongue and that provides direct input that covers most of the standard keyboard and mouse commands

Using workspace restrictiveness for adaptive velocity adjustment of assistive robots and upper limb exoskeletons

Individuals with severe disabilities can benefit from assistive robotic systems (ARS) for performing activities of daily living. However, limited control interfaces are available for individuals who cannot use their hands for the control, and most of these interfaces require high effort to perform simple tasks. Therefore, autonomous and intelligent control strategies were proposed for assisting with the control in complex tasks. In this paper, we presented an autonomous and adaptive method for adjusting an assistive robot's velocity in different regions of its workspace and reducing the robot velocity where fine control is required. Two participants controlled a JACO assistive robot to grasp and lift a bottle with and without the velocity adjustment method. The task was performed 9.1% faster with velocity adjustment. Furthermore, analyzing the robot trajectory showed that the method recognized highly restrictive regions and reduced the robot end-effector velocity accordingly.Clinical relevance - The autonomous velocity adjustment method can ease the control of ARSs and improve their usability, leading to a higher quality of life for individuals with severe disabilities who can benefit from ARSs.</p

Usability of the inductive tongue computer interface:Internet use, speaking, and drinking - Evaluated by two users with disabilities

Tongue computer interfaces have shown promising for both computer control and for control of assistive technologies and robotics. Still, evidence is lacking in relation to their usability resulting in speculations on their effectiveness for general computer use and their impact on other activities such as speaking, drinking, and eating. This paper presents the results of such a usability study performed with two individuals with tetraplegia. The results show a high acceptance of the Inductive Tongue Computer Interface with an average rating of 2.6 on a scale from 1 (normal) to 10 (unacceptable) and a low impact on speech after only 3 days of use.Clinical Relevance - This study emphasizes the applicability and adoptability of the Inductive Tongue Interface as a useful assistive technology for individuals with severe disabilities.</p

Simulation-based design optimization of a wrist exoskeleton

Exoskeletons are widely used in the field of rehabilitation robotics. Upper limb exoskeletons (ULEs) can be very useful for patients with diminished ability to control their limbs in aiding activities of daily living (ADLs). The design of ULEs must account for a human's limitations and ability to work with an exoskeleton. It can typically be achieved by the involvement of vulnerable end-users in each design cycle. On the other hand, simulation-based design methods on a model with human-in-the-loop can limit the design cycles, thereby reducing research time and dependency on end users. This study makes it evident by using a case where the design of an exoskeleton wrist can be optimized with the usage of a torsional spring at the joint, that compensates for the required motor torque. Considering the human-in-the-loop system, the multibody modeling results show that the usage of a torsional spring in the joint can be useful in designing a lightweight and compact exoskeleton joint by downsizing the motor.Clinical Relevance - The proposed methodology of designing an upper-limb exoskeleton has a utility in limiting design cycles and making it both convenient and useful to assist users with severe impairment in ADLs.</p

Development of inductive sensors for a robotic interface based on noninvasive tongue control

Tongue based robotic interfaces have shown the potential to control assistive robotic devices developed for individuals with severe disabilities due to spinal cord injury. However, current tongue-robotic interfaces require invasive methods such as piercing to attach an activation unit (AU) to the tongue. A noninvasive tongue interface concept, which used a frame integrated AU instead of a tongue attached AU, was previously proposed. However, there is a need for the development of compact one-piece sensor printed circuit boards (PCBs) to enable activation of all inductive sensors. In this study, we developed and tested four designs of compact one-piece sensor PCBs incorporating inductive sensors for the design of a noninvasive tongue-robotic interface. We measured electrical parameters of the developed sensors to detect activation and compared them with a sensor of the current version of the inductive tongue-computer interface (ITCI) by moving AUs with different contact surfaces at the surface of the sensors. Results showed that, the newly developed inductive sensors had higher and wider activation than the sensor of ITCI and the AU with a flat contact surface had 3.5 - 4 times higher activation than the AU with a spherical contact surface. A higher sensor activation can result in a higher signal to noise ratio and thus a higher AU tracking resolution

The impact of an underactuated arm exoskeleton on wrist and elbow kinematics during Prioritized Activities of daily living

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