RLS4WD Module V.1.7.0

The module is used to simulate a four-wheel drive road load with varying slip for each wheel in order to support agricultural surface models. The speed control is realized using the CMEM modules, so the machine speed targets as output.

Input and output signals refer to machine level supporting up to four machines. Depending on the chosen configuration, drives are assigned to vehicle level wheels or axles first. Based on the active control mode, vehicle level target speeds are manipulated further. Finally they are converted to machine level again. Outgoing machine level target speeds can be passed to speed controllers, e.g., CMEM modules, or used otherwise.

Figure 105. Module Structure Overview with Example Interfaces

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The total tractive force has to display the effective tractive force acting on the vehicle body resulting in its acceleration/deceleration.

It is computed by adding up all activated drive force inputs.

Note Depending on the test bench type and setup, you must take appropriate measures to provide proper tractive force inputs.

Example 1: Chassis Drive with Force Acquisition Between Rollers and Machines

The accelerating force term(s) of the roller(s) and other inertial components between wheel surface and force/torque transducers have to be added to the measured force(s).

Also any test bench related losses, e.g., bearing friction, have to be eliminated from measured force(s).

Example 2: Force/Torque Transducers at Powertrain Level

If the force/torque is measured directly at the powertrain shaft, e.g.,, at the wheel shaft or vehicle gearbox output, there is no need to compensate for the accelerating force term if the mechanical properties, especially the total rotational inertia, are roughly equal to the real world setup.

A torque measured at a wheel shaft can be used directly after conversion to force.

A torque measured at gearbox output has to converted to wheel axle level by considering an axle ratio.

It is also possible to scale the total tractive force. This feature is aimed at test bench setups with only a fraction of the tractive force producing components available, compared to their real world use in a vehicle.