Hand dysfunction is a common symptom in stroke patients. This paper presents a robotic device which assists the rehabilitation process in order to reduce the need of physical therapy, i.e., a 3UPS/S parallel robotic device is employed for repetitive robot-assisted rehabilitation. Euler angle representation was used to solve the robot’s inverse kinematics. The robot’s joint space and rotational workspace were determined for two scenarios. In the first scenario, the workspace was obtained considering the actuator’s stroke limitations, while in the second scenario, the workspace was determined by adding a second condition, i.e., the range of motion of the spherical joints. Singularity analysis was performed using the geometric algebra approach. The robot was manufactured using additive manufacturing technology. The solution of the inverse kinematic problem was employed to control the robot. The robot can perform a full range of motion during wrist ulnar deviation and radial deviation motions, with the exception of limited wrist flexion and extension motions. The robot has singular configurations within its workspace. Although the spherical joints have roles in reducing the workspace, the primary causes are actuator selection, radii of the base and moving platforms, and the length of the central leg. These factors can be considered to improve the workspace. Singularity can be avoided by carefully selecting the rotation of the moving platform about the Z-axis and avoiding same leg lengths.

Purpose: Exoskeleton robots generally have multi-functions and one such function is doing rehabilitation therapy in upper limb and lower limb in stroke-affected patients. A novel hybrid (serial-parallel) robot manipulator was proposed in this paper for rehabilitation of upper limb and its kinematics are studied systematically. This robot manipulator intends to perform wrist flexion, wrist extension, wrist radial deviation, wrist ulnar deviation, elbow flexion, elbow extension, elbow pronation and elbow supination motions. The contemporary mechanical designs especially the kinematic structure of upper limb exoskeleton robots have a unique feature that is, almost all of them use serial manipulators, and few others used parallel manipulators. The kinematic structure of the proposed robot is that of a hybrid manipulator (two parallel manipulators connected in series) which has 4-degrees-of-freedom. It is composed of an upper 3SPS-type parallel manipulator and 2SPR-type parallel manipulator connected in series. Methods: The Jacobian and Hessian Matrix method was used to derive the manipulator kinematic formula for solving the displacement, velocity and acceleration. Results: A 3D model of the robotic arm was constructed and analyzed by simulation. The positioning workspace of manipulator was constructed and analyzed. Conclusions: The 3SPS-type parallel manipulator has good kinematic characteristics while performing wrist motions. The 2SPR-type parallel manipulator produced singular configuration, while performing the desired rehabilitation elbow motions, it was found to not be suitable for usage in performing rehabilitation therapy in stroke-affected patients.

This paper presents a novel exoskeleton robot that can be used at home to rehabilitate the index fingers of stroke-affected patients. This exoskeleton is designed as a one-degree-of-freedom four-bar mechanism able to guide the human index finger to perform a finger curl exercise motion. The proposed device is the only lateral, stand-alone mechanism built to date that can carry the weight of the human hand, thus making the user free from wearing it. The design starts by tracing the trajectory of the index finger using ‘Angulus’ software. ‘SALAR Mechanism Synthesizer’ software is used for dimensional synthesis of the four-bar mechanism. Using additive manufacturing technology, a prototype of the proposed device is developed. Static force analysis is performed to select the most appropriate actuator for producing the required torque to manipulate the fingers effectively. The kinematics of the index finger while performing a finger curl exercise is obtained. The proposed linkage mechanism can drive the index fingers of both hands. Simulation and experimental results proved the feasibility and effectiveness of the proposed design to be used for index finger rehabilitation for a wide range of users and applications by making simple minor alterations in the design. Also, a scheme for when the device can be used for rehabilitating the middle finger together with the index finger when performing flexion and extension motions is discussed.

In this paper, approaches for the solution of parallel manipulators forward kinematics have been addressed. Current research on this topic has been analyzed to determine the status and unresolved issues of the research field. Articles on parallel manipulators forward kinematics were reviewed, and numerous approaches for resolving forward kinematics in particular have been identified and published, which may assist researchers in selecting the most appropriate technique for solving the problem in this domain. Researchers have also attempted to apply these methods to a variety of other parallel manipulator-related problems, such as inverse kinematics and dynamics. In robotics, serial manipulators were invented before parallel manipulators. Hence, methodologies for solving forward kinematics were first developed for serial manipulators and many methods are ineffective for parallel manipulators. In this paper, all identified methods can be used for solving forward kinematics of parallel and serial manipulators.

In recent years, hand exoskeleton robots have attracted extensive attention from researchers and practitioners due to their potential to rehabilitate, assist, and enhance hand movements, particularly for stroke patients. With an ageing population increasingly affected by strokes, there is a growing demand for patient-centred interventions which place less demand on clinicians, especially wearable devices that can enhance hand function. Advances in artificial intelligence have opened new avenues for developing more reliable and adaptive assistive systems. This study presents a systematic literature review, following the PRISMA protocol on the design elements of hand exoskeleton robots, acknowledging the emerging perspectives on AI integration and ethical considerations. The study provides a comprehensive foundation for future research and development in rehabilitation technologies by systematically synthesising the current mechanical architecture, actuation, sensors, material, weight, and cost aspects of soft hand exoskeleton robots for rehabilitation. The results show important patterns and trade-offs in various design dimensions, providing useful information to direct the development of more accessible and efficient rehabilitation solutions in the future.

Two types of bennett mechanism are encountered in most of the related literatures. This research aims at finding the best type of bennett mechanism out of the two and then using it for suitable application. One type of bennett mechanism is known as equilateral bennett mechanism, which has all the four kinematic links of equal lengths. Next type is a bennett mechanism having their opposite links of equal length. Using the two types of bennett mechanism, two different networks are created. Their working range, minimum foldability and maximum foldability of the networks were identified using MATLAB-SimMechanics toolbox. Thus, the network having better foldability was identified, so that it can be used for making foldable tent application, which is a deployable structure. The results from the analysis prove that equilateral bennett mechanism had better foldability than its counterpart. Then on analyzing the shapes of the networks, it was found that the networks had a saddle shape. The obtained saddle surface provided certain results like, when the twist angles of the bennett links were varied, saddle surfaces with more steepness are obtained. The influence of twist angle on angular displacement, angular velocity, and angular acceleration of the mechanism were also analyzed. Singularity analysis of these networks was done in Matlab-SimMechanics simulation environment. Coupler curves for both types of bennett mechanism were plotted to identify the trajectory of the output links