Modelling and Control of a
Six-wheel Forwarder
Liselott Ericson, Alessandro Dell’Amico and Petter Krus
Concept
The forwarder has a hydraulic motor mounted on each wheel which
can individually control the speed or torque. The forwarder has
pendulum arms for each wheel which enables even ground pressure.
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Method
Problem
During forest harvesting, the forest machines will have a more or less
negative impact on the soil, which could lead to problems, such as
further growth at replanting. One of the main reasons for this is wheel
slip.
To find the best system solution and control concept the whole
transmission is simulated in Hopsan and further connected to
Adams to find the correct forces on the wheels.
Control Strategies
Purpose
The purpose is to develop a control strategy to minimise soil damage
and increase productivity. This has to be assured while minimising
energy consumption.
To different secondary control strategies are considered: Torque
control and speed control. The strategies has both pros and cones.
Torque control has an inbuilt differential however needs a
separate control loop with a kinematic model when slip is to be
controlled. The speed control strategy needs an accurate
kinematic model to control the differential speed however no
additional control strategy is needed for control of the slip. The
speed control strategy does not need system pressure
measurement which makes it easier in a control point of view..
Linköping University, Fluid and Mechatronic Systems, www.iei.liu.se/flumes, [email protected], 2015-03-10