Abstract:
The invention is based on the use of pneumatic systems for the conversion of human power of children&#39;s play. The energy of the compressed air can then be converted to electricity for purposes such as lighting and communication. This provides a low-cost, low-resource means of generation of electricity, especially for use in developing countries. This embodiment is an extension of the invention by generating electricity from the pedaling action of an exercise bicycle while playing a video game and includes the use of a stationery exercise bicycle, a video gaming system, a monitor, a game controller including buttons/joystick on the bicycle, electromechanical and biomedical sensors, an artificial intelligence-based pre-processor for signals from the controller, and a pneumatic or electromechanical energy conversion device for producing electricity. The electricity produced can be used to quantify the play or exercise involved, and to provide incentives to encourage sustained play or exercise.

Description:
CROSS-REFERNCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation-in-part of U.S. application Ser. No. 10/369,081, filed on Feb. 18, 2003 and entitled Pneumatic Human Power Conversion System Based on Children&#39;s Play. 
     
    
     TECHNICAL FIELD  
       [0002]     The invention described in “Pneumatic Human Power Conversion System based on Children&#39;s Play” is based on the use of pneumatic (i.e., compressed air) systems such as cylinders, motors, valves, and regulators for the conversion of human power of children&#39;s play in school playgrounds and other public places. The energy of the compressed air can then be converted to electricity for purposes such as lighting and communication. This provides a low-cost, low-resource means of generation of electricity, especially for use in developing countries.  
         [0003]     The present invention is an extension of this invention by combining video game play with an exercise bicycle for conversion of human power into electricity. The invention includes the use of a stationary exercise bicycle, a video gaming system, a television or computer monitor, a game controller including buttons/joystick on the bicycle, electromechanical and biomedical sensors, an artificial intelligence-based pre-processor for signals from the controller, a pneumatic or electromechanical energy conversion device for producing electricity, a signal conditioner to quantify the exercise done, and a recording/printing device to provide incentives proportionate to the exercise. Children and adults can play games, individually or in groups, on the console by pedaling and isometric exercise, and the power conversion subsystem produces electricity in excess of the energy used to operate the overall system.  
         [0004]     The system can be used in homes and schools, public playgrounds, athletic clubs, video game arcades, and places like fast-food restaurants and shopping centers to encourage children and adults to indulge in physical activity combined with the entertainment of video gaming. The system can also be combined with educational software. The power produced can be used as a backup power source—especially in developing countries—as well as a quantitative measure of physical activity with a view to providing incentives or rewards to people to exercise actively.  
       BACKGROUND OF THE INVENTION  
       [0005]     The use of pedal power and exercise machines to generate electricity for powering appliances is nearly a century old, as discussed by Seelhorst and McCullagh. A patent for a device that generates electricity from stationary bicycle for viewing television was issued to Holmes in 1981 (U.S. Pat. No. 4,298,893). More recently, this method has been used by some engineer-volunteers to provide Internet access to a village in Laos without electric supply (Applewhite). Pedal power has been harnessed through pneumatic means by Tsukagoshi et al as an emergency power source during earthquakes.  
         [0006]     Several inventors have proposed the combination of exercise machines and video games over the years. In U.S. Pat. No. 4,512,567, an exercise bicycle is used in conjunction with a video game, the control signals to the game being provided by pedal speed sensors and handle bar motion sensors. Action switches are also attached to the handle bar for input to the video game.  
         [0007]     U.S. Pat. No. 4,711,447 presents a similar exercise apparatus with inputs to the video game provided by the pedal and handle bar motions. Further, the chair and assembly positions are fed back, and mechanical friction elements are used for user adjustment of the exertion levels.  
         [0008]     A combination exercise and video game system is proposed in U.S. Pat. No. 5,362,069, in which in addition to motion sensors the heart rate signal is measured and fed back to modify the exertion level of the game.  
         [0009]     Jarvis (U.S. Pat. No. 5,577,981) developed a virtual reality exercise system with a fixed support frame and movable components with which exercises were provided to the user by employing a video system. Jarvis employs a video camera as well as position and force sensors for supplying real-world information to the virtual reality (VR) system.  
         [0010]     Ohsuga, et al (U.S. Pat. Nos. 5,997,439 and 6,244,987) have invented VR exercise systems for wellness therapy. In &#39;439, for bed-ridden patients the virtual reality environment is modified by physiological and psychological measurements. In &#39;987, a range of stimuli are provided such as sight, hearing, touch, and smell in the control of the VR environment.  
         [0011]     Recently, a commercial game controller called Kilowatt for the Xbox, PS2, and PC games has become available. It is essentially a game pad providing isometric exercise for the player while playing video games with commercial consoles (Hermida).  
         [0012]     Initially, the present invention was developed for the purpose of harnessing the collective energy of a number of children to create a large power output sufficient for continuous operation of several lights, fans, and communication equipment for a long time. The premise being that the power is produced as part of play and therefore separate, deliberate effort is not required to produce power. The proposed approach involves low cost: a clockwork radio producing a few watts of power generally costs $50 or more. For the cost of a few hundred dollars, the hardware for the play-based power harvesting system could produce several hundreds of watts of electricity.  
         [0013]     The invention is eminently suited to developing countries where the main constraints are cost, ruggedness, and low-resource and skill requirements (cf. piezoelectric or storage capacitors). A natural extension of this invention is to harness such power indoors by combining video game play with exercise bicycles.  
         [0014]     Several inventions have sought to combine exercise systems with the entertainment aspect of video games as well as advanced technologies like virtual reality. These inventions have the advantage of reducing the monotony of repetitive exercise and make it fun and entertaining. Some inventions have also combined video gaming with physical therapy in order to reduce the drudgery of therapy to disabled persons.  
         [0015]     Use of pedal power from stationery bikes to produce electricity was proposed nearly a century ago. In the early part of the 20 th  century, pedal power was used in remote locations to produce electricity to watch television. Other forms of human power conversion have been proposed in recent years, e.g., hand cranking to power radio, flash lights, and cell phones, and foot wear fitted with power conversion devices to operate wearable computers and portable electronics.  
         [0016]     While all the above inventions require deliberate effort and produce limited amounts of electricity, this invention of a pneumatic human power conversion was proposed based on children&#39;s play. The novelty of this invention is that it does not require deliberate effort and produces significantly more amounts of power, sufficient to operate appliances. Electromechanical alternatives to the pneumatic power conversion subsystem were also proposed.  
         [0017]     These playful energy converters are based on outdoor playground equipment where the children are stationery with respect to the equipment, e.g., seesaw, swing, and merry-go-round. A drawback to this invention is that reliable operation of the outdoor play equipment requires expensive weatherproofing and the children&#39;s play depends on favorable weather conditions.  
         [0018]     By contrast, pedal power conversion produces more power, is more efficient, can be done indoor with simple power conversion apparatus, and can also involve exercise activity by adults. However, continuous operation of the bicycle over a long period is felt to be monotonous by both children and adults. Therefore, as an extension of the original invention, it is sought to extend the playful energy conversion idea to the case of combination of pedal power conversion accompanied by video game play.  
       SUMMARY OF THE INVENTION  
       [0019]     The present invention combines the pedal power-based electricity generation method with the video gaming technique, to develop a source of significant amounts of electric power both as a source of energy and as a measure of physical exercise to provide incentives to the participants.  
         [0020]     The artificial intelligence-based pre-processor for signals from the game controller is a crucial part of the new invention. The reaction times for video games with the exercise system will not be as fast and sustained as for the hand-operated conventional controllers, due to the physical exertion involved. Moreover, where persons of different physical capacities participate in multi-player games (e.g., parents and children, or bigger and smaller children), the smaller or younger players will be at a disadvantage.  
         [0021]     Therefore, in the general case the pre-processor will be used to “speed up” the responses of the players before the controller commands are sent to the game console. For multi-player games with players of unequal physical capabilities, the pre-processor can be used to “equalize” the commands from the individual controllers in a fair manner so as to render the gamers competitive. Of course, this amounts to using software to “cheat” the game software; however, the main goal of the invented system is not video gaming per se, but to use the entertainment element of video gaming to sustain physical exercise and power generation.  
         [0022]     If the pre-processor is provided with visual information on the progress of the game, then it can actively assist the player in the game. Otherwise, the processing of the signals from the game controller will mainly be anticipatory and heuristic. However, custom-made video game software for the system can be specifically designed taking into considerations knowledge of optimal exercise patterns and energy expenditure patterns for the players. In this case, the game software will modify the progress of the game (e.g., make it easier to win) so as to encourage the player to exercise to the utmost extent.  
         [0023]     The intelligent pre-processor can also be used in a “learning” mode for specific participants; either based on input information (such as name or age and weight) or sensed information such as weight of the participants (using force sensors attached to the bike seat). In this mode, the pre-processor would then modify the command signals sent to the console or modify the mechanical impedances interfaced to the user so as to sustain a preferred pattern of exercise over a short-term or long-term period.  
         [0024]     The advantages of the extended invention are manifold:  
         [0025]     1. It can produce more power compared to the outdoor playful human power converters based on teeter totter, swing, and merry-go-round and is also more efficient being based on video game play on stationary bicycle.  
         [0026]     2. Both adults and children can use it, e.g., parents can play with their children on multiple bikes and game controllers connected to a single console-monitor system.  
         [0027]     3. Since off-the-shelf video game software can be readily used with the proposed invention, continued operation of the system over long periods of time can be achieved because of the entertainment value of the video game.  
         [0028]     4. Motivation to indulge in exercises is increased by cooperation or competition from partners-in-training. Therefore, at homes, schools, and other public places, multi-player video gaming based on the proposed invention can lead to increased participation in exercises. This will lead to better physical fitness in the long run and reduce obesity.  
         [0029]     5. Educational personal computer software for children shares many similarities with video games. Therefore, the proposed invention can also be implemented in conjunction with educational software, to combine both physical and learning activities.  
         [0030]     6. While the pedal power system is most suited for games such as racing, it can also be combined with other types of games (e.g., fights or battles) by combination with passive (e.g., springs or dampers) and active (e.g., actuators with variable impedance elements) mechanical devices.  
         [0031]     7. In the context of developed countries where energy is available abundantly and at affordable prices, the electricity produced can be used mainly as a quantitative measure of physical activity and thereby to provide incentives or rewards to children and youth to exercise, e.g., in schools, video game arcades, shopping centers and fast food restaurants. On the other hand, in the developing countries the invention can be used in schools and other pubic places as a source of back-up power to operate basic appliances such as lights, fans. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0032]      FIG. 1  illustrates a preferred embodiment of the present invention wherein the energy conversion is compressed air energy storage based on a seesaw using an air motor.  
         [0033]      FIG. 2  illustrates a continuation of the system in  FIG. 1  showing the transmission of compressed air to power generator and showing the power generation from compressed air.  
         [0034]      FIG. 3  illustrates a preferred embodiment of the present invention wherein the energy conversion is compressed air energy storage based on a seesaw using a slider-crank mechanism.  
         [0035]      FIG. 4  illustrates a preferred embodiment of the present invention wherein the energy conversion is compressed air energy storage based on a swing using a pneumatic rotary actuator.  
         [0036]      FIG. 5  illustrates a preferred embodiment of the present invention wherein the energy conversion is compressed air energy storage based on a merry-go-round using an air motor.  
         [0037]      FIG. 6  illustrates a preferred embodiment of the present invention wherein the energy conversion is compressed air energy storage based on a merry-go-round using a crank-slider mechanism.  
         [0038]      FIG. 7  illustrates a preferred embodiment of the present invention wherein the energy conversion is based on a seesaw using an electromagnetic generator.  
         [0039]      FIG. 8  illustrates a preferred embodiment of the present invention wherein the energy conversion is based on a swing using an electromagnetic generator.  
         [0040]      FIG. 9  illustrates a preferred embodiment of the present invention wherein the energy conversion is based on a merry-go-round using an electromagnetic generator.  
         [0041]      FIG. 10  illustrates a preferred embodiment of the present invention wherein the energy conversion is of the electromechanical type based on a stationary bike on which the player exercises while playing a video game on the console. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0042]      FIGS. 1 and 2  illustrate the basic principle of the new invention. For simplicity, we limit our discussion to power conversion based on a seesaw. The cases of a swing and a merry-go-around can be considered similarly.  
         [0043]     In  FIG. 1 , the seesaw  10  is often supplied with hard cylindrical helical springs  12 ,  14  to smoothen the actions of the seesaw mechanism. In the present mechanism, instead of the springs we employ two pneumatic cylinders  16 ,  18  on the two sides of the seesaw. To prevent any accidents and injuries to players&#39; limbs from the moving pistons, we provide a bellows-type flexible sheath between the bottom of seesaw and the top of the cylinder as shown  20 ,  22 . The outer bodies of the cylinders would get heated due to the compression of air inside. This would require shielding of the outer bodies too (not shown here).  
         [0044]     To simplify the system and make it portable, the bottom end of the cylinders can also be fixed to the central support of the seesaw, rather than being fixed to the ground.  
         [0045]      FIG. 2  shows the process of compression of air and its transmission to the power generator stage. For improved compression rate, we consider the case of double acting cylinder. The atmospheric air enters the cylinder input ports  24 ,  26  alternately through check (or plate) valves  36 ,  38 . The reciprocating vertical motion of the piston  34  of the cylinder  32  under the motion of the seesaw results in compressed air being outputted through check valves  40 ,  42  via output ports  28 ,  30  to the pipeline through a union tee joint  44 . Reference numeral  46  indicates that the pipeline could be very long. The compressed air from the pipeline is stored in an air tank  48 . Essential parts of the air tank, such as pressure gage, pressure release valve, regulator, etc are not shown here for simplicity.  
         [0046]     When the compressed air inside the air tank reaches a set pressure level, the on-off valve  50  is opened. The air is passed through a filter-regulator-lubricator unit  52 . If the pressure of the stored air is low due to pressure drop along long pipeline, then an air booster  54  can be used to reduce the volume and increase the pressure of the air to the power generator unit.  
         [0047]      FIG. 2  also illustrates the generation of power from the compressed air. The compressed air from the pipeline  56  is used to actuate an air motor  58 . The electric generator  62  is coupled to the air motor  58  through a gear train  60 . The resulting motion of the electric generator produces an electric current through the cables  64 , which is used to charge the battery  66 .  
         [0048]     In general, air motors are very expensive compared to air cylinders and moreover require extensive gearing. Therefore, to reduce cost we can simply use compressed air from the pipeline  56  to actuate a cylinder which in turn can be used with a slider-crank mechanism to move the electric motor. The operation of this mechanism is shown in  FIG. 3 .  
         [0049]     Here, compressed air from air tank  48  is fed through pipeline  56  to an intake/exhaust valve  68  driven by crank shaft  74 . For simplicity, the components shown in  FIG. 2 , viz., on-off valve and filter-regulator-lubricator unit are not shown here.  
         [0050]     The compressed air drives a piston  72  housed in a cylinder  70  and attached to the crank shaft  74 . A flywheel  76  is attached to the output shaft  78  of the crank shaft. A gear train  60  is connected at the end of the output shaft, and an electric generator-battery-wires combination as shown in  FIG. 2  is used to generate electricity.  
         [0051]     In the case of harnessing human power of children playing on a swing, a pneumatic rotary actuator can be used as the compression mechanism.  FIG. 4  illustrates this case. Here, a rigid arm  86  is connected through a swing pivot  88  to the top cross bar of the swing  80 . The swing seat  82  is connected to the rigid arm  86  through the flexible chain  84 . The use of the rigid arm allows the capture of a large portion of the torque of the swing&#39;s movement. The top end of the rigid arm  86  is fitted with a sector gear  90 , which is connected to a rack gear  98  connected between the pistons  96  housed inside a cylinder  94 . Two actuators are used, one at each end of the swing.  
         [0052]     The rotational movements of the swing during children&#39;s play result in compression of air in the two closed chambers of the cylinder. The compressed air is released to the storage and power conversion section through output ports  100  under the control of check valves  40  and  42 . The compressed air storage and power conversion sections are similar to those shown in  FIG. 2  for the use of an air motor.  
         [0053]     Here again, rotary actuators are expensive and therefore a pinion-and-rack gearing mechanism can be used to actuate a double acting cylinder for compression of air. The mechanism shown in  FIG. 3  may be used for this purpose.  
         [0054]     Air motors could be used in the case of merry-go-rounds for compression.  FIG. 5  illustrates this case. In the top view, the merry-go-round is shown transparent for clarity. A large diameter drive pulley  104  is connected to the bottom of the rotating disk  112  of the merry-go-round  102 . A V-belt  108  moves along the drive pulley  104  due to the rotation of the merry-go-round. The V-belt passes over a motor pulley  106  whose shaft is connected to the air motor  110 . A tensioner pulley with spring  114  is used to maintain the torque on the air motor.  
         [0055]     Here too, due to cost considerations it will be preferable to use crank-slider mechanism (as used in positive displacement reciprocating piston-type compressors) with an air cylinder.  FIG. 6  illustrates this case. Here, two double-acting cylinders  118  are mounted on a support platform  120  below the rotating disk  112  of the merry-go-round  102 . A crank  124  is attached to the bottom of the center post  116 . Two cylinders are used with their pistons  126  connected to the crank  124  through connecting rod  128  to the center post  122 .  
         [0056]      FIG. 7  illustrates the use of electromagnetic generators to harness the power children&#39;s play on the seesaw  10 . A cable  130  runs through pulleys  132  attached to the bottom of the seesaw at the ends. The cable is wound once the simple pulleys to ensure friction. Further, a spring  136  is used with the cable to maintain tension in the cable. Gear motors  134  are coupled to the shaft of the pulleys and the cable ends are anchored to the ground at  138 .  
         [0057]     The use of electromagnetic generator to convert the power from the swing is illustrated in  FIG. 8 . As in the pneumatic conversion case (shown in  FIG. 4 ), the sector gear  90  is used, coupled to the rigid arm  86 . A gear motor  142  is coupled to the shaft of the upper gear.  
         [0058]      FIG. 9  illustrates the use of electromagnetic generator in connection with a merry-go-round. The mechanism is identical to the case of pneumatic conversion with air motor (shown in  FIG. 5 ), except that a gear motor  144  acting as a generator replaces the air motor.  
         [0059]     The up and down motion of the seesaw, and the to and fro motion of the swing results in alternately positive and negative voltage to be generated at the terminals of the gear motors, which acts as a generators. Therefore, an ac-to-dc rectifier will be used to generate a dc voltage for charging the battery (not shown for simplicity).  
         [0060]     To reduce maintenance and improve the performance, it is necessary to filter the air entering the compressing cylinders. This is particularly so because air in the playground atmosphere is dust-filled. However, coarse air filters may be sufficient in most cases unlike in precision industrial operation. In practice, trade-offs between cost of air filters and cost of maintenance of low-cost cylinders may also be considered.  
         [0061]     Finally, it may be mentioned that human power conversion is easily achieved from children&#39;s play under conditions where the children are static relative to the moving mechanism such as seesaw. Where the children are in a dynamic state relative to a static mechanism (e.g., slide) it will be difficult, though not impossible, to employ human power conversion techniques due to considerations of safety and simplicity.  
         [0062]     The main alternative to the present pneumatic approach for human power conversion based on children&#39;s play would be to use electric (i.e., electromagnetic) generators. This method has the advantage of higher energy efficiency. However, as mentioned before it is constrained by the hazards of electric shock and leak hazards in children&#39;s playgrounds or meeting places. In fact, pneumatic motors are preferred over electric motors in applications such as opening and closing of aquarium tank doors for this same reason.  
         [0063]     Minor variations of the pneumatic approach could also be implemented in practice: e.g., use mini gas turbines run by compressed air to move electric generators. However, for the kind of low-pressure energy storage system considered here, the reciprocating cylinder-type system is more economical and simpler to use.  
         [0064]     Other approaches to producing renewable electricity for schools would be to install solar panels or wind turbines. However, the costs of these techniques would be far higher than those for the proposed invention.  
         [0065]     In recent years, energy use/scarcity has become a serious problem due to depletion of non-renewable energy sources, increasing population, environmental pollution, and Global Warming. While in developed countries, the energy problem is one of short-term scarcity or optimum use, an estimated 40% of the world&#39;s population—or, 2 billion people in the less developed countries—do not have even have access to electricity. Moreover, this number is expected to double by the year 2050.  
         [0066]     While the costs of solar, wind, geothermal, etc energy generation are coming down gradually, they are still beyond the reach of people in many developing countries, where majority of the population earns per capita incomes of less than a dollar a day. They do not have access to capital, technology, and resources such as oil, coal, or nuclear material. Even where there is an electricity grid, long-duration power outs are very common, particularly in summer when the rivers run dry.  
         [0067]     Therefore, the invention outlined here could be used in playgrounds to provide very low-cost electric power for basic needs such as lighting, fans, and communication. The technology of compressed air involved is fairly simple, and well within the skills of technicians in developing countries. The material requirements are also fairly minimal: cylinders (variant of bicycle pumps could be used), valves, rubber or PVC pipelines, low-cost pressure gages and regulators, etc. The systems can easily be maintained and upgraded or repaired.  
         [0068]     The use of the new technology also offers two significant side-benefits to children in developing countries: first, the promise of low-cost guaranteed electric power would encourage the introduction of reasonably well-equipped, safe and ergonomically designed play equipment in their schools and meeting places. Secondly, use of air filters as part of the compressed air systems could help reduce some of the air pollution in their school/background environments. The hybrid pneumatic-gasoline car invented by Guy Negre is similarly being adopted in high-pollution cities in Mexico and other developing countries because it acts as a negative emission vehicle, using atmospheric air for compression through on-board air filters.  
         [0069]     Future modifications of the new invention also will have potential applications in a hi-tech setting, e.g. as a power source for wearable computing, emergency power source during earthquakes, and power assist for the elderly and handicapped.  
         [0070]     Theoretical and experimental studies can be conducted to optimize the design of the proposed system, e.g., sizing of components, location of play equipment, etc.  
         [0071]     The present invention has fairly limited application in developed countries where cheap and abundant electric power is readily available. The main potential for this invention lies in developing countries, where electricity supply is non-existent, erratic, or expensive.  
         [0072]     The technology behind the new invention could be deployed on a wide scale in developing countries, with the manufacturing of the systems by local companies. Labor and materials will be a major part of the expenses involved, and local conditions would have a significant influence on the installation and running of the final systems in schools and playgrounds.  
         [0073]     The proposed systems can also be used for play by children at homes, contributing an alternative source of power.  
         [0074]     In  FIG. 10 , the player  210  pedals on a stationary bike  212 . The rear wheel is free to rotate, and with the tire removed the wheel rim  214  can be used as a large diameter pulley. A v-belt  216  moves along the rim  214  due to the rotation of the wheel under the pedaling action. The v-belt  216  passes over a motor pulley  218  whose shaft is connected to a gear motor  220 . The fixed attachment of the motor-pulley combination is not shown for simplicity. As is well known in the art, a tensioner pulley with spring can be used to maintain tension in the v-belt.  
         [0075]     The electricity produced in the motor  220 —acting here as a generator—is measured by a signal conditioner  222  and used to charge a battery  224 . Occasionally, the player  210  will be required to pedal in reverse. In this case, if the rim  214  is arranged so as to move in reverse, an electric voltage of opposite polarity will be produced. This voltage can either be blocked out using a diode, or a rectifier can be used to reverse its polarity before charging the battery.  
         [0076]     A potentiometer  226  is attached to the center of the handle bar  228 , to sense the left or right turn angle of the handle bar  228 . Action buttons  230  are attached at either end of the handle bar  228 . The player  210  presses on them either intermittently or continuously during play. A force sensor  232  is attached to the bike&#39;s seat  234  so that the weight of the player  210  can be estimated using suitable signal conditioning circuitry. A heart beat sensor  236  is also used, and a rotary encoder  238  is attached to the shaft of the pedal  240 . The encoder  238  is used to estimate the speed, direction and forward/reverse displacement of the pedaling.  
         [0077]     Thus, the sensors  232 ,  236 , and the action buttons or switches  230  are used to simulate the joystick and buttons on the conventional game controller. The signals:  242  from the potentiometer  226 ,  244  from the action switches  230 , and  246  from the rotary pedal encoder  238  are fed to the game controller  248 . The signals  250  from the heart beat sensor  236 , and  252  from the force or weight sensor  232  are fed to the intelligent pre-processor  254 . The game controller&#39;s command signals  256  are first fed to the intelligent pre-processor  254 , which sends the modified command signals  258  to the video game console  260 .  
         [0078]     The battery  224  supplies the power  262  necessary to operate the game console  260 , the power  264  to operate the game controller  248 , and the power  266  to operate the pre-processor  254 . To ensure uninterrupted operation or immediate start of the game, either a back-up battery or ac power can be used. The recording/printing device  268  connected to the signal conditioner  222  is used to provide incentives to the players, e.g., storing the generated power levels in a data logger or printing out tokens corresponding to the power generated.  
         [0079]     The emulation of the basic video game system in the above manner is most suited for games such as racing. It can also be combined with other types of games (e.g., fights or battles) by combination with passive (e.g., springs or dampers) and active (e.g., actuators with variable impedance elements) mechanical devices (not shown here for simplicity).  
         [0080]     Although the invention has been described with particular reference to certain preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of the following claims.