The Titan Arm

An ASTM Project Grant Helps Enable Biomechatronic Research

As biomechatronic technology has matured over the past 50 years, exoskeletons have emerged as leading tools for augmenting able-bodied performance, assisting human mobility and restoring lost limb function. These systems are anthropomorphic, structural devices that work in conjunction with the body’s natural architecture to aid limb mobility. Exploiting biomimetic design, such devices may be worn in close proximity to the body and transmit torques via powered revolute joints and structural limbs. Controllable, wireless exoskeletons offer significant potential in restoring lost limb function, and enhancing mobility and strength of the user.

The Titan Arm device.

In order to make this sophisticated technology accessible to a large population of users, our team designed and created a proof-of-concept upper body exoskeleton for applications in physical therapy and mobility assistance at extremely low cost. Working as a small senior design team in the mechanical engineering and applied mechanics department of the School of Engineering and Applied Sciences at the University of Pennsylvania, we researched, designed and manufactured a powered upper body known as the Titan Arm over the course of eight months.

The Titan Arm team includes (from left): Elizabeth Beattie, Nikolay Vladimirov, Nicholas McGill and Nick Parrotta.

Funding was immediately necessary because our project was ambitious, and would require investment despite our low cost requirement. One of our most precious funding sources came in the form of an ASTM International project grant. The project grant program required us to submit an in-depth project description, which helped us to better outline and plan Titan. Our proposal resulted in a $500 grant from ASTM, which was used to acquire materials and components and cover miscellaneous costs throughout the year. Without the grant, we would not have been able to integrate as many features or abilities into the suit.

In addition to securing funding, we worked hard to understand our applications and use cases. By talking to physical therapists at the Hospital of the University of Pennsylvania, as well as potential users undergoing physical therapy, we were able to identify the most important needs, which were strength, range of motion and cost. This dictated the required functionality of our suit and guided our design decisions throughout the project.

Robust mechanical design, novel actuation methods and embedded systems were integrated to create the Titan Arm. Our solution employs a controllable limb with a powered elbow joint coupled with three unpowered rotational joints at the shoulder. As a prototype exoskeletal system, our device has met numerous performance metrics, including a low inertia arm, actuation non-local to the joint, wireless power and operation, back-driveability and low cost development. Titan Arm offers a solution that may be extended to accessible exoskeletal systems for use in assisting human mobility and regaining limb function, allowing disabled populations such as the elderly to regain independence and mobility.

As we worked to develop Titan, it became apparent that we would need to utilize a variety of techniques from a multitude of fields including mechanical, electrical and system design as well as additive, subtractive, composite and circuit manufacturing. To integrate such eclectic fields into a working proof-of-concept, we needed ways to better understand and work with different materials, techniques and concepts. ASTM International standards offered a way to more easily quantify and discuss diverse, cross-disciplinary topics among ourselves and with professionals in industry. Without well-defined test procedures and terminology, it would have been much harder to design and create Titan. (See Table 1 — ASTM Standards Consulted for Titan Project.)

Table 1 — ASTM Standards Consulted for the Titan Arm Project.

Topic

ASTM Standards

Additive Manufacturing

  • F2792, Terminology for Additive Manufacturing
  • F2921, Terminology for Additive Manufacturing — Coordinate Systems and and Test Methodologies

Electrical and Circuit Design

  • D5470, Test Method for Thermal Transmission Properties of Thermally Conductive Electrical Insulation Materials
  • D1711, Terminology Relating to Electrical Insulation
  • D3636, Practice for Sampling and Judging Quality of Solid Electrical Insulating Materials

Composite Materials Use

  • D3039/D3039M, Test Method for Tensile Properties of Polymer Matrix Composite Materials
  • D7264/D7264M, Test Method for Flexural Properties of Polymer Matrix Composite Materials

As a project, Titan has hit all of its performance metrics, and has the potential to improve many lives. The suit is capable of augmenting user strength by up to 40 lbs (18 kg), enabling users to repeatedly lift objects without fatigue. In a manufacturing setting, this would improve worker throughput and utilization while simultaneously reducing injury rates. This force can also be applied resistively, allowing users to build muscle and regain their strength. The suit continually measures range of motion and force data, which it then transmits to doctors. This information can be used to remotely track improvement and create custom physical therapy routines for each patient. The suit is tetherless and weighs just 18 lbs (8 kg), making it easy to wear and portable — two of the most important criteria to enable adoption. Additionally, the suit is adjustable to accommodate a wide range of users.

Nikolay Vladimirov tests the Titan Arm with repetitive lifting at the device’s maximum working load of 40 lbs (18 kg).

Titan is most powerful as a tool to empower its users and grant them independence. For occupational lifters, this is the ability to work without fear of fatigue-based injuries. For physical therapy patients, this allows at-home, customized regimens that speed recovery and reduce the overall interruption to their daily lives. And for the permanently injured, such a suit could provide the strength and dexterity necessary to perform everyday tasks unassisted. With further development, we hope that Titan will be able to enrich the lives of millions.

Titan Arm was designed and manufactured by teammates Elizabeth Beattie, Nicholas McGill, Nick Parrotta and Nikolay Vladimirov as seniors at the University of Pennsylvania. Beattie majored in mechanical engineering, and is currently pursuing her Ph.D. McGill double-majored in electrical and mechanical engineering, and is pursuing his MSE in robotics. Parrotta majored — and is now pursuing an MSE — in mechanical engineering. Vladimirov, a mechanical engineering major, now works at IDEO, a global design consultancy.

This article appears in the issue of Standardization News.