Electronics Guide

Tire Pressure Monitoring Systems

Tire pressure monitoring represents one of the most successful commercial applications of energy harvesting in transportation. TPMS sensors mounted inside tires face significant challenges for battery replacement, making energy harvesting an attractive alternative. Motion-powered sensors harvest energy from tire rotation and road vibration to monitor pressure continuously throughout tire life.

Piezoelectric harvesters capture energy from tire deformation during rolling contact. The cyclical flexing of the tire sidewall provides consistent mechanical energy at frequencies determined by vehicle speed. Electromagnetic generators using rotating masses produce power from centrifugal effects during wheel rotation. Hybrid designs combining multiple harvesting mechanisms ensure adequate power across varying driving conditions.

Energy harvesting TPMS sensors last the lifetime of the tire, eliminating the need to replace batteries when changing tires. The reliability improvement is particularly valuable for commercial fleet vehicles where tire-related breakdowns cause expensive delays. As regulatory mandates expand TPMS requirements globally, energy harvesting solutions gain market share.

Wheel and Hub Monitoring

Beyond tire pressure, wheel assemblies benefit from monitoring of bearing temperature, vibration, and load conditions. Energy harvesting sensors on wheel hubs and brake assemblies detect developing problems before they cause failures. Thermoelectric generators harvest heat from brakes and bearings, while vibration harvesters capture mechanical energy from rotating components.

Bearing temperature monitoring provides early warning of lubrication failure and wear. Vibration analysis detects bearing defects and wheel imbalance. Load sensors monitor weight distribution for vehicle stability and cargo management. The comprehensive monitoring enabled by energy harvesting improves vehicle safety and reduces maintenance costs.

Engine and Powertrain Monitoring

Engine compartment sensors monitor temperature, pressure, vibration, and fluid conditions throughout the powertrain. Energy harvesting from engine vibration and waste heat powers sensors in locations difficult to wire. Thermoelectric generators on exhaust manifolds and engine blocks harvest substantial power from high temperature surfaces.

Oil condition monitoring detects contamination and degradation indicating maintenance needs. Coolant sensors track temperature and level for overheating prevention. Exhaust gas sensors support emissions control and engine optimization. The harsh thermal environment of engine compartments challenges sensor electronics but provides abundant harvesting energy.

Vehicle Body Sensors

Collision detection, occupant sensing, and body condition monitoring benefit from distributed sensors throughout vehicle structures. Energy harvesting enables sensor placement without wiring through body panels and structural members. Solar cells integrated into roof panels and glass harvest light for vehicle body sensors and auxiliary systems.

Structural Health Monitoring

Aircraft structural integrity monitoring is critical for flight safety. Energy harvesting sensors distributed throughout airframes detect fatigue cracks, corrosion, and impact damage. The weight savings from eliminating sensor wiring is particularly valuable in aircraft where every gram affects fuel consumption. Vibration from engines and airflow provides abundant mechanical energy for harvesting.

Strain gauges monitor stress in critical structural locations. Acoustic emission sensors detect crack formation and growth. Corrosion sensors track environmental degradation of aluminum and composite structures. The ability to add sensors without weight-adding wiring enables the dense coverage needed for comprehensive structural monitoring.

Aircraft vibration environments vary significantly between flight phases. Takeoff and landing produce high vibration levels, while cruise conditions may be relatively smooth. Energy harvesting systems must accommodate this variation through energy storage that bridges low-vibration periods. Multi-source harvesting combining vibration, thermal gradients, and solar energy improves reliability.

Engine Health Monitoring

Aircraft engine monitoring prevents in-flight failures and optimizes maintenance scheduling. Energy harvesting sensors on engine nacelles and pylons capture vibration energy from engine operation. Thermoelectric generators harvest heat from engine cases and exhaust systems. The extreme temperature gradients in engine environments provide substantial thermoelectric harvesting potential.

Vibration analysis detects bearing wear, blade damage, and compressor health. Temperature monitoring tracks hot section condition and cooling effectiveness. Oil debris monitoring identifies component wear before failure. Continuous engine health data enables condition-based maintenance reducing both failures and unnecessary scheduled maintenance.

Cargo and Cabin Monitoring

Cabin environmental monitoring affects passenger comfort and safety. Energy harvesting sensors track temperature, humidity, and air quality throughout passenger compartments. Cargo hold monitoring detects fire, smoke, and hazardous atmosphere conditions. Solar cells harvest cabin lighting while piezoelectric floor sensors detect passenger presence and movement.

Landing Gear Monitoring

Landing gear systems experience severe stress during takeoff and landing. Energy harvesting sensors monitor strut pressure, brake temperature, and structural condition. Shock absorption during landing provides significant mechanical energy for harvesting. Weight-on-wheels sensing enables automatic system configuration for ground and flight operations.

Track Condition Monitoring

Railroad track condition affects safety, ride quality, and maintenance requirements. Energy harvesting sensors along track monitor rail stress, geometry, and joint condition. Solar panels along right-of-way and vibration harvesters powered by passing trains provide distributed energy throughout rail networks.

Rail temperature monitoring prevents heat-related buckling in summer and cold-related fractures in winter. Rail stress sensors detect loads exceeding safe limits from overweight cars. Track geometry sensors measure gauge, alignment, and surface affecting ride quality. Joint sensors detect loosening fasteners and deteriorating rail ends.

The intermittent nature of train passage creates challenges for vibration harvesting. Energy storage systems must accumulate energy during train passages for continuous monitoring between trains. Supercapacitors provide rapid charge acceptance and long cycle life suited to this pulsed energy availability pattern.

Rolling Stock Monitoring

Railroad cars and locomotives contain numerous systems requiring monitoring for safety and maintenance. Energy harvesting sensors on wheel sets, suspensions, and car bodies track condition throughout the rail network. Vibration from rail travel provides abundant mechanical energy, while temperature differences between wheel and ambient air enable thermoelectric harvesting.

Wheel flat detection identifies damaged wheels causing track damage and ride quality problems. Bearing monitors detect overheating indicating imminent failure. Draft gear sensors monitor coupling forces and alignment. Load sensors ensure weight limits are respected and cargo is properly distributed.

Wayside Detection Systems

Trackside detectors identify problems with passing trains including hot bearings, dragging equipment, and shifted loads. Solar-powered detection systems operate at remote locations without power infrastructure. Autonomous monitoring stations inspect every passing train without operator presence.

Signal and Communication Systems

Rail signal and communication infrastructure spans thousands of miles of track. Solar-powered signal monitoring and repeater stations reduce infrastructure costs in remote areas. Energy harvesting sensors on signal equipment detect failures and degradation before affecting train operations.

Hull Structural Monitoring

Ship hulls experience continuous stress from wave loading, cargo forces, and temperature variations. Energy harvesting sensors distributed throughout hull structures monitor strain, fatigue, and corrosion. Wave motion provides mechanical energy, while ocean temperature gradients enable thermoelectric harvesting. Solar panels on deck structures supplement other energy sources.

Hull stress monitoring prevents structural failures in heavy weather. Fatigue tracking in critical locations enables condition-based surveys. Corrosion monitoring tracks protective coating degradation and steel thickness loss. Watertight integrity sensors detect flooding before it becomes critical.

Propulsion System Monitoring

Marine propulsion systems including engines, shafts, and propellers require continuous monitoring. Energy harvesting sensors capture vibration from machinery operation and heat from engine exhaust. Condition monitoring enables predictive maintenance that prevents breakdowns far from port.

Shaft vibration analysis detects alignment problems and bearing wear. Propeller monitoring tracks blade condition and cavitation damage. Engine monitoring covers lubrication, cooling, and combustion parameters. The integration of harvested energy with monitoring functions creates autonomous diagnostic systems.

Cargo Monitoring

Container and bulk cargo monitoring tracks condition, temperature, and security throughout voyages. Energy harvesting cargo sensors operate independently throughout multi-week ocean crossings. Solar panels on container tops, thermoelectric generators using cargo temperature differentials, and kinetic harvesters capturing ship motion power cargo monitoring systems.

Temperature monitoring protects perishable and temperature-sensitive cargo. Shock and vibration recording documents handling conditions for damage claims. Security sensors detect unauthorized container access. Location tracking through the supply chain provides visibility for shippers and receivers.

Navigation Aid Monitoring

Buoys, beacons, and other navigation aids mark channels and hazards throughout waterways. Solar-powered navigation aids have operated reliably for decades. Energy harvesting enables additional sensing functions including environmental monitoring, vessel tracking, and aid-to-navigation system health monitoring.

Truck and Trailer Monitoring

Commercial trucking benefits from comprehensive monitoring of tractors, trailers, and cargo. Energy harvesting enables monitoring of trailer systems disconnected from tractor power. Solar panels on trailer roofs and refrigeration units harvest abundant energy, while vibration harvesters capture energy from road travel.

Refrigerated trailer temperature monitoring ensures cold chain integrity. Tire and brake monitoring improves safety and reduces roadside breakdowns. Cargo sensors track loading, weight distribution, and security. Door sensors document cargo access for chain of custody verification.

Bus and Transit Vehicle Monitoring

Public transit vehicles require monitoring of passenger systems, safety equipment, and vehicle condition. Energy harvesting sensors throughout buses and rail cars operate without battery replacement by maintenance staff. Passenger counting, air quality monitoring, and emergency system verification benefit from self-powered sensors.

Fleet Management Integration

Energy harvesting sensor data integrates with fleet management systems for vehicle tracking, maintenance planning, and operational optimization. Telematics platforms aggregate sensor data with vehicle location and driver behavior. Analytics identify trends requiring attention before they cause problems.

Vibration Environment Characterization

Transportation vibration environments vary significantly by mode, location, and operating conditions. Effective harvester design requires understanding of frequency content, amplitude ranges, and temporal patterns. Vehicle testing characterizes the actual vibration environment for harvester optimization.

Resonant harvesters tuned to dominant frequencies maximize power extraction. Broadband harvesters accommodate variable-speed operation and multiple vibration sources. Frequency tuning mechanisms adapt to changing conditions. The vibration characterization effort significantly impacts harvester effectiveness.

Temperature Extremes

Transportation systems expose sensors to temperature extremes from arctic cold to engine compartment heat. Energy harvesting systems must operate reliably across the full temperature range. Battery and capacitor characteristics vary significantly with temperature, requiring appropriate selection and management.

Wide-temperature electronics maintain function from -40 to +125 degrees Celsius depending on application requirements. Thermal management protects sensitive components from extreme conditions. Temperature compensation maintains measurement accuracy across the operating range.

Shock and Vibration Survival

Transportation shock and vibration levels can damage sensitive electronics. Ruggedized packaging protects harvesting and sensing components. Shock isolation reduces transmitted forces while allowing vibration energy transfer for harvesting. Design validation through shock and vibration testing ensures survival in service.

Regulatory Compliance

Transportation systems are heavily regulated for safety. Energy harvesting sensors must meet applicable standards for electromagnetic compatibility, flammability, and hazardous materials. Automotive, aerospace, rail, and maritime regulations each impose specific requirements. Compliance documentation supports system certification and customer acceptance.

Fail-Safe Design

Safety-critical transportation systems require fail-safe design that prevents dangerous conditions if monitoring fails. Energy harvesting variability must not compromise safety function availability. Redundant energy sources and storage provide backup for critical monitoring functions.

Data Integrity

Transportation monitoring data affects safety-critical decisions. Data integrity mechanisms ensure accurate and reliable information. Error detection and correction protect against communication errors. Authenticated data prevents spoofing attacks on safety systems.

Maintenance Integration

Energy harvesting sensor data must integrate with established maintenance programs. Standard data formats enable use with existing maintenance management systems. Alarm thresholds align with maintenance action requirements. The monitoring system must support rather than complicate maintenance operations.

Autonomous Vehicle Integration

Autonomous vehicles require extensive sensing beyond current monitoring systems. Energy harvesting can power redundant sensors improving autonomous system reliability. Self-powered sensors add monitoring capability without increasing vehicle electrical system complexity.

Electric Vehicle Applications

Electric vehicles present new energy harvesting opportunities and challenges. Regenerative braking already harvests vehicle kinetic energy. Additional harvesting from suspension motion and road vibration can supplement battery charging. Battery thermal management creates temperature gradients exploitable for thermoelectric harvesting.

Urban Air Mobility

Emerging urban air mobility vehicles including electric vertical takeoff and landing aircraft will require comprehensive monitoring. Energy harvesting sensors provide weight-efficient monitoring solutions for these weight-sensitive aircraft. The unique vibration and thermal environments of electric propulsion create new harvesting opportunities.