Kajian ini berkenaan dengan pembangunan sebuah mesin pembaling bola kriket pelbagai mod. Tujuan mesin ini adalah untuk mencontohi penghantaran bola pembaling kriket manusia. Mesin tersebut mampu membaling bola secara berterusan untuk para pemukul semasa ketiadaan pembaling. Seterusnya, kajian-kajian lampau tidak menjelaskan sesetengah kriteria berkenaan dengan pembangunan mesin kriket seperti kesan bola basah terhadap kelajuan dan hubungan kelajuan antara bola dan roda. Sehubungan dengan itu, sebuah mesin pembalingan bola kriket telah dipasang siap dan prestasi mesin tersebut telah dianalisis. Berdasarkan kinematik balingan bola kriket, keperluan-keperluan reka bentuk dihasilkan sebelum pembinaan mesin. Untuk sistem kawalan, sebuah pengawal berasaskan peraturan menggunakan mikropengawal dibina untuk mengubah kelajuan putaran roda. Tiga ujian utama untuk menganalisi prestasi adalah kelajuan, jarak, dan putaran bola. Hasil eksperimen menunjukkan kelajuan bola pada tekanan udara tayar sebanyak 6.25 psi adalah 17.53 m/s dan 19.78 m/s di bawah mod perlahan dan sederhana. Konsistensi data dibandingkan menggunakan pekali variasi. Daripada hasil eksperimen tersebut, nisbah kelajuan bola dan kelajuan linear roda telah diperoleh. Disebabkan oleh kecerunan nisbah kelajuan, kelajuan bola menurun selepas kelajuan putaran tayar sebanyak 2000 rpm pada tekanan udara 6.25 psi. Selain itu, hasil trajektori daripada model matematik yang disimulasi sebanding dengan ukuran jarak dimana ralat yang diperoleh adalah 0.67% (perlahan-mendatar), 9.31% (sederhana-mendatar), dan 12.49% (sederhana-bergolek). Untuk eksperimen putaran bola, nisbah kelajuan digunakan untuk menganggarkan kadar putaran bola dengan ralat 12.32%. Berdasarkan anggaran tersebut, kadar putaran bola menurun apabila kadar putaran roda meningkat. Selain itu, simulasi-simulasi trajektori bola dengan aplikasi putaran telah dijalankan dan dianalisis. Simulasi-simulasi tersebut telah menunjukkan bahawa putaran bola menghasilkan kesan seiring dengan sistem berasaskan peraturan yang dilaksanakan tetapi magnitud kesan tersebut rendah akibat hubungan nisbah kelajuan dan sudut pelepasan asal bola daripada satah mendatar.
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This research was about the development of a multimode cricket bowling machine. The purpose of the machine was to emulate the ball deliveries of real cricket bowlers during training. Furthermore, the machine could execute continuous ball deliveries for the batsmen when the bowlers are not available. Besides that, past studies had not disclosed some of criteria related to the development of the bowling machine such as effects of wet ball on velocity and speed relationship between the ball and the wheels. In response, a multimode cricket bowling machine was fabricated and its performance analysed. Based on the kinematics of the bowling deliveries, the design requirements of the machine were made prior to fabrication. As for the control system, a rule-based microcontroller system was constructed to change the wheel’s angular speed. The three major experiments for analysing the performance were ball velocity, distance, and spin. Experimental results showed that ball velocities were 17.53 m/s and 19.78 m/s under slow and medium speed mode with best wheel pressure of 6.25 psi on both wheels. The data consistency was compared using coefficient of variation (COV). From the velocity results, the speed ratio between the ball’s translational velocity and wheel’s linear velocity was obtained. Due to the steep speed ratio gradient, the ball velocity declined after the wheels achieved an angular speed of 2000 rpm at 6.25 psi. Moreover, the trajectory results of the mathematical model simulated was comparable to the measured ball length with error of 0.67 %, 9.31 %, and 12.49 % for slow-horizontal, medium-horizontal, and medium-rolled tests respectively. For the ball spin experiments, the speed ratio equation was used to estimate the ball spin rate with 12.32 % error. Based on the estimation, the ball spin rate decreased as the wheel’s angular speed increased. Furthermore, simulations for the ball trajectory with spin applied were conducted and analysed. The simulations had shown that the ball spin produced ball trajectory effects in line with the implemented rule-based system but the magnitude of the effects was low due to the speed ratio relationship and also the initial ball release angle from the horizontal plane.
Design and development of a multimode cricket bowling machine_Fernandez Dhanaraj Davaraj_E3_2017_MYMY