Project
| # | Title | Team Members | TA | Documents | Sponsor |
|---|---|---|---|---|---|
| 22 | MULTI-MODE TABLE TENNIS TARGET TRAINING SYSTEM |
Alice Xu Ben Seo Brandon Dang |
Abdullah Alawad | design_document1.pdf proposal1.pdf |
|
| MULTI-MODE TABLE TENNIS TARGET TRAINING SYSTEM Team Members: Brandon Dang (bd16) Ben Seo (seo58) Alice Xu (alicex2) PROBLEM Shot placement and the ability to quickly adjust where the ball is directed are important skills in table tennis. Traditional accuracy drills often use tape, cones, or other passive markers placed on the table. These targets can show a player where to aim, but they cannot automatically determine whether the player successfully hit the intended location or record performance over repeated shots. Reaction and placement drills also commonly require a coach, partner, or ball machine operator to repeatedly tell the player where to aim. This makes it difficult for a player to independently perform randomized targeting drills and quantitatively track their accuracy. Our goal is to create an electronic table tennis training system that automatically selects target locations, visually indicates where the player should aim, detects ball impacts, and records performance. The required system will include a Rapid-Fire Placement Mode and a Serve Accuracy Mode. A Reaction Return Mode will be pursued as a stretch goal. SOLUTION The proposed system will consist of at least three low-profile electronic target pads placed on the opponent's side of a standard table tennis table and one central controller. Each target will contain a rigid low-profile impact surface, piezoelectric impact sensor, analog signal-conditioning circuit, high-brightness LEDs, ESP32 microcontroller, wireless communication, and a custom PCB. The targets will be movable so that they can be positioned at different locations on the table depending on the drill. Example locations include the left corner, center, right corner, short serve location, and deep serve location. When a target is selected, LEDs around its perimeter will illuminate. The player will attempt to bounce the ball on the selected target. The piezoelectric sensor will detect the impact and report which target was struck to the central controller. All targets will continue monitoring for impacts even when they are not illuminated. This allows the system to distinguish between a correct target hit, a wrong electronic target hit, and a shot that misses all electronic targets. The three target units will use the same PCB and firmware architecture, with each unit assigned a unique software identifier. The system will support two required training modes. RAPID-FIRE PLACEMENT MODE For Rapid-Fire Mode, the three targets will be positioned at different locations on the opponent's side of the table. A player will receive consecutive balls from a training partner, an existing ball machine, or a controlled manual feed. The electronic training system itself will not be responsible for launching the balls. One target will illuminate at a time. The player must redirect the incoming ball so that its first bounce on the opponent's side lands on the illuminated target. After the correct target is struck, another electronic target is struck, or a configurable timeout occurs, the controller will automatically select and illuminate another random target. A typical sequence would be: 1. Target 2 illuminates. 2. The player receives an incoming ball. 3. The player attempts to hit toward Target 2. 4. Target 2 detects the bounce. 5. The controller records a correct shot. 6. Target 1 immediately illuminates. 7. The drill continues with the next incoming ball. The controller will record correct target hits, wrong-target hits, misses or timeouts, overall accuracy, and consecutive-hit streaks. Target response time may also be recorded. If this feature is used, target response time will be defined as the time between target illumination and target impact. It will not be described as pure human reaction time because the measurement also includes stroke execution and ball flight. The primary performance metric for Rapid-Fire Mode will be shot-placement accuracy. SERVE ACCURACY MODE For Serve Accuracy Mode, the same electronic targets will be repositioned to represent different serve locations on the opponent's side of the table. Possible target locations include short left, short right, deep left, deep right, and center/body. At least three target locations will be used during the required demonstration. Before each serve, one target will randomly illuminate. The player will perform their normal serving motion and attempt to make the legal serve bounce on the selected electronic target on the opponent's side of the table. Serve timing will not be used as a performance metric because rewarding a faster serving motion could encourage the player to rush their normal technique. A serve will be classified as one of the following: Correct: The selected target was struck. Wrong Target: Another electronic target was struck. Miss: No electronic target was struck. If a target is hit, the result will be recorded automatically. If the serve misses all electronic targets, the player will press a Next Serve / Mark Miss button on the central controller. The previous attempt will then be recorded as a miss and another target will be selected. The controller will maintain total serves, correct target hits, wrong-target hits, misses, overall serve accuracy, and, if time permits, accuracy for each target location. SOLUTION COMPONENTS TARGET MECHANICAL AND IMPACT-SURFACE SUBSYSTEM Each target will be constructed as a low-profile impact pad approximately 10 inches by 10 inches. The final dimensions may be adjusted after prototype testing to balance target difficulty and reliable impact detection. The initial target design will use a thin rigid impact plate made from polycarbonate, thin plywood, or another lightweight material that produces a consistent table tennis ball rebound. The target will be kept below approximately 0.5 inches in total height. Each target will include: Thin rigid impact plate Piezoelectric sensor mounted beneath the plate High-friction rubber or silicone bottom surface Protected LED perimeter Small protected electronics enclosure positioned near the rear edge The high-friction bottom surface will prevent the target from moving significantly when struck. The LEDs will be positioned around the perimeter rather than in the center of the impact area so that the table tennis ball cannot directly damage them. Because placing a target on the table changes the surface the ball contacts, the target material will be selected through rebound testing. A ball will be dropped from a known height onto both the normal table surface and the target plate. The target should provide a rebound reasonably similar to the bare table so that successfully hitting the target does not completely stop normal play. The targets will be removable and repositionable so that the same three electronic modules can be used for both Rapid-Fire and Serve Accuracy Modes. IMPACT SENSING AND SIGNAL-CONDITIONING SUBSYSTEM Each target will detect table tennis ball impacts using a piezoelectric vibration sensor mounted underneath the impact plate. The proposed sensor is the PUI Audio AB2036B piezoelectric element. A table tennis ball impact produces a short mechanical vibration in the target surface. Because a table tennis ball is relatively light, the impact-sensing circuit will be designed and experimentally calibrated to detect small impact signals reliably. The raw piezoelectric output may contain positive and negative voltage transients, mechanical ringing, environmental vibration, and electrical noise. The piezoelectric signal will therefore pass through a custom analog front-end circuit before reaching the microcontroller. The circuit will include: MCP6002 dual operational amplifier Input current-limiting resistor Voltage clamping and protection circuitry RC filtering Adjustable or programmable gain Adjustable impact-detection threshold ESP32 ADC input The microcontroller will continuously monitor the conditioned sensor signal. The detection algorithm will approximately perform the following steps: 1. Sample the conditioned piezoelectric signal. 2. Reject low-amplitude background vibration. 3. Detect when the signal exceeds the calibrated threshold. 4. Identify the first impact peak. 5. Register one target hit. 6. Ignore mechanical ringing for a short lockout period. Impact thresholds will be determined experimentally using actual table tennis ball impacts at several locations across each target. If a single piezoelectric sensor does not provide reliable detection near the target edges, the mechanical design will support adding a second piezo sensor without changing the overall target architecture. TARGET ILLUMINATION AND DRIVER SUBSYSTEM Each target will contain high-brightness LEDs around the perimeter of the target surface. The LEDs will allow the player to quickly determine which target is currently active from the opposite side of the table. The LEDs will not be powered directly from the ESP32 GPIO pins. The custom PCB will include driver circuitry using an AO3400A N-channel MOSFET, current-limiting resistors, a gate resistor, a gate pull-down resistor, and an ESP32 GPIO control signal. The target will support several visual states: OFF: The target is inactive. ACTIVE: The player should aim for this target. SUCCESS: A brief visual indication after a correct impact. WRONG TARGET: An optional alternate indication when an incorrect target is hit. Different LED colors or flash patterns may be used to distinguish these states. EMBEDDED CONTROL AND WIRELESS COMMUNICATION SUBSYSTEM Each target will contain an ESP32-C3-WROOM-02 microcontroller. The microcontroller will locally control LED activation, piezoelectric signal sampling, impact detection, impact timestamping, target identification, and wireless communication. Performing impact detection locally reduces communication delays and allows each target to operate independently. Each target will continuously monitor for ball impacts regardless of whether it is currently illuminated. This allows the system to identify a wrong-target hit. For example, if Target 2 is active but the player hits Target 1, Target 1 will send an impact message to the central controller. The controller will recognize that Target 2 was active, record the shot as a wrong-target hit, and then select the next target. Each target PCB will have identical hardware. Individual targets will be assigned unique software identifiers. Communication between the targets and central controller will use ESP-NOW or another suitable peer-to-peer protocol supported by the ESP32. CENTRAL CONTROLLER AND USER-INTERFACE SUBSYSTEM A central controller will coordinate the training session. The controller will include: ESP32-C3-WROOM-02 microcontroller SSD1306 0.96-inch I2C OLED display Start/stop button Mode-selection button Next Serve / Mark Miss button Status LEDs Wireless communication with the target units The controller will support at least Rapid-Fire Placement Mode and Serve Accuracy Mode. During Rapid-Fire Mode, the display will show information such as the current trial number, number of correct hits, wrong-target hits, misses, overall accuracy, and current hit streak. If target response timing is enabled, the most recent and average target response times may also be displayed. During Serve Accuracy Mode, the display will show the selected target, total number of serves, correct hits, wrong-target hits, misses, and overall accuracy. The system will not place any timing requirement on the player's serving motion. POWER SUBSYSTEM The system will use external low-voltage power rather than custom rechargeable batteries. Because all targets are located on a table approximately 9 feet long, a single external 5 V supply may be distributed to the target units using low-voltage cables routed along or underneath the table. Each target PCB will include: 5 V power input AP2112K-3.3 voltage regulator Input and output decoupling capacitors Local bypass capacitors Power indicator Input protection The LED driver circuitry and sensitive piezoelectric analog circuitry will be physically separated on the PCB as much as practical to prevent LED switching from causing false impact detections. CRITERION FOR SUCCESS 1. Multiple Target Operation The system must independently operate at least three physical electronic targets and randomly select one target at a time. 2. Target Visibility The active target must be clearly identifiable from at least 3 meters away under normal indoor lighting. 3. Impact Detection Each target must correctly detect at least 90% of direct table tennis ball impacts during a controlled test of at least 30 impacts per target. Test impacts will include multiple locations across the target surface rather than only the center. 4. Multiple-Impact Rejection A single physical table tennis ball impact must register as no more than one hit. 5. Background Noise Rejection Normal table vibration, nearby ball bounces, and LED switching must not create more than one false impact detection during a 5-minute stationary test. 6. Target Stability During 20 representative table tennis ball impacts, each target must remain flat on the table and must not move more than 2 cm from its initial position after any individual impact. 7. Target Rebound Performance A table tennis ball will be dropped from a fixed height onto both the target plate and the bare table surface. The average rebound height from the target surface must be within 25% of the average rebound height from the bare table over at least 10 trials on each surface. This requirement ensures that the electronic target does not completely absorb the ball's energy or prevent normal play. 8. Correct/Wrong Target Identification When one target is active, the controller must correctly distinguish between an impact on the selected target and an impact on either of the other electronic targets. During a controlled test of at least 30 total target impacts, the system must classify at least 90% correctly. 9. Rapid-Fire Placement Mode The system must complete a drill containing at least 20 randomized target activations without requiring the user to manually select the target for each trial. After a target hit or timeout, the next target must automatically be selected and illuminated. The controller must record correct hits, wrong-target hits, misses or timeouts, total trials, and accuracy percentage. 10. Serve Accuracy Mode The system must complete a serve-accuracy session containing at least 10 serves and at least three selectable target locations. For each serve, the system must classify the result as a correct target hit, wrong electronic target hit, or user-confirmed miss. The system must display overall serve accuracy at the end of the session. 11. Wireless Communication Each target must successfully communicate activation and impact information with the central controller at a distance of at least 5 meters in an indoor environment. 12. Performance Recording For Rapid-Fire Mode, the central controller must display: Correct hits Wrong-target hits Misses or timeouts Total trials Accuracy Current hit streak For Serve Accuracy Mode, the central controller must display: Selected target Correct hits Wrong-target hits Misses Total serves Accuracy 13. Custom Circuit Design Each target will use a custom PCB containing: ESP32 microcontroller interface Piezoelectric impact-sensor analog front end Amplification and filtering circuitry Input protection circuitry LED driver circuitry Power-regulation circuitry At least three physical target units will operate using the same PCB architecture. 14. End-to-End Demonstration During the final demonstration, the system must demonstrate both required training modes. For Rapid-Fire Placement Mode, the system must: 1. Randomly select a target. 2. Illuminate the selected target. 3. Detect a table tennis ball impact. 4. Determine whether the correct or wrong electronic target was struck. 5. Record the result. 6. Automatically select the next target. For Serve Accuracy Mode, the system must: 1. Randomly select a serve target. 2. Illuminate the selected target. 3. Allow the player to complete a normal untimed serve. 4. Detect a correct or wrong target impact. 5. Allow the player to manually record a serve that misses all targets. 6. Update the accuracy statistics. 7. Select the next target. STRETCH GOAL: REACTION RETURN MODE After the required Rapid-Fire Placement and Serve Accuracy modes are working reliably, the system will be extended to support a Reaction Return Mode. In this mode, balls will be supplied by a training partner or existing ball machine. The target location will not be revealed until the incoming ball has been fed toward the player. A feed trigger may be implemented using an optical ball-detection sensor near the feed source, a physical trigger button operated at the moment of feed, or synchronization with an available ball machine. When an incoming ball is detected or triggered, the controller will immediately select and illuminate a random target. The player must recognize the newly selected location and redirect the incoming ball toward that target. The system will record the selected target, correct target hits, wrong-target hits, misses, and target response time. Because synchronization with the incoming ball adds additional sensing and timing requirements, Reaction Return Mode will remain a stretch goal and will not be required for successful completion of the base project. |
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