Underframe with transmission#

The Underframe with transmission block allows to simulate the electric vehicle transmission, generating front \(F_{T,f}\) and back \(F_{T,r}\) forces, which have the same calculation formula and depend on the transmitted torque to the corresponding axle (1):

(1)#\[F_{T,i}=(\frac{\eta \cdot N_{fd}\cdot CMD_{drive}}{r_{t}})\cdot T_{i}+B\cdot CMD_{break}, \]

where

\(\eta\) - Efficiency, [r.u.];

\(r_{t}\) - radius of wheel, [m];

\(N_{fd}\) - main gear ratio;

\(T_{i}\) - torque transmitted to front/rear axle, [N/m];

\(CMD_{drive}\) - transmission command, [r.u.] (from 0 to 1);

B - braking force;

\(CMD_{break}\) - braking command, [r.u.] (from 0 to 1).

In order to avoid exceeding the counteracting force of the axis, the following condition is introduced (2):

(2)#\[F_{T,i}<F_{N,i}\cdot C, \]

where

\(F_{N,i}\) - resultant forces acting on the vehicle axis, [N];

C - static friction coefficient.

1. Properties#

Property	Default value	Description	Units of measurement
Efficiency	0.9	–	-
Radius of wheel	0.32	–	m
Main gear ratio	1.0	The resulting gear ratio depends on the axle ratio and the signal coming to the port `Transmission command`. The resulting gear ratio will be equal to the gear ratio of the main gear if the signal `Transmission command` is 1.	dimensionless
Braking force	10000.0	–	N
Static friction coefficient (buses traction with road surface)	0.9	–	dimensionless
Axle speed threshold threshold	1e-4	–	rad/s

2. Inputs and outputs#

Parameters	Inputs/Outputs	Description	Units of measurement	Port type
Torque on the front axle	Input	-	N\(\cdot\) m	Rotational motion
Torque on the rear axle	Input	-	N\(\cdot\) m	Rotational motion
Braking command (from -1 to 0)	Input	-	dimensionless	Automation
Transmission command	Input	-	dimensionless	Automation
Force generated on the front axle	Output	-	N	Translational motion
Force generated on the rear axle	Output	-	N	Translational motion

In order to see the connection capabilities of the block, you need to go to page Description of block ports