4.19. Limp Mode - LimpMod

• Overview

• Functions

• Ports

• Parameters

• Calibration

Id	LimpMod
Version	0.3.1.1
Title	Limp Mode
System	Drivetrain
Document Type	Application Software Component Specification Preview

4.19.1. Overview

The Limp Mode component determines if the vehicle should enter a limp mode with reduced speed based onrequests from various vehicle subsystems. It monitors requests and validity signals from the High Voltage Power,Braking, Drivetrain, Steering, Suspension, Door closure systems. If a valid limp mode request is received,the component will output a reduced maximum vehicle speed limit.

4.19.2. Functions

	Title	Description
1	Limp Mode Request Processing	Processes limp mode requests from various vehicle subsystems. Determines if each request is valid based on a validity signal. Outputs a flag indicating if any subsystem has made a valid limp mode request.
2	Limp Mode Speed Limit Determination	Determines the minimum speed limit value from all the subsystems that have limp mode enabled. Outputs this minimum speed as the limp mode vehicle speed limit.

4.19.3. Ports

	Id	Direction	Data Type	Dimensions	Unit	Description	Keywords
1	Ts	Incoming	single	[1]	sec		Ts
2	HvLimpModReq	Incoming	boolean	[1]	inherit	Expected signal: Hv request for limp mode If signal si NA: mandatory. False	Hv Limp Mode Request
3	BrkLimpModReq	Incoming	boolean	[1]	inherit	Expected signal: Braking request for limp mode If signal si NA: mandatory. False	Brake Limp Mode Request
4	DrvLimpModReq	Incoming	boolean	[1]	inherit	Expected signal: Driver request for limp mode If signal si NA: mandatory. False	Drive Limp Mode Request
5	SteerLimpModReq	Incoming	boolean	[1]	inherit	Expected signal: Steer system request for limp mode If signal si NA: mandatory. False	Steering Limp Mode Request
6	SuspLimpModReq	Incoming	boolean	[1]	inherit	Expected signal: Suspension system request for limp mode If signal si NA: mandatory. False	Suspension Limp Mode Request
7	DoorLimpModReq	Incoming	boolean	[1]	inherit	Expected signal: Door closure system request for limp mode If signal si NA: mandatory.	Door Limp Mode Request
8	RampLimpModReq	Incoming	boolean	[1]	inherit	Expected signal: Limp mode Ramp (Driver or passenger ramp /Door) If signal si NA: false	Ramp Limp Mode Request
9	HvLimpModReqVld	Incoming	boolean	[1]	inherit	Expected signal: Hv system request valid If signal si NA: true	Hv Limp Mode Request Valid
10	BrkLimpModReqVld	Incoming	boolean	[1]	inherit	Expected signal: Braking system request valid If signal si NA: true	Brake Limp Mode Request Valid
11	DrvLimpModReqVld	Incoming	boolean	[1]	inherit	Expected signal: Driver system request valid If signal si NA: true	Drive Limp Mode Request Valid
12	SteerLimpModReqVld	Incoming	boolean	[1]	inherit	Expected signal: Steering system request valid If signal si NA: true	Steering Limp Mode Request Valid
13	SuspLimpModReqVld	Incoming	boolean	[1]	inherit	Expected signal: Suspension system request valid If signal si NA: true	Suspension Limp Mode Request Valid
14	DoorLimpModReqVld	Incoming	boolean	[1]	inherit	Expected signal: Door closure system request valid If signal si NA: true	Door Limp Mode Request Valid
15	RampLimpModReqVld	Incoming	boolean	[1]	inherit	Expected signal: Limp mode Ramp (Driver or passenger ramp /Door) If signal si NA: false	Ramp Limp Mode Request Valid
16	LimpSpdLim	Outgoing	uint8	[1]	km/h		Limp Speed Limit
17	LimpReq	Outgoing	boolean	[1]	inherit		Limp Request
18	LimpReqSrc	Outgoing	boolean	[7]	inherit		Limp Request Source

4.19.4. Parameters

	Id	Data Type	Dimensions	Range	Unit	Description	Keywords
1	LimpNoSwt	uint16	[1,1]	Min: 1, Max: 200		Limp Request Change Detection (Switching) Counter Threshold	Limp Number Switch
2	LimpBrkSpdLim	uint8	[1,1]	Min: 0, Max: 255	km/h	Limp Mode Braking-requested Speed Limit	Limp Brake Speed Limit
3	LimpEnaBrkReq	boolean	[1,1]	Min: 0, Max: 1		Enable Braking System Limp Mode Request	Limp Enable Brake Request
4	LimpEnaDrvReq	boolean	[1,1]	Min: 0, Max: 1		Enable Drive System Limp Mode Request	Limp Enable Drive Request
5	LimpEnaHvReq	boolean	[1,1]	Min: 0, Max: 1		Enable High-Voltage System Limp Mode Request	Limp Enable Hv Request
6	LimpHvSpdLim	uint8	[1,1]	Min: 0, Max: 255	km/h	Limp Mode HighVoltage-requested Speed Limit	Limp Hv Speed Limit
7	LimpRampSpdLim	uint8	[1,1]	Min: 0, Max: 255	km/h	Limp Mode Ramp-requested Speed Limit	Limp Ramp Speed Limit
8	LimpEnaRampReq	boolean	[1,1]	Min: 0, Max: 1		Enable Ramp Limp Mode Request	Limp Enable Ramp Request
9	LimpTiSwt	single	[1,1]	Min: 0.01, Max: 100	sec	Limp Request Change Detection (Switching) Time Window	Limp Time Switch
10	LimpTiFltRcvr	single	[1,1]	Min: 0.1, Max: 100	sec	Limp Request Change Rate Fault Recovery Timeout	Limp Time Fault Recover
11	LimpSigLostTi	single	[1,1]	Min: 0, Max: 30	sec	Limp Request Signal Lost Timeout	Limp Signal Lost Time

4.19.5. Calibration

LimpMod software component must be set up in agreement with the set of interacting systems installed in the vehicle. Such system can be source for limp home requests

4.19.5.1. Step 1 - Set speed limits

Enable (set to true ) or Disable (set to false ) the Limp mode requests from the different sources by changing the following parameters:
LimpEnaHvReq for High-Voltage System Limp Mode Request
LimpEnaBrkReq for Braking System Limp Mode Request
LimpEnaDrvReq for Drive System Limp Mode Request
LimpEnaRampReq for the ramp Limp Mode Request (if present). this can be used as door closure if needed

Provide speed limits (in km/h) for the enabled sources when limp mode request is activated
LimpHvSpdLim for High-Voltage System Limp Mode
LimpBrkSpdLim for Braking System Limp Mode
LimpDrvSpdLim for Drive System Limp Mode
LimpRampSpdLim for the Ramp Limp Mode

4.19.5.2. Step 2 - Tune the debounce of the signal to avoid false positive

Set LimpTiFltRcvr in seconds to specify the Limp Request Change Rate Fault Recovery Timeout
Set LimpTiSwt in seconds to specify the Limp Request Change Detection (Switching) Time Window
Set LimpSigLostTi in seconds to specify the Limp Request Signal Lost Timeout

4.19.5.3. Notes

None