Arm Robot

Development of a low-cost training robot for home-based rehabilitation to promote motor recovery of the hemiparetic upper extremity for patients after stroke

開發低成本居家復健訓練機器人，促進中風後偏癱上肢運動恢復

Principal Investigator: Prof. FONG Nai Kuen, Kenneth, Department of Rehabilitation Sciences

Project Objectives

The overall aim of the project is to develop a portable and low-cost training robot for the hemiparetic upper extremity for patients with stroke for the purpose of home-based rehabilitation. The objectives of this project are:

1. To design and develop a portable and low-cost rehabilitation robot for the hemiparetic upper extremity for patients with stroke for the purpose of home-based rehabilitation, in the form of prototyping and mini production;
2. To carry out a proof-of-concept clinical trial to explore the usability of the novel training robot developed in this project with conventional rehabilitation treatment and control for patients with stroke in Hong Kong.

Project Methodology

Traditionally, there are three types of training robots:

1) wheeled-driven end-effector based (W-EE, left in Figure 1);

2) arm-driven end-effector-based (A-EE, middle in Figure 1); and

3) exoskeleton-based (Exoskeleton right in Figure 1). 

The kinematic model of W-EE robots will be simpler since there are no serial connections. The dynamic model of W-EE robots’ structure is run in a planer space, the rotation about the z-axis can be neglected.  Considering that the EE robots are better effects than the exoskeleton robots [10], and considering their portability, size, easy-to-use, and cost, we decide to develop a powered skateboard-like arm robot similar in outlook to the manual skateboard commonly used by occupational therapists for patients to use at home or clinic (Figure 2).

In designing our home-use robot, there are 4 pillars to be considered: 1) safety, 2) clinical efficacy, 3) human-technology interface, and 4) cost-effective, drawing on the Human Activity Assistive Technology (HAAT) Model. The robot aims to support the forearm, be compact and lightweight, and provide interactive mechanisms to assist with different stages of motor recovery as outlined in the Brunnstrom stages of motor recovery theory.

In sum, our design should include: (a) the mechanical and material structures should be chosen to fulfil the low weight and low cost requirements, and fit for home use; (b) the mechatronics system design in the robot should be optimized to allow portable and lightweight rehabilitation robot; (c) the control strategies specified for the robot kinematics should be devised to allow rehabilitation strategies for different stages of motor recovery of the hemiparetic arm according to the Brunnstorm stages of motor development.

The initial design of the robot is shown in Figure 3.

Fig3. Initial design of arm robot

Project Research Plan

The overall methodology combines engineering system design and user-centric design paradigms in order to align them in the project. The engineering system design paradigm focuses more on the development and justification of robotic system to meet the two aforementioned issues, while the user-centric design paradigm will be used to keep the robot clinical feasible and user friendly

The deliverables of our project are (Timeline: Months 0–12):

1. R&D of the rehabilitation robot
2. Prototyping the rehabilitation robot
3. Mini-production of 6 pieces
4. Pilot trial on end-users
5. Patent filing
6. Revision of R&D and prototyping
7. Output dissemination

References:

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[2] Thematic Household Survey Report No.50. Health Status of Hong Kong Residents. Hong Kong SAR: Census and Statistics Department; 2013.

[3] Jørgense HS, Nakayama H, Raaschou HO, et al. Functional and neurological outcome of stroke and the relation to stroke severity and type, stroke unit treatment, body temperature, age, and other risk factors: The Copenhagen stroke study. Top Stroke Rehabil 2000;6:1-19.

[4] Kwakkel G, Kollen BJ. Predicting activities after stroke: What is clinically relevant? Int J Stroke 2013;8(1):25-32.

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[10] Lee SH, Park G, Cho DY, Kim HY, Lee JY, Kim S, Park SB, Shin JH. Comparisons between end-effector and exoskeleton rehabilitation robots regarding upper extremity function among chronic stroke patients with moderate-to-severe upper limb impairment. Sci Reports 2020;10(1):1-8.

[11] Cook A, Hussey S. Assistive Technologies: Principles and Practice. St. Louis, MO: Mosby Year Book Inc.; 2002.

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F, Rijswijk H. (1990). The functional recovery of stroke: a comparison between neuro-developmental

treatment and the Brunnstrom method. Scandinavian Journal of Rehabilitation Medicine 1990;22(1):1–8.

[13] TWI Ltd. What are technology readiness levels (TRL)? UK: Granta Park, Great Abington, Cambridge. Accessed on 17 Feb 2023 from https://www.twi-global.com/technical-knowledge/faqs/technology-readiness-levels.