J. Cent. South Univ. (2014) 21: 4142−4149 DOI: 10.1007/s11771-014-2409-2 Robowler: Design and development of a cricket bowling machine ensuring ball seam position RAZA Ali 1 , DIEGEL Olaf 2 , ARIF Khalid Mahmood 2 1. Mechatronics and Control Engineering, University of Engineering & Technology, Lahore 54890, Pakistan; 2. School of Engineering and Advanced Technology, Massey University, Auckland 0632, New Zealand © Central South University Press and Springer-Verlag Berlin Heidelberg 2014 Abstract: The art of cricket bowling is complex and arduous owing to the run-up and ball release time energy requirement to achieve speed and variations. Therefore, human bowlers cannot bowl for extended periods and numerous mechanical bowling machines have been built to help batsmen improve their skills during practice sessions. However, most of these existing machines are designed for spherical balls ignoring the distinguishing physical feature of a cricket ball: the raised equatorial seam, which makes it less of a sphere. The bowlers are known to often benefit from this seam in their pursuit to taking the batsmen’s wicket by imparting swing, spin and bounce variations along-with other bowling variables. This lack of the seam consideration creates a void between human and mechanical bowling. In this work, we present design and development of an automatic bowling machine termed as ROBOWLER to make mechanical bowling more realistic. This machine ensures ball seam position as well as fulfills other constraints. Ball pitching and seam position accuracy results underscore the suitability of this design to enhance the capabilities of mechanical bowling. Key words: robowler; bowling machine; cricket bowling; ball seam; bowling variables 1 Introduction Cricket bowling is a complex and demanding task in which a bowler needs to run and throw the ball accurately to prevent runs being scored whilst inducing errors in the batsman. This dynamic skill of bowling can be thought of a medley of four distinct steps: run-up, leap, delivery stride and follow-through [1]. Figure 1 shows right and left handed bowling actions by two of the world’s renowned fast bowlers of all time [2]. In the run-up step, a bowler approaches the near end of the 20.1 m (22 yards) pitch with batsman facing at the far end, waiting for the ball to be thrown. The bowler in his leap step jumps in the air, arches his back, and lifts his arms in order to get into the delivery stride. In the third step, delivery stride, the bowler moves his left/right arm downwards, rotates his right/left arm holding the ball and throws when it reaches its highest point during the rotation. Then, comes the follow-through in which the bowler eventually stops [3]. Bowling styles vary from bowler to bowler, yet the intention remains to get the batsman declared out by inducing variations in bowling. A cricket ball is not a perfect sphere, i.e., the stitching on the seam is raised and bowlers can utilize this irregularity to create sideways movement by pitching the ball on the seam. Typically, these balls are made from a core of cork, which is layered with tightly wound string, and covered by a leather skin comprising four quarters stitched together to form a major seam in an equatorial plane. Moreover, the quarter seams on both halves of the ball are internally stitched and juxtaposed by 90°. The major seam consists of six rows of stitches with approximately 60 to 80 stretches in each row. With a mass of 156−163 g and approximate diameter of 70 mm a cricket ball is much heavier than a tennis ball [4]. By holding the seam in different ways, it is possible to experiment with the movement off the pitch. Bowling utilizing ball seam is called seam bowling in the cricket community and the stock delivery for the seam bowler is one with the seam upright and the ball moving around its horizontal axis to ensure the seam faces the batsman vertically at all times. On the basis of variations in ball speed at release and the spin imparted by the bowler’s hand, bowling may be categorized into fast, fast-medium, medium, and spin bowling [5]. However, the most important aspect of bowling is the variations due to the ball seam position. Fast and medium paced bowlers try to ensure up-right seam position [6]. The angle of ball seam is critical as it Received date: 2013−12−30; Accepted date: 2014−05−10 Corresponding author: ARIF Khalid Mahmood, Lecturer, PhD; Tel: +64−94140800 (ext. 43580); E-mail: k.arif@massey.ac.nz