Coasting in WLTP Bosch proposal Invented for life WLTP-08-32e_annex comfortable safe clean and efficient Invented for life Coasting in WLTP Bosch proposal WLTP-Coasting Task Force, 6.11.2014 Dr. Ansgar Christ Gasoline Systems, Advanced & System Engineering Customer Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights. 1

Agenda Coasting in WLTP/Bosch Proposal General outline of BOSCH proposal BOSCH Algorithm Calculation Sequence: Step-by-Step Post-Calculation & Corrections Sensitivity on Coasting Time Share Coasting Share Definition of Coastig Time Share & BOSCH real world results Operating Strategy Coasting impact on pollutant Emissions Time resolved fuel consumption State-of-the-art Proposal & Correction method Proof of Technology & Op. Strategy while TA Next Steps & Work Packages Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Methodology to determine Coasting Benefit Coasting in WLTP/Bosch Proposal Methodology to determine Coasting Benefit General outline of BOSCH proposal: Coasting is applied “virtually” in phases with low engine power demands Using same measurement of the vehicle on dyno according to WLTP type approval testing conditions Time resolved recording of fuel consumption necessary Identify periods with low power demands using a power threshold & mark these phases as Coasting periods. e.g. choose the power threshold so that Coasting time share matches real life. Subtract fuel consumption* for identified Coasting periods from the original fuel consumption Aus Vortrag rausgenommen, um nicht unnötig zu verwirren Two corrections necessary: for engine restarts & balanced power net load * Coasting w/ engine idling consumption at idle / Coasting w/ engine off  zero Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Coasting in WLTP/Bosch Proposal based on vehicle speed: calculate power needed for vehicle movement Acceleration Pacc = m a v Friction Pfric = v * Ffric Pdrv = Pacc + Pfric Potential coasting events Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Calculation Sequence Coasting in WLTP/Bosch Proposal INPUT ALGORITHM OUTPUT Measurement data vehicle parameter: mass, friction, … vehicle speed fuel consumption (mass flow) Pre-Calculation vehicle driving power acceleration Limitations vmin, vmax amin, amax Restrict data points Vehicle speed in range Acceleration in range Determine Coasting Phases Identify data points i w/ vehicle power demand < power threshold calculate coasting time (sum of data points) preset Pthreshold coasting time share tcoast time share reached? NO: increase power threshold Post-Calculation Replace fuel consumption of data points i w/ coasting w/ engine on  idle consumption coasting w/ engine off  zero consumption idle consumption mfidle coasting benefit S replaced fuel consumptions Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Calculation Sequence: Post-Calculation Coasting in WLTP/Bosch Proposal Calculation Sequence: Post-Calculation Replacement of measured fuel mass flow mfi Coasting w/ engine on  idle consumption mfidle Coasting w/ engine off  zero consumption Idle Coasting (IDC) capable vehicle For all “Coasting data points i”: mfi is replaced with mfidle Overall Coasting Benefit: S (mfi – mfidle) Start/Stop Coasting (SSC) capable vehicle Coasting events w/ engine on and engine off occur depending on implemented strategy (e.g. time delay before switching engine off) Distribution S (tEng On)  S (tEng Off) necessary input data, e.g. 0.1  0.9 based on BOSCH measurements Overall Coasting Benefit: S (mfi – mfSSC); mfSSC = mfidle * S (tEng On) / S (tcoast) Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Calculation Sequence: Post-Calculation Coasting in WLTP/Bosch Proposal Calculation Sequence: Post-Calculation Additional Corrections Battery State-of-Charge (SOC) IDC alternator load in idle fuel consumption to be taken into account SSC compensation of battery discharge during SSC periods Proposed Method: use average powernet load and efficiencies of alternator and storage  electric energy use average efficiency of combustion engine (Willans approach)  fuel mass values to be supplied for type approval authority subtract additional fuel from (uncorrected) coasting benefit Engine start and acceleration to target speed IDC, SSC fuel mass necessary for engine acceleration from idle to gearbox input speed SSC fuel mass necessary for engine start use average number of coasting events per km (i.e. acceleration and reconnecting of engine) use additional fuel mass per coasting event Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Coasting in WLTP/Bosch Proposal Pthreshold = 2 kW Pthreshold = 6 kW 15% coasting time share 22% coasting time share IDC: 3.6 g/km (2.4%) SSC: 9.4 g/km (6.3%) IDC: 9.6 g/km (6.4%) SSC: 18 g/km (12.1%) Reference: WLTC measurement on test bench, Audi A3 1.4L TSI, MT6 Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Operating Strategy Coasting in WLTP/Bosch Proposal BOSCH Operation Strategy as implemented in Bosch democars w/ Manual Transmission. No usage of predictive data (e.g. navigation, ACC, traffic, …). Coasting if conditions are fulfilled & as soon as driver releases gas pedal & no other pedal is pressed Operating Concept gas=0 brake=0 clutch=0 open powertrain engine off or idle gas start/accelerate engine close powertrain brake (overrun  fuel cut off / recu) clutch clutch follows driver‘s intend Coasting conditions 20 km/h < v_vehicle < ~140 km/h 1000 rpm < n_engine < 3500 rpm gear ≥2 = Coasting w/ eng. idling gear ≥3 = Coasting w/ eng. off & t=1s 50 100 150 200 250 v_vehicle 1000 2000 3000 4000 5000 n_engine >0 >0 >0 Operating Strategy can have influence on Coasting Share Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Coasting Share  CO2 Benefit in WLTC Coasting in WLTP/Bosch Proposal Coasting Share  CO2 Benefit in WLTC BOSCH Proposal: Variation of coasting time share variation of power threshold and resulting fuel benefit 10 kW 6 kW 4 kW 3 kW 2 kW 1 kW Pthreshold=0.1 kW A3_WLTC.xlsx: '2012_10_16_A3_Yoshi_WLTC_SiG_Ref_01.mat‘ mf_idle = 0.18 g/s, 200W powernet Reference: Data WLTC measurement on test bench, Audi A3 1.4L TSI, MT6 Time resolved fuel consumption measured by test bench equipment (sample rate1 Hz) Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Coasting Share Coasting in WLTP/Bosch Proposal engine speed engine off CoM SSC Definition of “Coasting Time/Distance Share” = phases with powertrain open incl. Change-of-Mind cases Based on total cycle duration with vehicle speed ≥0km/h for “Coasting Time Share” (CTS) or total driven distance of cycle for “Coasting Distance Share” (CDS) BOSCH conducted measurements to analyse Coasting CO2-benefit & share for some real world test cycles & for different vehicles Focus on compact class (Audi A3 1.4L DI t/c, 90W, 6-speed MT & Citroen C4, 1.5L TDI, 90kW, 5-speed MT) & lower middle class vehicles (VW Passat 1.4L DI t/c, 90kW, 7-speed DCT) “FKFS cycle”, representing statistical vehicle usage in Germany (EU), BOSCH internal “Farmingtion Hills Cycle” for USA Proband-studies & instructed professional drivers engine start re-fire limit =0 Coasting indicated powertrain open Coasting Phase Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

FKFS real world driving route Coasting in WLTC/Bosch Proposal FKFS real world driving route publication, 2011 [1]: annual mileage in Germany for passenger cars routing city out-of-city highway FKFS road share altitude profile Typical German “commuter cycle” worked out w/ University Stuttgart for real-life CO2-benefit analyses with probands duration: 73min, length: 61km In use at BOSCH since 2002 elevation above sea level [m] Distance [km] 260 m Gasoline Systems [1] P. Rumbolz: “Untersuchung der Fahrereinflüsse auf den Energieverbrauch und die Potentiale von verbrauchsreduzierenden Verzögerungsassistenzfunktionen beim PkW”“, Dissertation, Universität Stuttgart, 2013 Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Comparison: BOSCH real world vs. official cycle Coasting in WLTC/Bosch Proposal Comparison: BOSCH real world vs. official cycle Characteristic parameters & speed distribution of NEDC, WLTC and FKFS sources NEDC WLTC V5.3 FKFS Literature [1] [2] [3] BOSCH measurements* Distance km 11.02 23.26 61.3 Duration s 1180 1800 4325 Duration stop phase % 24,8 13.4 10.8 max. speed km/h 120 131.3 124.24 average speed w/o stops 44.6 53.8 57.2 average speed w/ stops 33.6 46.5 51 max. average acceleration m/s² 1.05 1.67 3.83 max. average deceleration -1.39 -1.5 -4.09 average acceleration 0.59 0.41 0.42 average deceleration -0.79 -0.44 -0.41 Relative positive acceleration (RPA) kWs/ (kg*km) 0.1114 0.1524 0.155 * Audi A3 1.4L DI t/c 4cyl, 90W, 6-speed MT, average values for 16 probands, normal Coasting [1] G. Brunetti, L. Disarò, M. Cisternino (General Motors Powertrain), R. Fuso, F. Millo (Politecnico di Torino): “Development of a Stop & Start Sailing Activation Strategy for a Real-World Driving”, 23rd Aachen Colloquium Automobile and Engine Technology, 2014 [3] H. Stevens: “Homologation test cycles worldwide, Status of the WLTP”, Green Global NCAP labelling / green scoring Workshop 30.04.2013, international Energy Agency (iea) [3] T.Barlow, S. Latham, I. McCrae, P. Boulter: “A reference book of driving cycles for use in the measurement of road vehicle emissions”, Version 3, Published Project Report PPR354, Department for Transport, UK, 2009 FKFS cycle characteristics comparable to WLTC Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Real world tests Coasting in WLTC/Bosch Proposal campaign vehicle route driver(s) instructions 2010 “CO2 challenge” Max Coasting Benefit Audi A4, 2.0l TFSI, MT FKFS 28 drivers (“Coasting CO2- Challenge”, GS/NEstaff) w & w/o Coasting “Challenge” max. eco 2011 Coasting Share & Benefit of Average driver (probands). UX –Study. VW Passat, 1.4l TSI, 7-speed DCT 23 drivers (randomly selected, GS staff) 11 test drivers for CO2 w/ calculated St/St base, 11+12 test drivers for Coast share only without instructions “driving as usual” Coasting Benefit of “normal” & “max eco” driving style (professional driver ) professional driver different driving premises (4-5 cycles each) Base: normal w/o Coasting normal driving w/ Coasting eco driving w/ Coasting 2012/13 Realistic Coasting Share & Benefit of Average driver (probands). Reference for eCS components. UX-Study. Audi A3, MT w/ eCS 25/16 test drivers (selected BOSCH staff. good mixture of age, gender, profession) 2013 OEM Test of different driving styles. IDC vs. SSC (professional driver) OEM “real-life cycle” (Paris) 3 different driving premises 1 cycle base + 1 cycle Coasting each normal w/ & w/o Coasting dynamic w/ & w/o Coasting eco w/ & w/o Coasting Coasting in US Farmington Hills Route 20 drivers 7 drivers (out of above 20) Instructed 2014 “Lastkollektiv” & FKFS vs. LCM Comparison of different driving styles, variation of OP Strategy. Gasoline & diesel vehicle GS: Audi A3, DS: Citroen C4 1.6l TDI, (ETC)LCM Selected drivers & professional drivers (DS staff) 3 different driving premises, 3 different operating strategies for C4 mostly only 1 cycle per variation 29 drives normal w/ Coasting dynamic w/ Coasting eco w/ Coasting Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Coasting Share: Representative average base value Coasting in WLTP/Bosch Proposal Coasting Share: Representative average base value Average Coasting Time Share found: 25%* (=30% Coasting Distance Share) 17%...35% (FKFS, A3, probands, normal driving) & 30…36% (FKFS, Passat, professional driver, normal driving), Average 22%** for Farmington Hill cycle (11%...56%) JRC Monograph: Porsche field data indicate 26% CTS Representative average base value for most vehicles & drivers Coasting time shares are based on driver statics and are used for the calculation of the CO2 benefit of coating technology Each Contracting Party may develop its own coasting time share(s) based on regional data . 25% CTS assumed to be representative base (for BOSCH strategy) Operating strategy has to be considered in algorithm * Base: BOSCH Operating Strategy, based on total cycle time/distance with powertrain open until engine re-start @vehicle speed ≥0km/h ** VW Passat with DCT Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Coasting impact on pollutant Emissions Coasting in WLTP/Bosch Proposal Coasting impact on pollutant Emissions For coasting systems the situation is similar as for current Start/Stop systems We assume that coasting will only be enabled if the exhaust after-treatment system has reached its operating conditions, e.g. warmed up TWC For IDC during coasting the engine emits idle emissions as during normal idle phases no engine restart necessary For SSC (similar as for Start/Stop systems) during coasting the ICE is switched off, without emissions engine restart necessary, but due to the short duration of coasting phases (mostly between X and 10 seconds) no air flow through stopped engine (very little cooling of engine and aftertreatment system) (different to fuel cut-off air with air flow) no or only a very small effect on emissions after an ICE-off-phase is expected Our base vehicle features Start/Stop and we did not determine relevant emission differences between Start/Stop and non-Start/Stop operation Emissions could be measured during the proposed coasting verification test Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Coasting impact on pollutant Emissions Coasting in WLTP/Bosch Proposal Coasting impact on pollutant Emissions Measurements conducted on dyno, Bosch Schwieberdingen in 2012 FTP75 (Vehicles with EU calibration!) or NEDC Start/Stop (base), (IDC), SSC Coasting with „OptiCoast“ (using tolerance band to generate speed curve with coasting phases) Vehicles Passat 1.4 TSI, Audi A3 1.4 TSI CLS 3.5L DI, gasoline Audi A3 2.0 TDI Measured HC, NOx, CO, (PM), (CO2), (NMHC) 1 … 3 test(s) per configuration Result: No obvious/significant change of emission due to Coasting Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Time resolved fuel consumption Coasting in WLTP/Bosch Proposal Time resolved fuel consumption BOSCH proposal needs a method to measure time resolved fuel consumption Overview of possible ways to determine actual fuel consumption of vehicles: direct measurements of fuel flow ? correlation with exhaust gas measurement  model of fuel injection (injection time, flow characteristic, …)  External exhaust gas measurement and calculating with model is state-of-the-art Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Time resolved fuel consumption Coasting in WLTP/Bosch Proposal Time resolved fuel consumption State-of-the-art exhaust gas methods ECE R83: cumulative exhaust gas analyses (“bag”) using a full-flow exhaust dilution system (Constant Volume Sampler), accuracy +/-2% Continuous time resolved (“modal”) exhaust gas sampling Usage simultaneously with type approval “bag”-measurements is not regulated. BOSCH analyses: same accuracy as “bag”-method further improvements to be checked (internal study on-going) sampling frequency about 1Hz, tail-pipe measure delay between actual consumption and engine operating point to be considered Portable Emission Measurement Systems (PEMS) HDV-regulation (EC) 595/2009, RDE for LDV under development Industry standard available? DIN, VDA, SAE? OBD On-board diagnostics PID Parameter IDs HDV Heavy Duty Vehicle CAN (Controller Area Network) LDV Light Duty Vehicle RDE Real Driving Emissions Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Time resolved fuel consumption Coasting in WLTP/Bosch Proposal Time resolved fuel consumption State-of-the-art ECU based methods Engine control unit (ECU) calculates consumption based on injection model frequency: 100ms, no delay between actual consumption and engine operating point Available on CAN bus in most vehicles, not standardized SAEJ1979DA: some consumption related values (PIDs) available via OBD-Interface for some diesel vehicles (esp. HD) mandatory, e.g. PID$5E Engine Fuel Rate 0.05 L/h per bit, PID$9D Engine Fuel Rate 0.02 g/s per bit, PID$A2 Cylinder Fuel Rate 0.03125 mg/stoke per bit OBD bus rate can vary depending on traffic but always <1Hz Analyses show no significant effect for <=1Hz! Also considered for EU RDE PEMS LDV purposes OBD On-board diagnostics PID Parameter IDs HD Heavy Duty CAN (Controller Area Network) Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Time resolved fuel consumption: Proposal Coasting in WLTP/Bosch Proposal Time resolved fuel consumption: Proposal Correction method for modal or OBD time resolved data ”bag” While type approval measurement: additional continuous exhaust gas sampling or time resolved calculated fuel consumption via OBD Verify by comparing cumulated time resolved value with bag & correct time resolved data if necessary Standard Type approval measurement Correction factor c = x / y fuel_flow_corr (t) = c * fuel_flow_original (t) bag: x Liter Additional data time res.: y Liter OR OBD Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Proof of Technology & Op. Strategy while TA Coasting in WLTP/Bosch Proposal Proof of Technology & Op. Strategy while TA BOSCH application so far only (post-)processes TA measurements ”…no proof in TA of actual technology or OEM operating strategy!…” Proposal: additional simple test procedure, conducted after std. TA measurements (not used to determine CO2-Benefit!) OEM has to declare his implemented Coasting strategy in advance Relevant parameters: entry and exit speed limits, IDC vs. SSC speed limits, delay time(s) completeness to be checked Vehicle driving short test on dyno (e.g. 5 min, vehicle warm) consisting of different constant speed levels & following coast down to a minimum speed (e.g. 15km/h). Indication to test driver of act. speed, act. gear (MT) & when to release gaspedal measured parameters t.b.d. proposal: vehicle speed, engine speed and/or time resolved fuel flow (SSC/IDC), PT open/closed condition (OBD-Interface SAE!)* Output of test: Proof of technology / operating strategy according OEM statement. speed time *Roll-out curves on dyno or street (transmission in N) for standard TA are available distinction between Coasting and overrun possible? Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Proof of Technology & Op. Strategy while TA Coasting in WLTP/Bosch Proposal Proof of Technology & Op. Strategy while TA Example: Start/Stop Coasting with 1sec until transmission open & 4 sec delay for engine off “release gaspedal!” “end coast phase!” gas pedal gear vehicle speed const. speed t_const t_min_const min. time until next acceleration const. accel. Coasting down, until v_exit or v_min reached v_const_x t_delay_PT until transmission open t_delay_idle until engine speed =idle t_idle  engine speed =idle t_eotime engine off a (v_exit_x) e.g. operating strategy with v_exit > v_min v_min time engine speed open PT Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Next Steps / Work Packages Coasting in WLTP/Bosch Proposal Next Steps / Work Packages WP “Time resolved fuel consumption” WP “Proof of Technology & Op. Strategy” Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

WP “Time resolved fuel consumption” Coasting in WLTP/Bosch Proposal WP “Time resolved fuel consumption” Decision on most promising procedure Formulate regulation for modal exhaust gas measurement & discuss with SAEJ1979 working group to set necessary PIDs to “mandatory” or “optional for Coasting vehicles” OR formulate regulation for modal exhaust gas measurement Decision/commitment of WLTP-TP members for further procedure necessary Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

WP “Proof of Technology & Op. Strategy” Coasting in WLTP/Bosch Proposal WP “Proof of Technology & Op. Strategy” Work out suitable speed profile Define measured variables Formulate regulation for “PT_open” & discuss with SAEJ1979 working group to set necessary PIDs to “mandatory” or “optional for Coasting vehicles” Decision/commitment of WLTP-TP members for further procedure necessary Gasoline Systems Confidential | GS/ESC | 06/11/2014 | © Robert Bosch GmbH 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.