Instrumentation of a Surfboard to Evaluate Surfing Performance Daniel Dezan de Bona 1,2 , Maria A. Marques 1 , Miguel V. Correia 3 1 ISEP - School of Engineering – Polytechnic of Porto, Porto, Portugal 2 IFSC - Federal Institute of Santa Catarina, Florianopolis, Brazil 3 FEUP - Faculty of Engineering – University of Porto, Porto, Portugal Abstract—This paper reports the development of a system to instrument a surfboard aiming to evaluate wave riding performance. According to the research only 3.8% - 5% of the total surfing time corresponds to the wave riding movements, despite of been the surfing goal. The system developed collects the data from twenty four force sensors positioned beneath the surfer’s feet using a microcontroller ATMEGA1280, and determines the surfer’s feet positioning and Centre of Pressure (CoP). Furthermore, an Inertial Measurement Unit (IMU) with an ADXL335 accelerometer and an IDG500 gyroscope provides information of the surfboard’s position in relation to the gravity force axis. To store the result of the acquisitions a SD Card is used. To transmit the data to an external device such as a computer, a WI-FI module complete the electronic system. A battery management was used to allow the system to work remotely. This work presents an overview of the parameter recognized in literature as influencing athlete’s performance and a brief description of the major manoeuvres in competition to figure out the parameters to be measured likewise the system developed. Preliminary tests with five different setups have shown that the force sensors to measure CoP and the electronic circuit board works properly. Index Terms—Centre of Pressure, wave riding; surfboard instrumentation; Surfing movements; remote surfing assessment. I. INTRODUCTION In professional sports practice it is common to push the body to the limit. Frequently, news is brought up about injuries suffered by athletes during competitions or training. These can be the result of hard training with incorrect techniques or without perfect knowledge of the surrounding environment conditions. The use of technology during sports practice minimizes the difference between the coach and athlete’s perceptions on the athlete’s performance [1]. By comparing the expected pattern with the movement performed, both athlete and coach are learning [2]. The use of technology in sport has been increasing considerably in the last decades, mainly due to the miniaturization of electronics, the dissemination of computers use and the decreasing costs, reducing the gap between these two fields: sport and technology. Different from most Olympic sports, although practice being equally older, surfing has a recent history as a professional sport, dating from the 80’s the beginning of professional contests. Surfing has been following the trend of using technology to increase the surfer’s performance although the major commercial developments focus on increasing the equipment quality like surfboards and wetsuits, for example. On the other hand, most scientific studies about surfing performance are focused on surfer’s injuries and physiological behavior [3-8] which seek to figure out how the surfer’s body is affected by the sport technique and which are the body responses to that kind of stimulation, which means to understand the reaction of the body for some physical external stimulus. Apart from these aspects, there are some technical studies related to paddle and stand-up movements [8-10]. This work follows from the idea left opened in literature in order to determine what type of technological innovation could help surfers increase their performance. The proposed system aims to help on this aspect by providing a real-time monitoring system which can simultaneously be of interest to coaches - to optimize the athlete’s performance by implementing a personalized training program, and to competition judges – by quantifying some of the parameters under evaluation during contests. This system is able to collect data from the surfboard, such as feet positioning and surfboard movement, to figure out the forces involved on the wave riding, accelerations and velocities during surfing activities. In this paper, section II presents an overview of the parameters recognized in literature as influencing athlete’s performance, and a brief description of the most frequent manoeuvers in competitions. Section III describes and characterizes the system operation. Finally Section IV presents some of the tests done in lab to validate the systems data and sensors calibration. A brief discussion on the expected results is presented together with the conclusion in section V. II. STATE OF THE ART A. Physiological Behavior One of the most important aspects in surfing evaluation consists on the physiological behavior of the surfer’s body. The majority of studies seek to understand the body response to the stimulus produced by surfing movements, mainly related to the paddle movement. In spite of not being the main goal of surfing, paddling corresponds to 45% - 51% of the total time spent during a surf session [8, 11]. It is also important because it allows the surfer to ride a wave in the best way possible according to his skills [12]. Farley et al.[7] concerned about the surfer’s physiological demand during two professional competitions, using a heart rate monitor, a Global System Positioning (GPS) and a time-motion analysis (using video) to acquire the heart rate data, velocity and time spent with each movement. Results shown that the average distance covered per heat was 1,605 ± 313.5 m, with an average speed of 33.4 ± 6.5 km/h, for that particularly situation. Also the average heart rate during these surf competition was 64.4% and 87.5% of the maximum heart rate registered [7]. Meir et al.[8] 978-1-4799-2024-2/14/$31.00 ©2014 IEEE Polytechnic of Porto (ISEP) in Porto, Portugal from 26-28 February 2014 2014 11th International Conference on Remote Engineering and Virtual Instrumentation (REV) Page 339