PT Systems

PT systems LOGO

Overview

Definition

Development

Testing

The Team

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OVERVIEW

PT Systems is a team composed of five mechanical engineering students from the University of Nevada, Reno. The Patient Transfer Device (PTD) was designed to aid in moving a patient between hospital beds and gurneys. The goal of the PTD is to alleviate the risk of injury to the patient as well as the staff when moving a patient. The PTD will achieve this by supporting the weight of the patient and moving them horizontally between surfaces with minimal help from the staff. This results in a safe and reliable platform upon which to transfer a patient.

PT Systems-8-PTD
PTD

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DEFINITION

Need

Medical facilities around the world are using a variety of techniques to move a patient from a bed to a gurney and vice-verse. Most of these techniques are causing back injuries for medical staff, injuries to patients, as well as severe discomfort for patients. Hospitals and other medical facilities need a safer patient transfer process. The Patient Transfer Device (PTD) addresses this need by enabling the use of less nurses and less physical interface between the nurse and the patient. To solve this need the PTD’s specifications are safety, efficiency, and simplifying the method of moving patients.

Design Objectives

Due to the challenges that exist with the patient transfer process, we have set important qualitative design goals for the PTD. These design goals are crucial to meeting the current need for a safe and efficient method of moving patients. Our PTD design operates so that minimal human involvement is required while also reducing work related risk and minimize in-hospital patient injury. Overall, the safety goal can be met reducing labor and insurance costs that many patient care facilities incur. The patient transfer device is also designed to be versatile and mobile. The PTD is easy to store and able to be moved to different locations conveniently. Ultimately, PT Systems Patient Transfer Device is a safer and more efficient method of patient transfer throughout a medical building.

Engineering Specifications

1 Maximum Weight Capacity Maximum weight to be transferred by PTD should not exceed 500 lbs .
2 Total Size Should be approximately 18 inches by 24 inches
3 Maximum Weight of PTD Should weigh no more than 25 lbs
4 Final Cost Final cost of product should not exceed $500.

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DEVELOPMENT

The Patient Transfer Device will be constructed from strong materials, and be able to move patients up to 500 lbs. As part of the efficiency criterion and cost effectiveness of the PTD, the translating board design will be built at a relatively low cost and planned to last for several thousand uses. Compared to what is used currently, our translating board design is more robust than the generic roller board that is being used at Renown Medical Center for transferring patients.

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Current Method of Patient Transfer used at Renown Medical Center

The proof of concept design for the PTD will incorporate durability to prevent structural failure. The translating board design was chosen as our POC because it proved to be a safer design not only due to its construction, but also due to its easy implementation. Most procedures utilized by medical facilities require the personnel to manually lift and move patients from one bed to another. This has proven to cause many injuries among the medical staff and even to the patients. The translating board is designed so that two people will be able to easily implement it to assist in moving a patient without the risk of injury to themselves or the patient. Safety is paramount for our design of the PTD and the translating board design will meet these safety requirements. This PTD design will prove to be efficient, cost effective, and safe.

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Proof of Concept Design for PTD

The final design for the PTD uses a motorized conveyor system to assist in transferring patients between beds. Powered by an 18 volt drill motor, the motorized system lessens nurse involvement during the transfer process, and lowers the difficulty of moving heavier patients. The final design is intended to be symmetrical, which will lower the amount of time needed to transfer a patient. Shown below is the final design concept for the PTD from a bottom view perspectiv. It also shows how we intend to house the motor and apply tension in the belt with tensioners. Some of the conveyor belt was removed so that it shows the roller inside.

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Final Design for PTD

The final prototype will be fabricated using basic, in-house methods and readily available materials. The only specialized skill required for manufacturing is welding. Aside from a welder, fabrication will also require a heat source such as a torch. The only other tools used will be a drill, grinder, sheet metal brake, and sheet metal shear.

The frame is constructed of 1 in. square tubing and 1in x .5in. rectangular tubing. The pieces must be cut to length. In our assembly, a chop saw will be utilized. Once cut, the rectangular end pieces must be drilled to accept threaded inserts. After welding the inserts into place, a slotted hole must be cut into the end pieces of the frame so that the adjusters can move the end roller outward to provide belt tension. There also needs to be relief holes drilled so that when the motor is mounted in its housing, the motor mount screw heads will not interfere with the frame. Next, the frame is welded together taking care to make sure it is symmetric from corner to corner. This concludes the construction of the frame. The next components that needs to be built are the rollers.

The passive rollers are made from aluminum Schedule 40 pipe. After cutting the pipe to length, the ends must be heated with a torch in order to expand them. While the pipe ends are still hot, the bearings are inserted. The steel roller has a slightly larger inside diameter so heating is not necessary. Carefully position the solid axle assembly into one end of the steel roller and weld it in place. Install a bearing in the other end of the steel roller. This concludes the construction of the rollers. The last component that needs to be fabricated is the motor housing.

Using a sheet metal shear the team will cut the pieces for the motor housing. After the pieces are cut to size, the brake is used to put the proper bends into the pieces. Next, the mounting holes for the motor and the housing can be drilled. Then a hole must be drilled so that the output shaft of the motor can mate with the drive roller. Lastly, the pieces of the motor housing are welded together and the welds cleaned up to provide a smooth surface around the perimeter of the housing. Finally, with all the pieces ready, the prototype can be assembled.

Below is the plan drawing and exploded view of the PTD prototype.

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Final Prototype Plan Drawing

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Prototype exploded view

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TESTING

The results of the POC testing were considered successful although they were not definitive. Early estimations by group members suggested that the torque required to move the belt with an added load needed to be less than approximately 30ft-lbs. This number was primarily based on experience and simplified hand calculations with a large error factor added in. A torque wrench was used to apply the force needed to move a load resting on the PTD. Testing began with a load of 200lbs. It was then increased several times until a load of 480lbs was achieved. The test results, although not definitive, provided the group with enough information to begin implementing motors into the future design of the PTD. The frame of the PTD was updated in several ways due to the proof-of-concept. The frame was deemed too wide, too heavy, and the channel used for the ends was difficult to fit threaded inserts into for welding. The channel also made it difficult to implement a belt tensioner, which was desired since there was some belt slippage during testing. To solve these problems, the frame design was first narrowed. During the “simulated use” test the team saw that the lateral distance travelled by the “patient” was excessive. Narrowing the frame solved that. Next, the frame and the rollers were shortened. This was done to save weight. Lastly, the design was updated to include 1 in x .5 in rectangular tubing as the frame ends rather than channel iron. This provides a flat surface for welding the inserts and for an adjustment mechanism to slide on. The changes in the design impacted the materials and the overall cost of the device prototype.


PTD Testing In Action

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MEET THE TEAM

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Sean Neely (Team Leader): Sean is a senior in mechanical engineering at the University of Nevada, Reno. He currently assists research at the University of Nevada, Reno, developing projects such as Autonomous Systems and Tissue Microarray research. He is the president and team leader of PT Systems whose responsibility is closely managing all work related directly to the team project. His experience as a leader outside the company realm has given him the tools needed to lead the PT Systems team successfully.

 

 

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Mark Mandeville: Mark is a senior in mechanical engineering at the University of Nevada, Reno and is set to graduate in the spring of 2014. He has 15 years’ of experience in computer aided design and project management. As Project Designer, Mark has helped the team design the PTD from concept to reality. He also is in responsible for building PT Systems website and technical layout. Inspired the idea of developing the Patient Transfer System after a family member was dropped in a hospital while being moved.

 

 

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A.J. Naveran: Alfonso is a senior mechanical engineering student at the University of Nevada, Reno. He has seven years of hands-on experience as a fabricator and welder. Due to this knowledge, he brings a strong level of hands-on capability to the PT Systems team. As Lead Production Manager, Alfonso is directly responsible for overseeing the fabrication and production of the PTD. His technical abilities are essential for the team in order to create a successful product that will be widely used by the medical industry.

 

 

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Mike Mandeville: Michael is in his final year of mechanical engineering studies at the University of Nevada, Reno. He has several years’ experience in technical analysis and specification. As the Systems Analysis Coordinator, Michael is responsible for the testing and overall technical analysis of the PTD.

 

 

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Catlin Wagner: Catlin is a senior studying mechanical engineering at the University of Nevada, Reno with a minor in renewable energy. He has worked at a gold mine for the last three years, giving him experience in communication and safety. Due to his outside experience, Catlin leads the safety and project communication aspects for PT Systems.


 

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