THE INFLUENCE OF THE INTERFACE PEAK PRESSURE OF THE DYNAMIC SEAT CUSHION, ACTUATED BY PNEUMATIC MUSCLES, ON THE SKIN

THE INFLUENCE OF THE INTERFACE PEAK PRESSURE OF THE DYNAMIC SEAT CUSHION, ACTUATED BY PNEUMATIC MUSCLES, ON THE SKIN Andreea Iancu *, Viviana Filip ** * Valahia University of Targoviste, Doctoral Studies, ** Valahia University of Targoviste, Multidisciplinary Research Institute for Science and Technologies, Strada Unirii, nr. 18, Targoviste, Romania iancu_andreea85@yahoo.co.uk, viviana.filip@icstm.ro Abstract - The main objective of this paper is to determine the value of interface, recorded at the contact between the user and the dynamic seat cushion, actuated by pneumatic muscles. The pneumatic device will be loaded with weights started from 10 kg to 70 kg at 3 bar air supply and also for 4 bar air supply. The interface it will be determined by mathematical calculation for each weight. By getting these values, we could do a comparative analysis of experimental data obtained from measurements with data obtained by researchers in the field. The main advantage of using dynamic seat cushion actuated by pneumatic muscles will emerge from the minimum interface peak. At the end, we presented the main conclusion of the experimental research, and the opinion of the specialist in this field, who had used the device. Keywords: Seat cushion, pneumatic muscle, interface, interface peak. 1. Introduction The interface is defined as the distributed between the seat and the supporting surface when the user is seated. This feature has been analyzed by researchers in order to evaluate the user behavior when seated position and substrate properties. Blood increases physiological exercise, strong emotional states in sleep and dreams differ from sex to sex, age and the elderly. It falls during quiet sleep. Pathological increase in cases of fever or hypertension. The normal values are 100-130 mmhg for men and 90-120 mmhg for women [1]. Pressure measurements recorded between the user interface and the base began through the health system [2]. Hobson researcher analyzed the interface for wheelchair user. According to his studies, concluded that the interface recorded minimum value when the seat was tilted back and his feet were flat on the floor. had another distribution. The interface peaks recorded when the novel subject was seated on a surface feet high. Sliding and bending causes a maximum interface [3]. Placing the seating position is a body position where body weight is transmitted to the substrate through the ischial tuberosity (bones of settlement) of the pelvis and soft tissues surrounding them. According to studies, it is estimated that about a quarter of the working areas of industrial countries is sedentary [4]. measurements recorded in a sitting position were made in different industries where comfort is an important issue settlement [5] because it is considered that positively affects employee productivity comfortable seats, while the seats uncomfortable medical conditions worsen pre-existing conditions such as back pain. Kosiak researcher measured the on the pelvic tissues from 11 adults who were placed on different types of surfaces. The seats have two types of areas: an area of a surface foam and supply air alternately. According to survey results, it was found that alternative mattress has the ability to minimize the on the ischial interface similar values capillary - 32 mmhg - 4.3 kpa [6]. Lindane, Greenway and Piazza [7] were the first who developed a measuring device interface. The central idea of this study was to develop a measurement system for human full body when supported by a mattress. The study concluded that is exerted on the skin may be influenced by the resistance of the measuring device. The different forms of body influenced different values of interface. Researcher Bush [8] was the first to measure interface using electronic sensors in ischial tuberosities area.. Subsequently, this was followed by researchers H.T.E. Hertzberg, L.K. Hollay., Long S., Drummond D.S., Fisher W, et al. [9], [10], [11], [12]. 2. Current state of research on determining the interface Researchers Maurizio Ferrain, Giussepe Andreoni, Antonio Pedotti, have conducted research to assess four types of wheelchair cushions. The Romanian Review Precision Mechanics, Optics & Mechatronics, 2013, No. 44 125

The study had as main objective to determine the maximum interface peak registered between the user and the device. The four types of pillows analyzed are: rooms with pillow foam, polyurethane gel pillow, air pillow, cushion foam and silicone gel in the polyurethane [13]. Figure 1 : Seat cushions for wheelchair 1- rooms with pillow foam, 2 - polyurethane gel pillow, 3 - air pillow, 4 - cushion foam and silicone gel in the polyurethane According the research, the values of the interface peak recorded for the analyzed seat cushions, are in the following table: Table 1 Values for interface for the analized seat cushions No. Seat cushion peak 1 Cushion 1 - rooms with pillow foam 101 mmhg 2 Cuschion 2 - polyurethane gel pillow 112 mmhg 3 Cushion 3 - air pillow 93 mmhg 4 Cushion 4 - cushion foam and silicone gel in the polyurethane 71 mmhg As this research shows that air cushion has minimum values of on a small area compared to other pillows analyzed. This disadvantage is a lack of anatomical design, that matches the shape of the seat [13]. The lack of correlation between the air supply of the room and height of rooms, according to researchers Maurizio Ferrain, Giussepe Andreoni, Antonio Pedotti, is a disadvantage for the minimum value of interface [13]. Researchers Jan T.M. Weststrate, Hajo A. Bruining, Richard H.M. Goossens, Freerk Heule, Wine C.J. Hop, have analyzed the repeatability of measurements of interface in people who have a high risk of sore development machines [14].The interface was measured by means of sensors. It was considered two sets of measurements, both right thigh and to the left [14]. According to surveys, the following values were the points of interface : Table 2 Values of interface peak for the right thigh and for the left Left thigh Value of interface peak 1 First measurement 2 Second measurement Right thigh Value of interface peak 45,00 mmhg 1 First measurement 40,5 mmhg 42 mmhg 2 Second measurement 36,75 mmhg Since the body has a flat shape, the interface will vary depending on where it is measured. The interface will always be large amounts protruding areas of the body, because they contain strong bone structure beneath the skin, such as the scapula, sacrum, hips, heel against the flat areas of the 126 The Romanian Review Precision Mechanics, Optics & Mechatronics, 2013, No. 44

body where the interface will be the minimum value. Body shape can be changed when it is in a period of severe disease [15], or when it is in the same position for a long period of time [16]. Allen Siekman researcher at the Centre The Comfort Company conducted a comparative analysis of interface points for different types of wheelchair cushions. Were analyzed five areas: left and right trochanter, left and right ischial tuberosity and sacrum [17]. Using an advanced interface measurement was obtained following matrix form: Figure 2: in points using measuring system RIT right ischial tuberosity; LIT - left ischial tuberosity; RTroch - right trochanter; LTroch - left trochanter 3. Calculation of the to the pneumatic interface between the user and the device, the supply of 3 bar and 4 bar To demonstrate the use of dynamic device driven by pneumatic muscles pillow type does not lead to increased sores by progressive degradation of skin integrity, based on experimental data obtained by mathematical calculation will determine the interface value recorded between user and device. The user is treated with a weight which was placed on the dynamic device as follows: 10 kg, 20 kg, 30 kg, 40 kg, 50 kg, 60 kg, 70 kg. The calculation of the interface is determined routes is performed from the power of 3 bar and 4 bar. In determining the interface values are considered races by pneumatic muscles when they are charged with weights that you are free weights. We considered in the experimental research, five for each weight in order to track the behavior of elastic pneumatic muscles and how this behavior influences the values of the points interface, and user comfort level. 4. Experimental Results. Conclusions The results are presented in tabular form, in order to experience a degree of repeatability of the value of racing by pneumatic muscles during refueling device of 3 bar and 4 bar. According to data contained in the tables below, taking into account the degree of repeatability of the value of racing is low, due to elastic behavior of the pneumatic muscles. No. Table 3 Values for interface for 10 kg, at air supply of 3 bar Measurement Weight 10 kg peak Weight 10 kg peak 1 Cycle 1 117,187 0,0178 104,748 0,0145 2 Cycle 2 113,63 0,0170 106,534 0,0150 3 Cycle 3 115,74 0,0178 108,695 0,0156 4 Cycle 4 117,924 0,0184 110,29 0,0158 5 Cycle 5 118,67 0,0187 108,506 0,01566 The Romanian Review Precision Mechanics, Optics & Mechatronics, 2013, No. 44 127

- loading with weight of 10 kg, at air supply of 3 bar - unloading with weight of 10 kg, at air supply of 3 bar According to the data in Table 3, we can see that the interface values recorded when the seat cushion is loaded with weight of 10 kg, are higher than those obtained when the device is unload with the same value, for 3 bar. No. Table 4 Values for interface for 10 kg, at air supply of 4 bar Measurement Weight 10 kg Weight 10 kg peak peak 1 Cycle 1 144,899 0,027 128,839 0,02212 2 Cycle 2 146,141 0,0284 125,20 0,2088 3 Cycle 3 144,397 0,0277 127,594 0,02169 4 Cycle 4 146,828 0,028724 126,135 0,0212 5 Cycle 5 144,899 0,027 122,87 0,02011 - loading with weight of 10 kg, at air supply of 4 bar - unloading with weight of 10 kg, at air supply of 4 bar According to the data in Table 4, we can see that the interface values recorded when the seat cushion is loaded with weight of 10 kg, are higher than those obtained when the device is unload with the same value, for 4 bar. Figure 3: peak for loading the device with 10 kg, at air supply of 3 bar and 4 bar Figure 4: peak for unloading the device with 10 kg, at air supply of 3 bar and 4 bar Table 5 Values for interface for 20 kg, at air supply of 3 bar Weight 20 kg peak Weight 20 kg peak 1 Cycle 1 208,33 0,028 216,138 0,0311 2 Cycle 2 208,33 0,028 200,749 0,0267 3 Cycle 3 206,611 0,0283 201,612 0,0270 4 Cycle 4 206,611 0,02832 202,702 0,0272 5 Cycle 5 206,611 0,02832 207,296 0,0286 - loading with weight of 20 kg, at air supply of 3 bar - unloading with weight of 20 kg, at air supply of 3 bar According to the data in Table 5, we can see that the interface values recorded when the seat cushion is loaded with weight of 20 kg, are higher than those obtained when the device is unload with the same value, for 3 bar. 128 The Romanian Review Precision Mechanics, Optics & Mechatronics, 2013, No. 44

Table 6 Values for interface for 20 kg, at air supply of 4 bar Weight 20 kg peak Weight 20 kg peak 1 Cycle 1 248,199 0,0410 227,27 0,03441 2 Cycle 2 254,237 0,0429 232,414 0,0359 3 Cycle 3 256,41 0,0438 225,591 0,0339 4 Cycle 4 259,515 0,0446 228,658 0,0347 5 Cycle 5 252,44 0,0424 215,703 0,0310 - loading with weight of 20 kg, at air supply of 4 bar - unloading with weight of 20 kg, at air supply of 4 bar According to the data in Table 6, we can see that the interface values recorded when the seat cushion is loaded with weight of 20 kg, are higher than those obtained when the device is unload with the same value, for 4 bar. Figure 5: peak for loading the device with 20 kg, at air supply of 3 bar and 4 bar Figure 6: peak for unloading the device with 20 kg, at air supply of 3 bar and 4 bar Table 7 Values for interface for 30 kg, at air supply of 3 bar Weight 30 kg Weight 30 kg peak peak 1 Cycle 1 267,86 0,032 267,85 0,0317 2 Cycle 2 272,595 0,03301 275,195 0,03365 3 Cycle 3 275,061 0,03359 270,692 0,0325 4 Cycle 4 275,938 0,0338 269,138 0,0321 5 Cycle 5 275,938 0,0338 365,33 0,03126 - loading with weight of 30 kg, at air supply of 3 bar - unloading with weight of 30 kg, at air supply of 3 bar According to the data in Table 7, we can see that the interface values recorded when the seat cushion is loaded with weight of 30 kg, are higher than those obtained when the device is unload with the same value, for 3 bar. Table 8 Values for interface for 30 kg, at air supply of 4 bar Weight 30 kg Weight 30 kg peak peak 1 Cycle 1 320,512 0,0456 313,632 0,0437 2 Cycle 2 313,975 0,0437 318,877 0,0451 3 Cycle 3 312,49 0,0433 323,368 0,0464 4 Cycle 4 311,72 0,0431 316,99 0,0446 5 Cycle 5 315,214 0,0441 312,847 0,04399 - loading with weight of 30 kg, at air supply of 4 bar - unloading with weight of 30 kg, at air supply of 4 bar The Romanian Review Precision Mechanics, Optics & Mechatronics, 2013, No. 44 129

According to the data in Table 8, we can see that the interface values recorded when the seat cushion is loaded with weight of 30 kg, are higher than those obtained when the device is unload with the same value, for 4 bar. Figure 7: peak for loading the device with 30 kg, at air supply of 3 bar and 4 bar Figure 8: peak for unloading the device with 30 kg, at air supply of 3 bar and 4 bar Table 9 Values for interface for 40 kg, at air supply of 3 bar No. Measurement Weight 40 kg peak Weight 40 kg peak 1 Cycle 1 384,62 0,046 367,917 0,0451 2 Cycle 2 369,458 0,04537 366,748 0,0447 3 Cycle 3 369,458 0,04537 358,85 0,0428 4 Cycle 4 369,458 0,04537 367,647 0,045 5 Cycle 5 373,692 0,04565 373,2271 0,0464 - loading with weight of 40 kg, at air supply of 3 bar - unloading with weight of 40 kg, at air supply of 3 bar According to the data in Table 9, we can see that the interface values recorded when the seat cushion is loaded with weight of 40 kg, are higher than those obtained when the device is unload with the same value, for 3 bar. Table 10 Values for interface for 40 kg, at air supply of 4 bar No. Measurement Weight 40 kg peak Weight 40 kg peak 1 Cycle 1 402,144 0,0538 417,827 0,0581 2 Cycle 2 402,900 0,0541 418,184 0,05827 3 Cycle 3 401,069 0,0535 420,07 0,0588 4 Cycle 4 405,405 0,0547 434,279 0,0628 5 Cycle 5 403,225 0,0541 424,436 0,0600 - loading with weight of 40 kg, at air supply of 4 bar - unloading with weight of 40 kg, at air supply of 4 bar According to the data in Table 10, we can see that the interface values recorded when the seat cushion is loaded with weight of 40 kg, are lower than those obtained when the device is unload with the same value, for 4 bar. 130 The Romanian Review Precision Mechanics, Optics & Mechatronics, 2013, No. 44

Figure 9: peak for loading the device with 40 kg, at air supply of 3 bar and 4 bar Figure 10: peak for unloading the device with 40 kg, at air supply of 3 bar and 4 bar Table 11 Values for interface for 50 kg, at air supply of 3 bar Weight 50 kg peak Weight 50 kg peak 1 Cycle 1 487,013 0,063 489,811 0,0639 2 Cycle 2 494,722 0,0651 496,031 0,0653 3 Cycle 3 502,68 0,0673 499,600 0,0665 4 Cycle 4 503,2206 0,0675 502,68 0,0672 5 Cycle 5 505,6634 0,0681 506,756 0,0684 - loading with weight of 50 kg, at air supply of 3 bar - unloading with weight of 50 kg, at air supply of 3 bar According to the data in Table 11, we can see that the interface values recorded when the seat cushion is loaded with weight of 50 kg, are higher than those obtained when the device is unload with the same value, for 3 bar. Table 12 Values for interface for 50 kg, at air supply of 4 bar Weight 50 kg peak Weight 50 kg peak 1 Cycle 1 566,46 0,0855 573,39 0,0874 2 Cycle 2 571,646 0,0869 576,923 0,0885 3 Cycle 3 590,551 0,0929 591,85 0,0933 4 Cycle 4 602,119 0,0966 575,153 0,0879 5 Cycle 5 568,18 0,0860 597,13 0,0949 - loading with weight of 50 kg, at air supply of 4 bar - unloading with weight of 50 kg, at air supply of 4 bar According to the data in Table 12, we can see that the interface values recorded when the seat cushion is loaded with weight of 50 kg, are lower than those obtained when the device is unload with the same value, for 4 bar. Figure 11: peak for loading the device with 50 kg, at air supply of 3 bar and 4 bar Figure 12: peak for unloading the device with 50 kg, at air supply of 3 bar and 4 bar The Romanian Review Precision Mechanics, Optics & Mechatronics, 2013, No. 44 131

Table 13 Values for interface for 60 kg, at air supply of 3 bar Weight 60 kg peak Weight 60 kg peak 1 Cycle 1 681,82 0,10 661,764 0,19 2 Cycle 2 692,307 0,1064 652,1739 0,094 3 Cycle 3 698,757 0,1082 654,069 0,0948 4 Cycle 4 697,67 0,1083 657,89 0,0961 5 Cycle 5 698,75 0,1083 659,824 0,0965 - loading with weight of 60 kg, at air supply of 3 bar - unloading with weight of 60 kg, at air supply of 3 bar According to the data in Table 13, we can see that the interface values recorded when the seat cushion is loaded with weight of 60 kg, are higher than those obtained when the device is unload with the same value, for 3 bar. No. Table 14 Values for interface for 60 kg, at air supply of 4 bar Weight 60 kg Weight 60 kg peak Measurement peak 1 Cycle 1 907,28 0,1821 914,63 0,1857 2 Cycle 2 922,13 0,188 934,38 0,1939 3 Cycle 3 953,389 0,2016 961,538 0,204 4 Cycle 4 909,09 0,1835 953,389 0,2016 5 Cycle 5 933,609 0,1933 945,37 0,198 - loading with weight of 60 kg, at air supply of 4 bar - unloading with weight of 60 kg, at air supply of 4 bar According to the data in Table 14, we can see that the interface values recorded when the seat cushion is loaded with weight of 60 kg, are lower than those obtained when the device is unload with the same value, for 4 bar. Figure 13: peak for loading the device with 60 kg, at air supply of 3 bar and 4 bar Figure 14: peak for unloading the device with 60 kg, at air supply of 3 bar and 4 bar Table 15 Values for interface for 70 kg, at air supply of 3 bar Weight 70 kg - loading with weight of 70 kg, at air supply of 3 bar peak 1 Cycle 1 795,45 0,12 2 Cycle 2 815,21 0,1264 3 Cycle 3 810,185 0,124 4 Cycle 4 808,936 0,1246 5 Cycle 5 815,21 0,1246 132 The Romanian Review Precision Mechanics, Optics & Mechatronics, 2013, No. 44

Table 16 Values for interface for 70 kg, at air supply of 4 bar Weight 70 kg peak 1 Cycle 1 1299,5 0,321 2 Cycle 2 1293,65 0,308 3 Cycle 3 1370,192 0,328 4 Cycle 4 1270,57 0,3073 5 Cycle 5 1323,084 0,330 - loading with weight of 70 kg, at air supply of 4 bar Figure 15: peak for loading the device with 70 kg, at air supply of 3 bar and 4 bar The device was tested in Valleriana Rehab Centre by the recovery experts doctors and home care to observe the impact on the skin. Dr. Lucian Chetan specialist in emergency medicine and Dr. Dumitrescu Dana, specialist in rehabilitation, concluded from use device that performs a massage on the skin, is indicated for the recovery of persons who have suffered various types of accidents for elderly are in wheelchairs, partially or totally immobilized. According to Ms. Mihaela Stanciu, "Residential Centre medico-social assistance for the elderly, the only center of its kind in South Muntenia, the device can be attached to the back massage, but it can be integrated under the people who are bedridden for achieving a massage to eliminate the state of annoyance. Acknowledgements This work was supported by the Operational Programme for Human Resources Development 2007-2013. Priority Axis 1 "Education and training in support of economical growth and social development based on knowledge". Major area of intervention 1.5. "Doctoral and postdoctoral programs in support of research". Project title: "Doctoral preparing of excellence for the knowledge society PREDEX". POSDRU/CPP 107/DMI1.5/s/77497. 4. Conclusions In Figures 3 to 15, are the values of the interface peak at air supply points 3 bar and 4 bar, so when added weight from 10 kg to 70 kg and when the weights are removed from 70 kg to in the 10 kg. According to the data in the table above, the feed device constant of 3 bar following: - recorded when the devices are standard weights higher values compared with in which weights are removed. - Differences between the s of the order hundredths - Hysteresis does not have a linear trend, easy to follow due to elastic behavior of pneumatic muscle - The interface peak has minimal value, compared with the results obtained by researchers in various studies. According to the data in the table above, the feed device constant of 4 bar the following: - recorded when the devices are standard weights lower values compared with in which weights are removed. - Differences between the s of the order hundredth - Hysteresis has a linear trend, easy to follow due to elastic behavior of pneumatic muscle - The interface has minimal value in points, compared with the results obtained by researchers in various studies. For all the results, we concluded that the values for the interface peak, for each weight, and supply, do not influence the skin integrity, and the device is able to support different weight. 5. References: [1] Wikipedia. (2013, Mai) Wikipedia. [Online]. http://ro.wikipedia.org/wiki/presiune_sanguină [2] Porter J.M., Robertson N.K.B. Gyi D.E., "Seat measurement technologies:considerations for The Romanian Review Precision Mechanics, Optics & Mechatronics, 2013, No. 44 133

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