Assembly Definition
This section describes the MDL description of the powertrain in MotionView.
Entities
- Engine and Clutch Body
- This body represents the lumped mass and inertia of the engine and clutch. By default, the body has two attachment candidates with two tags – ‘b_engine’ and ‘b_clutch’.
- Engine Mounts
- The powertrain model by default contains three engine mounts. These mounts are attached to the ‘Powertrain attach body’ which is an attachment body to which the powertrain is connected to (as described in the section below). The Engine and Clutch Body is connected to the attached body via bushings at each mounting positions.
Inputs and Attachment Tags
Input Attachments | Type | Description | Attachment Tag |
---|---|---|---|
Throttle Demand | Solver Variable | Continuous signal between 0 and 1 (scaled by throttle signal scaling factor) that represents the throttle demand by the driver of the vehicle. | sv_throttle_demand |
Clutch Demand | Solver Variable | Continuous signal between 0 and 1 (scaled by clutch signal scaling factor) that represents the clutch demand by the driver of the vehicle. 0 represents a fully engaged clutch, 1 represents a fully disengaged clutch, intermediate values representative of the level of partial engagement. | sv_clutch_demand |
Transmission Speed | Solver Variable | Continuous signal that is speed of the transmission [rad/sec] at the gear box side of the clutch. | sv_transmission_speed |
Gear Demand | Solver Variable | A discreet integer signal that represents the gear the vehicle is currently running at. | sv_gear_demand |
Powertrain Attach Body | Body | The body to which the powertrain needs to be attached. | b_pwr_attach |
Outputs and Attachment Candidates
Element | Description | Units |
---|---|---|
1 | Throttle Position | [0-1] |
2 | Engine Speed | [rad/sec] |
3 | Clutch Slip | [rad/sec] |
4 | Clutch Slip Velocity | [rad/sec2] |
5 | Engine Torque | [Model Units] |
6 | Clutch Torque | [Model Units] |
7 | Throttle Position At Static | [0-1] |
Model Parameters
In order to model different sizes and types of engine and the clutch, the engine and clutch models are parameterized. The parameters are entered into the CSE using Solver Arrays. These parameters can be set using the Data Set present in the assembly.
Parameter | Description | Units |
---|---|---|
Clutch Capacity | The maximum torque the clutch can transmit when fully engaged. | [Nmm] |
Clutch Stiffness | The stiffness of the clutch. | [Nmm/rad] |
Clutch Damping | The damping of the clutch. | [Nmm/rad2] |
Clutch Open | The value of the clutch signal above which the clutch is considered as fully disengaged. * | [No-Units] |
Clutch Closed | The value of the clutch signal below which the clutch is considered as fully engaged.* | [No-Units] |
Clutch Tau | Clutch time constant – the time constant for the clutch-slip decay when the clutch is open (for Anti-Windup). | [sec] |
Clutch Scaling | [Optional] The value by which the Input Clutch signal is scaled with respect to the [0 to 1] scale (Default 1.0). | [No-Units] |
* 0 <= Clutch Closed < Clutch Open <= Clutch Scaling
Parameter | Description | Units |
---|---|---|
Engine Inertia | The combined effective inertia of the rotating parts inside the engine. | [kgm2] |
Rev Limit | The maximum engine speed that can be attained. | [rad/sec] |
Engine Torque Map | The ID of the reference_string that holds the path of the Engine Torque Map. | |
Idle Speed | The engine speed of a free revving engine. | [rad/sec] |
Stall Speed | [Optional] The engine speed at which the engine stalls (Default 0.0). | [rad/sec] |
Throttle Scaling | [Optional] The value by which the Input Throttle signal is scaled with respect to the [0 to 1] scale (Default 100.0). | [No-Units] |
Anti-Stall Flag | [Optional] If set to 1 the anti-stall throttle modulation kicks in at engine speed close to stall (Default switched off). | |
Rev-Limiter Flag | [Optional] If set to 1 the rev-limiter cuts throttle when the engine reaches rev limit (Default switched off). | |
Limit Engine Speed derivative | [Optional] If value > 0 then is saturated at the given value, if value < 0 then it is disabled (Default disabled). | [rad/sec2] |