Abstract
This paper presents many common areas of interest of different specialists. There are problems described from sport, biomechanics, sport biomechanics, sport engineering, robotics, biomechanics and robotics, sport biomechanics and robotics. There are many approaches to sport from different sciences and engineering. Robotics is a relatively new area and has had moderate attention from sport specialists. The aim of this paper is to present several areas necessary to develop sport robots based on biomechanics and also to present different types of sport robots: serving balls, helping to provide sports training, substituting humans during training, physically participating in competitions, physically participating in competitions against humans, serving as models of real sport performance, helping organizers of sport events and robot toys. Examples of the application of robots in sports communities are also given.
1. Introduction
1.1 Bionics and Manipulators
For many years engineers have observed biological systems to look for inspiration to create optimized, efficient, reliable, human approved designs. At the beginning of the second half of the 20th century bionics appeared, i.e., an area of interest in technology inspired by biology. The transfer of technology from life forms to engineering started. At the centre of this process, which came up at the end of the 20th century, was always biomechanics. The reverse process was present as well because engineering products helped humans in many ways.
The first scientific and engineering approach to robots started with manipulators devoted to industry and patients. For the latter they were designed especially for the substitution of upper and lower limbs. Those manipulators were developed in the 1950s and 60s in the USA, Canada, Japan, former Soviet Russia, former Yugoslavia, and Poland [1]. In order to realize proper designs of biomanipulators, scientists and engineers needed a good knowledge of the biomechanics of humans. At the end of the 20th century Galhano and Machado [2] described the kinematic analysis of robot manipulators from a biomechanical perspective. When robots appeared biomechanics was still at the forefront of supporting sciences.
1.2 Biomechanics
Biomechanics is the science of utilizing laws of mechanics for biological systems. Biomechanics is an interdisciplinary science investigating the forces acting on living organisms and their results, i.e., stress, strains, kinetics (movement), quasi-statics and equilibrium problems.
Human biomechanics takes into account: 1) morphology aspects, i.e., the structure of the body, biomaterials, the construction of the body, geometry (in three dimensions), inertia (mass, moment of inertia, location of centre of mass), 2) function and control of body organs and systems in different tasks, 3) locostationary and locomotory movements (natural, special, with added endings, uniforms, devices), 4) control of the body and 5) interactions with the environment. One of the most important areas of interest is cooperation with the engineering, designing and manufacturing of artificial organs, manipulators and robots.
Biomechanics is utilized in everyday life, industry (ergonomics), engineering, sport, rescue, medicine, law and Earth and space transportation.
1.3 Robotics
For many years man was active in building technical devices that resembled animal or human movements, acting forces and the realisation of decisions. Those devices were designed to work better than humans did, to be stronger, faster and more precise for a long time without exhaustion, up to the capacity of energy recourses.
In the 70s and 80s of the 20th century at Waseda University in Japan humanoid robots were designed and constructed [7]. In 1986 Honda started its research program to design a robot (ASIMO – Advanced Steps in Innovative Mobility) which “should coexist and cooperate with human beings, by doing what a person cannot do” [8]. In the 1990s robots were built for operations in harsh and/or dangerous environments, e.g., space.
Humanoid robots are of great concern among scientists and engineers. They are important components in supporting society and they should play a role in personal use. They would coexist with humans and would provide support such as assistance for housework and care of the aged and the physically handicapped. They would also play a role as research tools for human science and be assistants for humans in the human living environment [7]. Important manufacturers produce biped robots that resemble the human body from morphological, functional and control approaches. Today, Honda's ASIMO robot can stand on one foot, walk on even or uneven surfaces, climb stairs and can even run [9].
In the United States, Hogan [10] presented the idea of contact robotics, i.e., machines that physically cooperate with humans. One pioneering application requiring close physical cooperation between a robot and humans is the delivery of physiotherapy to facilitate recovery after orthopaedic or neurological injury.
Today robots can be divided onto several categories, taking into account similarity, from a morphological point of view, with humans. There are: 1) anthropomorphic robots (humanoids), 2) partly anthropomorphic robots and 3) non-anthropomorphic robots.
Communication between humans and robots can be accomplished in several ways, using visible, audible or chemical cues. The visible way includes gestures (developed for robots e.g., by Schiffer et al. [11]) and face mimicry.
On November 8, 2011, Honda unveiled an all-new ASIMO humanoid robot, newly equipped with autonomous behaviour control technology. The all-new ASIMO can now continue moving without being controlled by an operator and is the world's most advanced humanoid robot [12].
2. Application Area
2.1 Sport
Contemporary sport is a phenomenon that encompasses a large part of human life. Today the aims of non-competitive and competitive sport are human health, recreation through developing fitness, entertainment, business and as a part of therapy for invalids. Forms of sport include sport for all, competitive sport for amateurs, competitive sport for professionals, sport for disabled people and sport for those with learning difficulties [3].
In many sciences, i.e., humanistic, economic, natural, engineering, health and medicine, sport is present as an applied part of them. These sciences investigate sport activity in order to improve health and to enhance sport performance in order to establish new records, but also to protect sports men and women against sport injuries.
Today sport is a large area of activity for many different kinds of people. There are sports professionals, coaches, referees, sport engineers and technicians, physicians and physiotherapists, administration personnel, organization personnel, journalists, spectators and others. Table 1 presents the main areas of each sport discipline.
Knowledge of sport [4].
2.2 Sport Biomechanics
From many sciences devoted to sport, biomechanics is the closest one to giving support to many sport areas. Biomechanics offers analyses of the body where structure (especially for disabled sportspeople), geometry (different for different sports), inertia (especially for sports divided onto categories) and potential strength, speed and control possibilities of body parts are under investigation. Training is analysed according to loads acting on the body. The recording and analysis of techniques of sports movements is one of the most important tasks of sport biomechanists. Liponski [5] presented 3000 different sports practiced all over the world, but also stated that he owns data on 8000 sports. Amongst all these sports each has its own technique. Another area of interest is the tactics of sport. This relatively new problem investigated by biomechanists offers improvement in sport activity according to, for example, the distribution of loads along the whole course of the sports track or the whole match played by competitors.
Diagnosis of sport performance can be done using sophisticated equipment, such as devices for the measurement of body dimensions and muscle strength as a function of time, electro-goniometers and accelerometers, force platforms and pressure distribution transducers, high speed cameras and motion capture selective cameras, full body measurement systems and global navigation satellite system (GNSS).
The great advantage of sport biomechanics is the possibility of measuring the loads and movements of competitors, not only during training sessions, but especially during competitions. Biomechanists using different kinds of cameras and sensors attached to sport equipment and sometimes to the body of a sportsperson can monitor sport performance in a real competition. They can offer many different analyses to the sportsperson, a coach and all others interested.
The future of sport biomechanics appears to be very positive. With the miniaturization of sensors and amplifiers, good communication between the sportsperson, coach and sports analyst (e.g., like in motor sports), faster computers with a wider range of application software and with a wide range of sport robots better sport results will be easier to achieve.
2.3 Sport Engineering
Engineering can offer many interesting devices to sportspeople that can enhance sports results. Within sport engineering there are products devoted to: a) the body, e.g., skin covers, garments, accessories and genetics, b) movable products, e.g., equipment, vehicles, requisites and tools, c) immovable products, e.g.. appliances, stands, rooms and facilities, d) information technology, e.g., computer hardware and software, communication and journalism devices and e) miscellaneous products, e.g., security, trophies and gadgets [6].
Many sports disciplines, in order to improve results, utilize new materials (for example for the pole in pole vault), aerodynamic garments, more durable equipment and faster vehicles. There are technical devices used especially during training, such as manikins in judo and wrestling, body supports in gymnastics and acrobatics and simulators in automobile and aeroplane sports. There are other devices used only during competition, especially referee devices. During both training and competition special robots can be utilized.
3. Methods Used and Co-existence of Biomechanics and Robotics
Biomechanics and robotics have several common areas of interest. Both are based on mechanics, take into account body build and use the generation of own forces to propel the system. They are involved in investigations into the interaction of the systems with the environment. Both use dynamics sensors for acquiring and transferring forces/moments of forces and take into account control processes.
In order to acquire kinematics data, robot designers can use motion capture technology that is used by biomechanics specialists. Here contrast markers are put on the body or the face (from few, up to more than 100 of them) to capture movement of the body or the face.
Several institutions within their scientific work take into account both biomechanics and robotics. For example, there is a biorobotics laboratory in the Department of Biomechanical Engineering at the Technical University in Delft, the Netherlands [13]. There is a biomechanics and robotics laboratory in the Department of Bioengineering at Imperial College London, UK [14]. Biomechanics is also well developed at Warsaw University of Technology, where at first biomanipulators and then robots were designed [15].
There are scientific meetings and articles devoted to combined biomechanics and robotics. In 1999 at the University of Heidelberg there took place an international symposium called “Biomechanics meets robotics. Modelling and Simulation of Motion” [16] and in 2005 the conference was organized on “Fast motions in biomechanics and robotics” [17]. Hogan [10] presented a plenary lecture on “Biomechanics and Robotics” during the 10th International Conference on Climbing and Walking Robots and the Supporting Technologies for Mobile Machines (CLAWAR), which took place in Singapore in 2007. Within the programme of the 33rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society in Boston (2011) there was a session named “Biomechanics and Robotics” [18]. At another conference of the International Association of Science and Technology for Development, held in Pittsburgh in 2011, there was also a session combining biomechanics and robotics.
4. Current Status of Sport Biomechanics and Robotics
Sport is a human activity where the body is involved in the development of fitness, technique and tactics during training and competition. Based on this, one should differentiate between sport, sportspeople versus robots and robo-sport. Sportspeople versus robots is a human physical activity with sport rules where opponents are machines called robots. Robo-sport is the physical activity of machines that can participate in a sport-like competition in order to win.
In order to build robots for application within sport one needs data on mechanical sport performance. These data can be obtained from sport biomechanists who investigate the movement of sportspersons and sport equipment. Kinematic data on displacement, velocity and acceleration and also dynamic data on force, moments of force and force impulses should be taken into account for implementing the mechanisms of robots and also to control them.
There are several types of sport robots based on the biomechanical approach. Below some of these types are presented:
robots helping in providing sport training
robots substituting humans during training
robots serving as models of real sport performance
robots participating in competition against humans
robots helping organizers of sport events
Robotics as relatively new area has had moderate attention from sport specialists. It should be presented to them in a simple way, since sport specialists are usually not technically educated.
5. Results
5.1 Robots Helping in Providing Sport Training
An electric walker warns those training on a treadmill if they are working too hard or not hard enough and proclaims any speed or inclination. It measures heart rate by a sensor in the handle. It is foldable when not in use [19].
A Backyard Automated Driving Range is a golf training system for training in any conditions. A ball dispenser holds up to 150 balls. A tented net is made from durable nylon [20]. A robocup works by searching for a golfer's ball in any terrain but at a short distance of just a few metres. It returns balls during practice training [21].
5.2 Robots Substituting Humans During Training
In the 1990s Toshiba had developed a robot arm for manufacturing that could also play table tennis (Fig. 1a) or other racket ball games (Fig. 1b). In 1997 Toshiba unveiled the Beach Volley Ball Playing Robot as part of their vision for human-friendly robots (Fig. 1c). These robots were counter-partners for humans during their training.
Toshiba robotic arms that could play ball sports with humans: (a) and (b) – first versions. (c) – version since the end of the 20th century [22].
Another example of a table tennis robot is placed at the edge of a table and sends balls to the player at the other side of a table [23].
BumperNets Robo-pong is a robot that can help a player as a trainer and practice partner from a beginner's level through intermediate to an advanced player. There is an option of ball recycling, where the robot reuses the balls it receives from the player. The head of the robot, which serves balls, can move left and right so that the player receives balls from different sides of the table [24] (Fig. 2).
Example of a robot which substitutes a player at table tennis. A player can play balls served by a machine (a) where is apparatus serving balls (b). One can adjust the speed of a ball, ball frequency, oscillation speed of a moving apparatus serving balls [24].
The Swing shot tennis robot [24] has the ability to serve balls at a variety of speeds, as well as a variety of pitches, such as spin, lob and smash (Fig. 3a). The Jada badminton robot [24] serves shuttlecocks with a speed of about 80m/s (300km/h) on the badminton court (Fig. 3b)
Examples of: (a) robot serving tennis balls using a real racket; (b) robot serving shuttlecocks [24].
Sport robots are also machines that can be in physical contact with a sportsperson. They play the role of a partner (e.g., in acrobatics) or an opponent (e.g. in contact (especially combat) sports) (Fig. 4).
Robot substituting real competitor with springs inside opposing action of attacker (International Sport Science Institute, Yong In City, Korea) [25].
5.3 Robots Serving as Models of Real Sport Performance
At the beginning of the 1980s the author of this paper took part in the research at Pennsylvania State University, where wooden and aluminium bats were compared. A ball was released from a pneumatic gun under high pressure and a bat was released in an angular movement with the thrust of a spring. The hitting instant of the bat against a ball was filmed from above. In order to demonstrate the latest advances in high-speed industrial technology, researchers at the University of Tokyo have created a baseball-pitching robotic arm against a mechanical batter with near-perfect swing (Fig. 5).
The baseball robot used for investigations of bat-ball interaction: (a) accelerating a ball by artificial upper extremity; (b) striking a ball by the bat [24].
5.4 Robots Helping Organizers of Sport Events
In 2011 a robot called Robonaut 2 built by NASA and Chevrolet engineers helped to select the most valuable player (MVP) for the American Superbowl. During the show the robot was kept behind a table so that nobody would notice he was legless [26].
5.5 Robots Physically Participating in Competition against Humans
The Enhanced Automated Robot Launcher (E.A.R.L.), a bowling robot of the second generation, was placed at the International Training and Research Centre (ITRC) in Arlington, Texas. It can consistently toss a ball at a speed of about 4–10m/s. The robot participated in a game against a bowling star. This bowlbot lost the game 209:259. E.A.R.L. will be used to help design lanes, balls and pins [27].
William Garage developed an intelligent machine that could be the ultimate pool-playing companion for a human being. The robot, PR2, has a head resembling a Polaroid camera and arms that resemble assembly units. In the past pool playing machines relied on overhead cameras to calculate moves and execute them. William Garage's pool playing robot relies on the standard rules of pool: shooting the cue ball from where it lies on the table and having the same vantage point as a human player would. PR2 has a high-resolution camera with a colour ball tracker that helps the robot to differentiate the balls and locate them on the pool table. In order to hit the cue ball, the team at William Garage created an innovative bridge and grip to allow the robot to hold a pool-stick and generate power through its wrist (Fig. 6).
The robot PR2 for pool-playing against humans [24]
Sports robots as counter-partners can be utilized in individual sport games. Robot can be a table tennis-player that plays a game with a human player. Here the robot's cameras look continuously at the ball, in order to position the robot's body in the proper place and then use a manipulator as an upper extremity with a hand equipped with a racket to rebound the ball. A team of Vietnamese and Chinese researchers from Zhejiang University introduced “Topio”, a 1.6m tall robot that can analyse a ball's path. Its abilities include serving fore and back-handed, returning and scoring. The project took 4 years to complete [28].
5.6 Robots Physically Participating in Robo-sports
In 2006 in Catania, during a Eurobot competition, pairs of robots competed against one another on a golf course. However, theirs wasn't a true golf course, it more closely resembled a bordered tennis court with colour-coded holes punched in it. Teams of two robots worked together to sink the coloured (table tennis) balls they had been assigned [29].
Sony Corporation built a robot (AIBO), which can play a football match. Some robots were guided by their masters with the help of remote controls and others were programmed to respond to the moving ball. Scientists from Tokyo University constructed a robot that could jump vertically and land smoothly on its own legs. The knees of the robot include pneumatic actuators as artificial muscles. A robot of 120cm and 10kg mass can jump half a metre up [30].
Honda's ASIMO humanoid robot is 120cm tall and is equipped with autonomous behaviour control technology. ASIMO can continue moving without being controlled by an operator. It has significantly improved intelligence and the physical ability to adapt to situations. From a mechanical point of view ASIMO is one of the most advanced humanoid robots ever developed. One of its abilities is standing on one foot (Fig. 7a). However, it has some limitations; any kind of physical work is difficult for ASIMO. It is not as strong as General Motors/NASA Robonaut 2, which is able to lift 10kg with a single arm. Unfortunately Robonaut has no lower extremities. [12, 22]
In 2010 four robots presented their skills during a football match at the CeBIT exposition [23]. They used colour and lines to see an orange ball, pitch it towards green and head for the yellow and blue goals (Fig. 7b).
RoboCup is the robot version of the World Cup (football/soccer) and the (self-proclaimed) “most important robot contest in the world.” RoboCup has several different classifications for robots, which include small-sized, middle-sized, four-legged robots and humanoids. The organizers chose soccer because it uniquely tests how human a humanoid really is. It requires developers to use a broad range of technologies and figure out how to put them together into a cohesive, working whole [32].
In the United States Robot Football League (or RFL as it is called) exists. The rules of RFL mimic American rules football. Teams can be from 3 to 6 players (Fig. 8).
Robots participating in a match play of American Robot Football League: (a) robots on wheels; (b) the touchdown [24].
5.7 Sport Robot Toys
At the Stanford Education Program for Gifted Youth (EPGY) Summer Institute a hockey robot called MANOI has been created. It can move forward and backwards several times and shoot a few times [23].
Nemec and Lahajmar [33] presented a ski robot which was capable of autonomous skiing on a ski slope using the carving skiing technique. The aims of the work were to design the control and navigation of a ski-robot. Based on a complex sensory system, it is capable of autonomous navigation between race gates, can avoid obstacles and maintain a stable position during skiing on a previously unknown ski slope (Fig. 9).
Ski robot: (a) – design; (b) – on a slope [33].
During the Football World Cup in South Africa (2010), the Danish Embassy in Tokyo established a robot cheerleader to help support its team [23].
Cleatus Fox Football Robot is the official mascot of the Fox National Football League in the United States. It can do a lot of things, from touchdown celebrations to showing off his karate moves and can even throw up a ball [24].
6. Further Research
The sport robots area is well developed. About 300 robots from 86 teams participated in the eighth National Robot Soccer Contest in Wuhan, the capital of central China's Hubei province, on May 14, 2007 [34]. Eurobot 2006 featured 120 robots that represented 128 different countries [35]. The RoboCup scheduled for 2010 was held in Singapore. The event hosted 500 teams from 40 countries. The goal for the future is “By the year 2050, develop a team of fully autonomous humanoid robots that can win against the human world soccer champion team.” [36].
Man-robot interaction is a psychological issue too. People must be accustomed to machines that are close to them, observe them and in the area of sport are better than people because they are more precise, with more strength, are not exhausted and are without stress problems.
The future of sport will develop in several ways. Some sport disciplines will be without robots, just humans participating in a competition, others will partly allow the presence of robots e.g., as goalkeepers and others will be as it is already now, only robots will compete, alone or against each other.