A new wrist exoskeleton prototype was developed to advance upper limb rehabilitative technology by achieving three degrees of freedom: radial/ulnar deviation, flexion/extension, and pronation/supination. Unlike most commercial devices, which typically provide only two degrees of wrist motion, this design incorporates a gear-driven rotational apparatus to introduce pronation and supination. The mechanism features a stable base, robust structural components, and prioritizes user safety, practicality, and functionality.

The final mechanism uses three CubeMars AK80-9 motors to directly actuate each degree of freedom. An ESP32 microcontroller, integrated with a CAN module, enables real-time communication and control via C++ programming in Visual Studio Code. Safety was ensured by tuning motor parameters and implementing motion limits based on Fourier series calculations, which were iteratively refined to reduce injury risk while maintaining effective movement.

The system achieves motion ranges of 15° for radial/ulnar deviation, 75° for flexion/extension, and 105° for pronation/supination. FDM 3D printing with PETG-CF materials reduced fabrication costs while maintaining structural integrity, verified through CAD modeling and FEA simulations. The user interacts with the mechanism by gripping a central handle, which moves responsively through coordinated motor control, providing accessible and effective wrist rehabilitation for users recovering from injury or seeking to improve dexterity.

A new iteration of the hand exoskeleton prototype was designed and developed based on a mechanical synergy design, which used two actuators to operate the three finger groups. This design allowed for our exoskeleton to significantly reduce the number of actuators required, from five to two. As a result, the weight and cost of the device are also reduced.

Two main provided synergies were identified from the literature on hand anatomy, and three finger groups are specified as the pinky and ring fingers (Group 1), the middle and index fingers (Group 2), and the thumb finger (Group 3). The developed hand exoskeleton has two linear actuators to move these finger groups, which allows for the grasping motions of the hand, powered by an outside power source. The mechanism was validated through FEA study and tested experimentally with FDM 3D printed components with PETG-CF material.

The Hand exoskeletons will aid in reducing the cost of physical therapy since users can perform movements without the need for a physical therapist’s assistance and provides routine or therapeutic exercises.

Team member: Ashely Huang, Perla Portillo, Ezekiel John Saldajeno

This hand exoskeleton prototype was designed and developed, representing an assistive device for post-stroke patients and individuals requiring hand rehabilitation. Flex sensors were integrated into a soft glove, enabling precise and intuitive control of the exoskeleton in response to natural finger movements. This user-friendly and patient-centric mechanism ensures a wide range of motion to mirror the exact movements of the user's opposite hand or the therapist's hand. This has the potential to enhance the effectiveness of assistance and rehabilitation strategies. 

Controlled with a sensorized soft glove (SSG), the designed hand exoskeleton focused on user-centric attributes, including lightweight construction, durability, and comfort. The constructed hand exoskeleton leverages printable finger segment mechanisms and other lightweight components, enhancing replicability.

The mechatronic system, featuring flex sensors and micro linear actuators, adopts a modular design, streamlining setup, storage, troubleshooting, and component replacement. A central microcontroller-driven main board ensures immediate communication between flex sensors on the soft glove and actuators on the hand exoskeleton, facilitating replication of individual finger flexion and extension movements.

Examinations that encompassed various hand configurations and movements, validated the exoskeleton’s performance across individual finger movements, with rotational movement's root mean squared error (RMSE) less than 9.03 degrees between the actual and desired trajectories. 

Team member: Yoseph Chaka, Perla Portillo, Ezekiel John Saldajeno, Rubin Gonsalves

A linkage-based shoulder-elbow exoskeleton was designed and developed to improve the design of an existing portable upper limb exoskeleton by adding more actuated DOF and improving weight and mechanism complexity without compromising performance. 

This design utilized a total of four DOFs with three dedicated to the shoulder joint and one for the elbow joint. The three main assemblies that make up the composition of the exoskeleton are the main linkage for the forearm and upper arm, the gimbal mechanism, and a motor assembly arranged on a carbon fiber back plate. Utilizing telescopic aluminum bars, the links were able to be adjusted to accommodate different body types. A combination of Bowden cables and pulleys was used to reduce the inertia and weight of moving parts. The structural integrity of the exoskeleton was validated by performing Finite Element Analysis (FEA) for applied loading and fatigue on what were deemed critical components: pulley housing, backplace cable housing, and the angled links. Assembly was manufactured with thermoplastic using FDM 3D printing method and aluminum bars using CNC and manual milling methods, or purchased and cut into length. 

The exoskeleton comprised three main assemblies: the main linkage for the forearm and upper arm containing pulleys and cable mounts attached to provide the necessary movement to each individual joint, the back plate assembly, connecting the joints to the motors with Bowden cables, shaped and designed to be ergonomic and comfortable, and lastly, the gimbal mechanism that served as a connection link between the first two assemblies and provided the desired movement of the arm. The new design aimed to add more degrees of freedom to the previous upper limb exoskeleton while being as light as possible without compromising performance.

Team members: Andrew Truong, Sannad Shabbar

A lightweight and adjustable upper limb exoskeleton has been designed and developed to assist individuals with mobility impairments resulting from spinal injuries or strokes. This exoskeleton offers mobility assistance for elbow and shoulder movements, addressing the rehabilitation needs of patients.

The design is focused on being lightweight, adjustable, affordable, and suitable for individuals of varying body types. Each joint is designed as an adjustable revolute joint providing a full range of motion with a single actuated degree of freedom (DOF). The arm of the exoskeleton is designed as a prismatic joint to allow length adjustment of each link. Motors are situated on the body and actuate each joint with Bowden cables and pulleys. The mechatronic system utilizes an ESP32 microcontroller, a T-motor AK80-9 motor, and an MPU 6050 accelerometer sensor. The motors use CAN communication with minimal communication latency that provides efficient real-time movements of the motor. The backpack-style design reduces the device's overall size and weight.

Materials used to manufacture the components were polyethylene terephthalate glycol (PETG) and thermoplastic polyurethane (TPU) with the FDM 3D printing method. Steel and aluminum materials were used for the pulley shafts and outer links. Carbon Fiber and High-density Polyethylene (HDPE) components are utilized in high-stress areas.

The upper limb exoskeleton offers an effective and affordable solution for rehabilitation in cases of spinal cord injuries and post-stroke conditions. It provides mobility assistance across all ranges of motion, accelerating recovery and improving the quality of life for users.

Team members: Nathanael Lacuata, Brandon O'dell, Anthony John

For this lightweight upper limb exoskeleton, a semi-rigid chain has been designed to address the misalignment issue of the body joint movements. The joints were adapted to the motors that are situated on the body, actuating joints with Bowden cables and pulleys. The degrees of freedom (DOFs) are abduction-adduction and flexion-extension of the shoulder and flexion-extension of the elbow. 

Based on the FEA analysis performed, the chosen material used for the semi-rigid chain design was carbon fiber-infused polyethylene terephthalate glycol (PETG-CF) for critical components and thermoplastic polyurethane (TPU) for areas interacting with the user that requires a flexible material for comfort. The parts were manufactured using the FDM 3D printing method.

The cable-driven upper limb exoskeleton provides an alternative actuation method as a proof-of-concept that can be further developed to provide a lighter-weight exoskeleton used for human assistance in various strenuous tasks or for rehabilitation purposes.

Team member: Yu Xian Lim