Difference between revisions of "Electronic Throttle Control"
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Electric cars, by necessity, use ETC. The concept is the same but there are various small differences in the rule book that are worth looking over. | Electric cars, by necessity, use ETC. The concept is the same but there are various small differences in the rule book that are worth looking over. | ||
| − | =System Design= | + | ==System Design== |
| − | ==Sensors== | + | ===Sensors=== |
| − | ===Accelerator Pedal Position Sensors (APPS)=== | + | ====Accelerator Pedal Position Sensors (APPS)==== |
An ETC system needs a way to electronically sense the position of the throttle pedal. This is done with the APPSs, which are usually [[Rotary Position Sensor | rotary position sensors]]. For reliability, FSAE<ref>Formula SAE Rules 2023 V2.0, T.4.2.</ref> and FSG<ref>Formula Student Rules 2023, T 11.8.</ref> both require that two APPSs are used. | An ETC system needs a way to electronically sense the position of the throttle pedal. This is done with the APPSs, which are usually [[Rotary Position Sensor | rotary position sensors]]. For reliability, FSAE<ref>Formula SAE Rules 2023 V2.0, T.4.2.</ref> and FSG<ref>Formula Student Rules 2023, T 11.8.</ref> both require that two APPSs are used. | ||
| − | ===Throttle Position Sensors (TPS)=== | + | ====Throttle Position Sensors (TPS)==== |
| − | These sensors are often confused with the APPSs. The difference is that while the APPSs measure throttle pedal position, the TPSs measure the throttle position. They are usually [[Rotary Position Sensor|rotary position sensors]]. | + | These sensors are often confused with the APPSs. The difference is that while the APPSs measure throttle pedal position, the TPSs measure the throttle position at the throttle body. They are usually [[Rotary Position Sensor|rotary position sensors]]. |
| − | ===Brake System Encoder (BSE)=== | + | ====Brake System Encoder (BSE)==== |
If the driver is pressing both the throttle and the brake simultaneously for a significant amount of time, the throttle pedal might be stuck open. For this reason, the system must monitor the braking system and make sure that the throttle closes in the event of an accelerator pedal failure. The system measures this with the BSE, which is often either a brake fluid pressure sensor or a brake pedal travel sensor. | If the driver is pressing both the throttle and the brake simultaneously for a significant amount of time, the throttle pedal might be stuck open. For this reason, the system must monitor the braking system and make sure that the throttle closes in the event of an accelerator pedal failure. The system measures this with the BSE, which is often either a brake fluid pressure sensor or a brake pedal travel sensor. | ||
Note that the term BSE does not appear in the Formula Student Germany rules. | Note that the term BSE does not appear in the Formula Student Germany rules. | ||
| − | ==Safety Features== | + | ===Safety Features=== |
| − | ===Sensor Plausibility Checks=== | + | ====Sensor Plausibility Checks==== |
| − | If the TPSs don't agree with each other, or the APPSs don't agree with each other, or any of these sensors are outputting a value outside of the normal operating range, the rules require that the car must stop.<ref>Formula SAE Rules 2023, T.4.2, T.4.3, IC.4.7.</ref><ref>Formula Student Rules 2023, T 11.8., CV 1.6.6</ref> | + | If the TPSs don't agree with each other, or the APPSs don't agree with each other, or any of these sensors are outputting a value outside of the normal operating range, the rules require that the car must stop.<ref>Formula SAE Rules 2023 V2.0, T.4.2, T.4.3, IC.4.7.</ref><ref>Formula Student Rules 2023, T 11.8., CV 1.6.6</ref> |
| − | ===Brake System Plausibility Device (BSPD)=== | + | ====Brake System Plausibility Device (BSPD)==== |
| − | If the sensors report that the driver is pressing both the throttle and the brake simultaneously for a significant amount of time, the throttle pedal could be stuck open. For this reason, the system must monitor the throttle and the braking system, and make sure that the throttle closes in the event of an accelerator pedal failure. This is done with the BSPD, a standalone circuit that monitors the TPS and BSE signals and shuts the throttle if there's an implausibility.<ref>Formula SAE Rules 2023, IC.4.8.</ref><ref>Formula Student Rules 2023, T 11.6.</ref> | + | If the sensors report that the driver is pressing both the throttle and the brake simultaneously for a significant amount of time, the throttle pedal could be stuck open. For this reason, the system must monitor the throttle and the braking system, and make sure that the throttle closes in the event of an accelerator pedal failure. This is done with the BSPD, a standalone circuit that monitors the TPS and BSE signals and shuts the throttle if there's an implausibility.<ref>Formula SAE Rules 2023 V2.0, IC.4.8.</ref><ref>Formula Student Rules 2023, T 11.6.</ref> |
| − | ==Throttle Actuation== | + | ===Throttle Actuation=== |
Many teams use the 32mm [https://www.bosch-motorsport.com/content/downloads/Raceparts/Resources/pdf/Data%20Sheet_68749835_Electronic_Throttle_Body.pdf Bosch throttle body.] | Many teams use the 32mm [https://www.bosch-motorsport.com/content/downloads/Raceparts/Resources/pdf/Data%20Sheet_68749835_Electronic_Throttle_Body.pdf Bosch throttle body.] | ||
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===Control Strategies=== | ===Control Strategies=== | ||
PID or whatever else y'all goons use | PID or whatever else y'all goons use | ||
| − | == | + | ==Benefits== |
| − | |||
| − | |||
| − | |||
| − | = | ||
===Throttle cut on upshift=== | ===Throttle cut on upshift=== | ||
By putting a limit switch on the shift lever, you can easily detect when an upshift is about to occur and blip the throttle so the driver doesn't have to. If implemented properly this system can be quite reliable and shorten upshift times. | By putting a limit switch on the shift lever, you can easily detect when an upshift is about to occur and blip the throttle so the driver doesn't have to. If implemented properly this system can be quite reliable and shorten upshift times. | ||
| Line 36: | Line 32: | ||
===Programmable throttle maps=== | ===Programmable throttle maps=== | ||
Many ECUs allow you to switch out the throttle map with a push of a button. This allows you to have multiple throttle maps for different conditions: different drivers, different events, different weather, etc. | Many ECUs allow you to switch out the throttle map with a push of a button. This allows you to have multiple throttle maps for different conditions: different drivers, different events, different weather, etc. | ||
| − | + | ==Drawbacks== | |
| − | =Drawbacks= | ||
* reliability | * reliability | ||
* cost | * cost | ||
Latest revision as of 20:37, 21 January 2023
An internal combustion car with Electronic Throttle Control (or ETC) has a throttle that is controlled not by a mechanical linkage to the throttle pedal, but through an electric motor. The throttle pedal has a rotary sensor, which sends a signal to an electronically actuated throttle body. ETC systems are more complex than a mechanical throttle, but they offer extra tuning capabilities. The most common extra features are throttle cut on upshift, launch control, and traction control.
Electric cars, by necessity, use ETC. The concept is the same but there are various small differences in the rule book that are worth looking over.
Contents
System Design
Sensors
Accelerator Pedal Position Sensors (APPS)
An ETC system needs a way to electronically sense the position of the throttle pedal. This is done with the APPSs, which are usually rotary position sensors. For reliability, FSAE[1] and FSG[2] both require that two APPSs are used.
Throttle Position Sensors (TPS)
These sensors are often confused with the APPSs. The difference is that while the APPSs measure throttle pedal position, the TPSs measure the throttle position at the throttle body. They are usually rotary position sensors.
Brake System Encoder (BSE)
If the driver is pressing both the throttle and the brake simultaneously for a significant amount of time, the throttle pedal might be stuck open. For this reason, the system must monitor the braking system and make sure that the throttle closes in the event of an accelerator pedal failure. The system measures this with the BSE, which is often either a brake fluid pressure sensor or a brake pedal travel sensor.
Note that the term BSE does not appear in the Formula Student Germany rules.
Safety Features
Sensor Plausibility Checks
If the TPSs don't agree with each other, or the APPSs don't agree with each other, or any of these sensors are outputting a value outside of the normal operating range, the rules require that the car must stop.[3][4]
Brake System Plausibility Device (BSPD)
If the sensors report that the driver is pressing both the throttle and the brake simultaneously for a significant amount of time, the throttle pedal could be stuck open. For this reason, the system must monitor the throttle and the braking system, and make sure that the throttle closes in the event of an accelerator pedal failure. This is done with the BSPD, a standalone circuit that monitors the TPS and BSE signals and shuts the throttle if there's an implausibility.[5][6]
Throttle Actuation
Many teams use the 32mm Bosch throttle body.
If anyone has other systems they know about, or info on DIY systems, this section could be expanded.
Control Strategies
PID or whatever else y'all goons use
Benefits
Throttle cut on upshift
By putting a limit switch on the shift lever, you can easily detect when an upshift is about to occur and blip the throttle so the driver doesn't have to. If implemented properly this system can be quite reliable and shorten upshift times.
Throttle blip on downshift
Similarly, you can automatically blip the throttle when the driver is downshifting to shorten downshift times.
Traction control
If you have wheel speed sensors, you can implement traction control by limiting throttle when the wheels are slipping. This requires the wheel speed sensors to be both accurate and precise.
Programmable throttle maps
Many ECUs allow you to switch out the throttle map with a push of a button. This allows you to have multiple throttle maps for different conditions: different drivers, different events, different weather, etc.
Drawbacks
- reliability
- cost
- throttle body
- sensors
- computation (needs an ECM that can handle or separate module)
- complexity
