Transaction Dynamic Ease Allowance in Arm Raising of Functional Garment Roger Ng ＊1,Leung-fu Cheung ＊2 and Winnie Yu ＊1 ＊1 Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Hong Kong ＊2 Department of Mathematics, The Chinese University of Hong Kong, Shatin, Hong Kong Abstract :The functional garments are important protective devicefor the disciplinary forces, such as police, fireman and soldier. Typical protective garments are made of special non-stretchable fabric and hence can restrict the movement of the wearer if the garment is not designed properly. A protective garment that can ensure maximal range-of-motion can be a difference of life and death when the disciplinary force is on duty. There are many aspects of range-of-motion. In the current study, we address the question of the appropriate amount of dynamic ease allowance (movement ease) required for any given height that the arm is supposed to reach.The relationship among the dynamic ease allowance, under arm sleeve length, and side seam length was derived, by using the rod joint model of the human being and assuming the motion is a cross-sectional one along the frontal plane. Sixty subjects wore the special net garment to record the reference of zero dynamic ease allowance, and then the adjustable garments of different scye depth, which is related to the dynamic ease allowance. The subjects were asked to move their arm along a vertical plane, from rest position to the maximum height that they can reach. Such motions were recorded by a motion capturing system. The experimental data was compared to the theoretical prediction. Since the analysis was conducted using the 3-D data and the garment measurements must be converted from the 3-Denvironment (when the garment is worn) to the 2-D environment (when the garment is not worn). The conversionapproximation is also presented. Consequently, when the required posture is known, the required scye depth and the required dynamic seam allowance can be found. The armhole can be designed accordingly. (Received 14 February, 2007, Revised 25 April 2008) 1. Introduction garment surface along the cross-section of the key body landmarks. In the current study, the dynamic ease In garment pattern design, the extra spacing between allowance at the armhole is defined as the difference the garment and the wearer is called the ease allowance. between the scye depth of the arm and the vertical Ease allowances can be classified according to three thickness of the arm at the armhole along the cross- different functions and can be defined in two different sectional plane that is perpendicular to the frontal plane. ways. Firstly, the basic movements, such as breathing and This definition is related to the radial definition, because sitting, require static ease allowance (also known as the difference between the scye depth and the thickness is comfort ease). Secondly, an extreme posture, such as considered in this article as the cross-sectional radial ease raising one’s toe to hit one’s head, needs dynamic ease allowance along the plane of the shoulder joint, allowance (also known as movement ease). Thirdly, the containing the top shoulder point, bottom shoulder point garment itself needs styling ease, which is the extra and the underarm. spacing to conform to the required silhouette. Moreover, In this article, the focus is on the measurement of the two common conventions of defining the ease allowance armhole of a functional garment with dynamic ease include the circumferential definition [1] and the radial allowance by finding out the shape of the garment pattern definition [2, 3]. In the circumferential definition, the that allows the wearer to perform certain given extreme tailors define the ease allowance by the excess girth postures. From the theoretical point of view, both the measurement at the key body landmarks, such as bust, body and the garment are considered as free-formed waist and hip. This definition is the most popular and surfaces, with a planar cross-section at the armhole. widely used in the industry. On the other hand, the The study commenced with a selection of the critical researchers define the radial ease allowance by measuring extreme postures. There were a total of twenty five the radial distance between the body surface and the critical postures selected for study. One of them is the 236 SEN’IGAKKAISHI（報文）Vol.64, No.9(2008) （52） raising of the arm to the highest possible height, which is such as [11, 12, 13, 14, 15, 16]. All of these studies are one of the common movements performed by the experimental in nature. The theoretical formulation of the disciplinary force. Initially, a yoga master was invited to ease allowance with respect to the postures has not been demonstrate these extreme postures and to make reported. recommendation as well as guidelines for the subjects. Then, sixty subjects were invited to repeat these postures 3. Posture definition under a safe condition, meaning that these subjects only tried their best without hurting themselves by over In biomechanics, the set of maximum reachable stretching. Each subject tried the adjustable garments with points of a subject is called the range-of-motion. Such different scye levels, while keeping their personal range-of-motion forms an envelop surface. The complete underarm and sleeve length. The motion was captured by range-of-motion is the union of range-of-motion of each the Vicon™ motion capturing system for data analysis. part of the body. In the case where the body remains in The mathematical model of the dynamic ease allowance, the same place, the body is assumed to be in balance. which is based on the position of shoulder point, under Such complete range-of-motion is defined by a series of side wrist point, side waist point, the side seam length, balanced postures. and the under side sleeve length was derived. The In the extreme posture selection process, the postures theoretical prediction of the scye depth that allows a must achieve the range-of-motion, and/or maximum given height of the under side wrist point arm is stretch of muscles. The postures must also be commonly compared to the experimental results for verification. performed by the disciplinary force, such as firemen, Finally, the discussion is presented. policemen, and soldier during their duty. Then, the postures were classified into three groups : (1) motion of 2. Literature review arm, (2) motion of leg, (3) motion of trunk. These extreme postures can also be classified into 2- The study of the dynamic ease allowance is D postures and 3-D postures. In the 2-D postures, all the equivalent to the study of the fitting problem in motion or movements are restricted on a motion plane, while 3-D kinetic comfort. If a wearer considers the garment fit to be postures are not restricted at all. In this article, the focus is comfortable while doing exercises, there must be on the 2-D posture of maximum arm height to be reached. appropriate amount of spacing between the body and the It is mainly because many of the motion can be garment, which is known as the dynamic ease allowance. partitioned according to the joints of the human subject. The study of dynamic ease allowance can be qualitative Once the origin of the local coordinate system is defined and/or quantitative, such as using statistical analysis. at the joint, the motions of the limbs are reduced to a local Tomita [4] examined the movement ease of the pants, by plane containing the limb. These basic motions are thus measuring the clearance distance between the body the simple cases and they can be combined as the building surface and the pants surface using moiré topography. blocks of the more complicated cases. Makabe [5] reported on the part and amount of ease In the final stage of the posture definition process, a required for upper limb motion. Hirokawa [3] revealed yoga master was invited to try out all the extreme the movement ease on the jacket and concluded the width postures. The yoga master reported the level of stretching across body is an important factor. Prevatt [7] asked the and which muscles were under stretch. The comments subjects to wear selected protective garments to perform a were compiled into a precaution procedure. series of postures and body movements and subjectively Atotalof twenty five postures were selected. A evaluate the comfort level. Larmour [8] studied the best- selected posture showing the restriction of the arm fit garment for senior citizens between the ages of 65 and movement by the sleeve is displayed in Fig. 1, which 74, based on the body measurements. Similarly, Burke [9] shows how the garment can restrict the range-of-motion developed four different prototypes of fit-modified of a subject. Apparently, the armhole is too big. So when garment for ambulatory women between 68 and 94 years the wearer raises her arm, the sleeve is under stretch. The of age to identify the best-fit prototypes. Cho [10] crease lines indicate the direction of the stretch. The designed and studied the mobility of the hospital gowns. figure illustrates a very important difference between the The qualitative analysis was based on the interviews and static ease allowance and the dynamic ease allowance. survey of the female nurses. Furthermore, range-of- For static ease allowance, more space implies less motion and fit is evaluated subjectively and statistically, restriction on the movement, while the dynamic ease （53） SEN’IGAKKAISHI（報文）Vol.64, No.9(2008) 237 Fig. 4 Positioning of light reflecting balls. Fig. 1 Raising of arm.