Results and comparison between DCT con- con-trol logics and transmission composed bycon-trol logics and transmission composed by

Figure 3.11: Function integration for computing the notable gear estimation The estimator is therefore created through the parallel use of the existing high level logic, having however as input states the estimates obtained from the previous step and leaving the remaining input states unchanged. Finally, a Matlab function is inserted which recognizes the notable cases at the extremes of the gear changes Figure 3.11.

Taking into consideration the presence of ADAS in the car, it is natural to think that these estimated quantities can be somehow extrapolated from the data relating to the external environment. A first finding is that the speed of the wheels (in non-slip conditions) is proportional to the speed of the car. Knowing therefore a possible speed profile obtained through the use of ADAS, the estimate relating to the speed of the wheels improves considerably.

Other additions can be proposed in the same way for the estimation of Twheel and the f(SoC) but these are not covered in this paper.

3.4 Results and comparison between DCT

the model.

The estimation of the results is carried out by evaluating factors characteristic of motion.

An overall system is then established for the simulation of some reference signals and the subsequent evaluation of the characteristic outputs.

Validation and simulazion

In the Matlab/Simulink environment, an overall evaluation system is then prepared Figure 3.12:

Figure 3.12: Transmission model test setup Within this, it can be noted the presence of:

• Ideal torque source, it is capable of imposing the given torque value. This is considered as the input of the system;

• Inertia, explained earlier. Characteristic values have been assigned specifically for load modeling and to limit the output speed from the ideal torque source;

• Ideal speed sensors, they are used to obtain the speed of the transmission shaft so that it can be evaluated both in input and in output of the modelled

system .

System input

The inputs of the system will be tabulated below. They have been used so that we can evaluate the behavior in both increasing and decreasing shifting gear. To evaluate the response of the model Table 3.3.

Gear_in T_in 0-1-2-1 0-1 Nm

Table 3.3: Input of the test signals for the comparison among the DCT imple-mented control logics and the torque converter + automatic gearbox transmission

For the definition of the inputs, the Signal Builder block is used. It allows the definition of completely custom signals in a precise way.

The gears imposed during the complete simulation of the system are shown below Figure 3.13.

Figure 3.13: Gear input test

Specifically, the following quantities have been washed out and evaluated Ta-ble 3.4:

w_in w_out Clutch_even Clutch_odd

Table 3.4: Output Transmission test signal, they are used for the evaluation of the transmissions model and control performances

For the evaluation of these, there are 2 possible cases of operation of the modeled DCT to evaluate the differences.

In the first case, a total disconnection of both clutches is imposed for a well-specified time interval. In the second, the behavior is shown when the control related to the clutches allows an intermediate value in which both clutches are both partially engaged.

The result of the two simulations is then shown below Figure 3.14:

Figure 3.14: Comparison not-engaged and partial engaged cluthes during gear shift

Specifically, it is noted that the differences in the comparison are marginal in the shift situations, in which the second allows a slightly more continuous transfer of torque. The dashed line shows the ideal trend that should have the angular velocities in the input-output. However, it is clear how the behavior tends to be similar to the ideal one Figure 3.15.

Figure 3.15: Motion transfer comparison between the two implemented DCT control logics

As a second comparison, reference is made to the previous transmission model, which is characterized by the presence of a Torque Converter (TC) with the gear-box downstream. Comparing the two trends shows a particular difference. The TC+Gear configuration shows a strongly non-linear relationship between the in-put speed and the outin-put speed. This occurs due to the presence of the Torque Converter that adds a speed shift between its primary and its secondary, which transfers the motion by dragging. This phenomenon also leads to having a higher input speed at the same final angular velocity of the load Figure 3.16.

Figure 3.16: Motion transfer comparison between automatic gear with torque converter and DCT

For the evaluation of the efficiency concerning the 3 configurations shown, the actual energy transfer that allows a certain load condition must be evaluated.

This assessment was made using the same system shown in Figure 3.12. The energy fed into the system by the ’source’ (in a real vehicle is represented by the motorization) is then evaluated about obtaining a final speed of the load (rotational speed of ωload = 1,72rpm).

The results of this evaluation have therefore been collected and shown in the following table, they are expressed as a relative percentage deviation from the basic configuration (torque converter + automatic transmission) Table 3.5:

Configuration E_source [J] improve % improve [J]

Automatic gearbox +

torque converter 4.545 baseline baseline

DCT configuration all clutches

disengaged during gear shift 3.302 27,35 -1,24 DCT configuration clutches

partially engaged during gear shift 4.545 26,6 -1,21

Table 3.5: Output Transmission test signal, they are used for the evaluation of the transmissions model and control performances

The results show that the DCT configuration is more efficient, as it manages to impose a certain state on the load with less energy. In relation to the type of control configuration present in the DCT, the differences show how the control with partial presence engagement of both clutches is more efficient.