Human-interactive control of a hydraulically actuated patient transfer assist device with redundant obstacle sensing

2016 ◽  
Author(s):  
Heather C. Humphreys ◽  
Wayne J. Book
Keyword(s):  
Patient Transfer ◽  
Assist Device ◽  
Interactive Control ◽  
Hydraulically Actuated

Caretaker-Machine Collaborative Manipulation With an Advanced Hydraulically Actuated Patient Transfer Assist Device

2014 ◽  
Author(s):  
Heather C. Humphreys ◽  
Wayne J. Book ◽  
James D. Huggins ◽  
Brittney Jimerson
Keyword(s):  
Needs Assessment ◽  
Interface Design ◽  
Spinal Cord Injuries ◽  
Impedance Control ◽  
Neuromuscular Disorders ◽  
Patient Transfer ◽  
Assist Device ◽  
Unique Challenge ◽  
Control Approach ◽  
Hydraulically Actuated

A significant market need has been identified for an improved assist device for transferring mobility limited patients, particularly those who are heavier or bariatric. This paper discusses our needs assessment for a new patient transfer assist device (PTAD), an initial design for a multiple degree of freedom hydraulically actuated device, and possible solutions for the caretaker interface design. The relevant patient population includes those with spinal cord injuries, neuromuscular disorders, and the elderly; most patients are wheelchair users and unable to perform independent transfers. The caretaker interface design for the PTAD presents a unique challenge in terms of human-machine collaborative manipulation, as well as control of a powerful and intrinsically stiff machine in a delicate environment with both the caretaker and patient in the workspace. This paper presents a needs assessment to determine the specific problems with the antiquated current market patient lifts, as well as user input on proposed improvements. It also presents the design of a functional first prototype PTAD, a mechanical simulation, preliminary simulation results on an impedance control approach, and next steps toward design and implementation of a caretaker- and patient-friendly operator interface and control system.

Advanced patient transfer assist device

2018 ◽  
Author(s):  
Heather Humphreys ◽  
Wayne J. Book ◽  
Grace Deetjen
Keyword(s):  
Patient Transfer ◽  
Assist Device

Advanced Hydraulically Actuated Patient Transfer Assist Device

2014 ◽  
Author(s):  
Heather C. Humphreys ◽  
Wayne J. Book
Keyword(s):  
Degrees Of Freedom ◽  
Force Feedback ◽  
Mental Workload ◽  
Static Friction ◽  
Contact Forces ◽  
Degree Of Freedom ◽  
Patient Transfer ◽  
Level Control ◽  
Hydraulically Actuated ◽  
Transfer Device

A new, advanced patient transfer device is being developed for moving mobility limited patients, for example, from a wheelchair to a bed or a floor into a chair. Current market patient lift devices are antiquated and insufficient for customer needs, with only one actuated degree of freedom. The high power to size ratio of hydraulic actuation makes it suitable for moving larger, heavier patients. We have developed a prototype pump-controlled hydraulically actuated patient transfer device that is more maneuverable and agile, using multiple actuated degrees of freedom. We are also working toward developing a more intuitive and safe caretaker interface and control strategy. We have performed an extensive needs assessment; these are a few associated key design requirements relevant to this presented work. A compact package is needed for ease of maneuvering the patient around obstacles in an uncertain environment. The device is capable of producing large forces, so it is desirable for the controller to minimize any unintentional large external contact forces, or provide force feedback. In this system, the caretaker and device work together to maneuver a complex payload, a human body; the operator’s mental workload must be minimized. With humans in the device workspace, safety and stability are necessary, including environment interactions. This new application presents several challenges related to the hydraulic control. First, we are using a separate bidirectional fixed displacement pump with a reversible brushed DC motor for each degree of freedom. The low level control involves obtaining desirable response from each motor-pump-actuator system, while compensating for significant static friction. At a higher level, we are testing several approaches to attain the desired intuitive control and desired dynamics, and minimize the operator workload. First, we are developing a coordinated control using a force input, such that the operator simply pushes on the device in the desired direction of motion. We are testing several different controllers to attain the desired dynamics. This paper presents the design of the machine, the proposed control structures as applied to this application, operator interface options, some preliminary results, and future work.

Hydraulically Actuated Patient Transfer Device With Passivity Based Control

2013 ◽  
Author(s):  
Heather C. Humphreys ◽  
Wayne J. Book ◽  
James D. Huggins
Keyword(s):  
Needs Assessment ◽  
Control Strategy ◽  
Force Sensor ◽  
Patient Transfer ◽  
Hydraulically Actuated ◽  
Passivity Based Control ◽  
Transfer Device

This paper describes the development of a hydraulically actuated patient transfer device, utilizing a force amplifying passivity based control strategy. The patient transfer device is intended for moving mobility limited patients, for example, from a bed to a chair, from a wheelchair into a car, or from the floor into a wheelchair. Our needs assessment has indicated that a more powerful, more easily maneuverable device is needed which is operable by a single caregiver with one hand. For this purpose, we are proposing a coordinated force amplifying control strategy. The caregiver input to the device is measured from a force sensor mounted on the device near the patient. The output is the force applied by the device actuators in the same direction as the input; this force may be amplified to assist the caregiver. Passivity-based control provides a way to implement this force amplifying control to aid in stability, which is critical for a device that interacts directly with humans. This paper describes the implementation of this force amplifying passivity-based control on a simpler pre-prototype two DOF patient transfer device.

Advanced patient transfer assist device with intuitive interaction control

2017 ◽  
pp. 1-11 ◽  
Author(s):  
Heather C Humphreys ◽  
Young Mi Choi ◽  
Wayne J. Book
Keyword(s):  
Patient Transfer ◽  
Assist Device ◽  
Interaction Control

Ultrastructural observations of the aorta of calves implanted with a mechanical left ventricular assist device

1990 ◽  
Vol 48 (3) ◽  
pp. 834-835
Author(s):  
J P Cassella ◽  
V Salih ◽  
T R Graham
Keyword(s):  
Left Ventricular Assist Device ◽  
Ventricular Assist Device ◽  
Left Ventricular ◽  
Aortic Tissue ◽  
Assist Device ◽  
Ventricular Assist ◽  
Transmission Electron ◽  
Left Ventricular Assist ◽  
Preliminary Study

Left ventricular assist systems are being developed for eventual long term or permanent implantation as an alternative to heart transplantation in patients unsuitable for or denied the transplant option. Evaluation of the effects of these devices upon normal physiology is required. A preliminary study was conducted to evaluate the morphology of aortic tissue from calves implanted with a pneumatic Left Ventricular Assist device-LVAD. Two 3 month old heifer calves (calf 1 and calf 2) were electively explanted after 128 days and 47 days respectively. Descending thoracic aortic tissue from both animals was removed immediately post mortem and placed into karnovsky’s fixative. The tissue was subsequently processed for transmission electron microscopy (TEM). Some aortic tissue was fixed in neutral buffered formalin and processed for routine light microscopy.

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