Page  428 ï~~The Development of an Automatic Drum Playing Device Koichi Sekiguchi, Ryoji Amemiya, Hiroshi Kubota Waseda University Citizen Co., Ltd. Yokogawa Hewlett Packard Co.,Ltd. and Masami Yamane Waseda University Abstract This paper describes the development of an automatic drum playing device. The total system consists of a main computer, three wave-form generators, and three actuators -- two for the right and left hands that strike the snare drum, and another for the bass drum. Each actuator can simulate two kinds of human drummer's grip by changing both the position and velocity feedback gains. The score-data is processed by a score editor. As a result, the automatic drum playing device can simulate various drum-playing methods and play various songs. 1. Introduction In recent years, along with the development of electronic technology, it has become possible to play various musical instruments automatically.However most of these systems are intended not to play acoustic musical instruments but to synthesize electronic tones. The purpose of this study is to develop an automatic drum playing device which can play the snare drum like a human drummer. This device has been designed especially to follow the playing style which accompa nies the unique Scottish bagpipes. 2. Hardware The hardware system is shown in Figure 1. The actuator is designed to connect the stick's impact center directly to the shaft of a DC servo-motor at a right angle. The rotation of the shaft, whose rotary angle position is controlled, makes the stick strike the drum. The actuator can simulate two kinds of human drummer's grip by changing both the position gain and the velocity gain. One is the stiff grip that keeps the stick position firm, and the other is the soft grip that drives the stick down to strike softly. A gapsensor detects the rotary angle E 0 kfFR WAVEPC980IVX,x FMLR AMPLI[F [ER:........................!: WAVEFO.I CN/+] POGETERAI! D/A CONVERE R ~:-.x5 SCAIN,"P.......... - - - - - - - -.. - - - - - - - - - - - - - " - - -.......FEEDBACK SENH e Figure 1 Hardware System 7P.09 428 ICMC Proceedings 1993

Page  429 ï~~position and a tachometer generator detects the rotary angle velocity. The actuator has a torque of 0.165Nm/A, a frequency response up to 40Hz, and a stable striking performance of up to 24Hz. 3. Method of striking a snare drum We considered the following things to control the stick. " Intensity of the sound pressure " Timing of striking the membrane of the snare drum " Springback after striking the membrane It is evident from our study that the intensity of sound pressure is in proportion to the striking speed of the stick's tip at the membrane. As shown in Figure 2, the movement of the stick exhibits simple harmonic motion of spring with dumper. Therefore, we designed the wave-form shown in Figure 3. In this way, we can control the intensity of the sound pressure, and the timing of the striking by changing both the position gain and the velocity gain. Moreover at the moment the stick strikes the membrane, the current to the servo-motor is cut off. Doing so, the stick rebounds from the membrane naturally and the sound is heard naturally. K D Grip Figure 2 Model of striking the membrane with wood stick St ic k Step-t ime pos it ion T ime V. ave-f orm Step.....Next..step 4. Software A score editor which is capable of processing every playing sign and various playing method for the snare drum was developed. Every playing sign and various playing method are shown below. - Length of a note and a rest - Loudness notation " Designation of playing stick (right or left) Â~ An accent " Crescendo and decrescendo - Roll sound and flam,drug The main computer converts the score data to wave-form data, which determines the sound level and the strike-timing click, and sends them to the wave-form generator according to a time-base. The wave-form generator of each actuator controls the timing and the desired sound level. 5. Summary As a result, the automatic drum playing device can simulate various drum playing methods, such as single, double or triple stroke for the roll sound, and the flam or the drag for decoration notes. Therefore, by combining these methods, it can play such songs as "Scotland The Brave", "No Awa Tae Bide Awa", and so on. References [Kaneko et al., 1988] Suguru Kaneko, Masami Yamane, Hiroshi Kawagoe, Satoshi Ueda. The development of an Automatic Drum Playing Device using a DC servomotor, Publication of the JSPE 1988 Autumn Proceeding:pp483(1988). [Kubota et al., 19.91] Hiroshi Kubota, Masami Yamane, Kenjiro kawamura. The development of an Automatic Drum Playing Device, Publication of the JSPE 1991 Autumn Proceeding: pp359(1991). Fs -f. lagain H Dumper On L Off H On Figure 3 Wave-form ICMC Proceedings 1993 429 7P.09