A cabin suspension system, adapted to be used in a forestry vehicle, comprising an operator cabin, adapted to control the forest vehicle, spring dampers, mountable between the operator cabin and a vehicle frame, magnetorheological dampers, mountable between the operator cabin and a vehicle frame, sensors, adapted to detect velocity and/or acceleration and/or movement of the cabin, of the vehicle frame and a dampening coefficient of the magnetorheological dampers, and a controlling unit.

A suspension controller includes a target current setting unit configured to set a target current value, a current limitation setting unit configured to set a current limitation value, a current detector configured to detect a current value of a first current supplied to a solenoid that is configured to control a damping force of a suspension, a duty ratio setting unit configured to set a duty ratio based on the target current value, based on the current limitation value, and based on the current value detected by the current detector; and a current outputting unit configured to supply the solenoid with a second current that corresponds to the duty ratio set by the duty ratio setting unit and to a power supply voltage. The current limitation setting unit is configured to change the current limitation value based on the duty ratio set by the duty ratio setting unit.

A suspension controller includes a target current setting unit, a current limitation setting unit, a current outputting unit, a current detector, and an estimated temperature calculator. The target current setting unit sets a target current value. The current limitation setting unit sets a current limitation value. The current outputting unit supplies a solenoid with a current that is based on the target current value, the current limitation value, and a power supply voltage. The solenoid controls a damping force of a suspension. The current detector detects a current value of the current supplied to the solenoid. The estimated temperature calculator calculates an estimated temperature of the solenoid based on the current value detected by the current detector so that the current limitation setting unit changes the current limitation value based on the estimated temperature.

An active vehicle suspension system includes an active damping mechanism operatively coupled to a vehicle wheel and configured for controlling a damping force applied to the wheel responsive to a control signal. A controller is operatively coupled to the damping mechanism and configured for generating a control signal to the damping mechanism responsive to velocity of the wheel in a downward vertical direction. At least one of a timer threshold and velocity threshold, used to determine whether a vehicle wheel has encountered a depression in a road surface, may be varied on a basis of a speed of the vehicle. A damping mechanism for a rear wheel of a vehicle may be controlled on a basis of how a damping mechanism for a front wheel is controlled.

A control device applies a target control force to a variable damping force damper in a suspension mechanism based on a damping coefficient of the variable damping force damper to eliminate unsprung tramp sensations and feelings of hardness when the stroke speed decreases in a conventional skyhook control. The control device includes a state estimation unit for calculating the sprung mass speed of the sprung mass based on a value detected by several of a plurality of sensors, an application control unit for calculating and outputting a damping coefficient of the variable damping force damper based on the calculated sprung mass speed, and a target control amount management unit for determining the target control force based on the damping coefficient output by the application control unit.

An electrically controlled suspension includes a first spring with a first end and a second end, where the first end of the first spring is connectable to a forward frame bracket of a frame of a vehicle and where the second end of the first spring is connectable to a rear frame bracket of the frame of the vehicle via a rear spring support. The suspension includes a second spring with a first end and a second end, where the second end of the second spring is connected to the second end of the first spring. An electrically operated suspension control actuator is provided where the first end of the second spring is connected to the electrically operated suspension control actuator.

A control device applies a target control force to a variable damping force damper in a suspension mechanism based on a damping coefficient of the variable damping force damper to eliminate unsprung tramp sensations and feelings of hardness when the stroke speed decreases in a conventional skyhook control. The control device includes a state estimation unit for calculating the sprung mass speed of the sprung mass based on a value detected by several of a plurality of sensors, an application control unit for calculating and outputting a damping coefficient of the variable damping force damper based on the calculated sprung mass speed, and a target control amount management unit for determining the target control force based on the damping coefficient output by the application control unit.

A shock absorber including a pressure tube, a piston assembly slidably disposed within the pressure tube, and a fluid transfer tube that extends about the pressure tube is provided. The piston assembly divides an inner volume of the pressure tube into first and second working chambers. An intermediate chamber between the pressure tube and the fluid transfer tube is arranged in fluid communication with the first working chamber. A valve assembly is disposed in fluid communication with the intermediate chamber and the second working chamber. The valve assembly controls fluid flow between the intermediate chamber and the second working chamber. At least part of the intermediate chamber is formed by a fluid transfer channel that extends longitudinally within the fluid transfer tube to provide a fluid flow path extending between the first working chamber and the valve assembly.

A control system (300) for controlling an active suspension system (104) of a vehicle (100) to determine relative traction levels, the control system comprising one or more controller (301), wherein the control system is configured to (908): control the active suspension system to change normal force through a first subset of one or more wheels; determine a traction-dependent variable at each of the first subset of wheels to which known torque is applied; control the active suspension system to change normal force through a second subset of one or more wheels; and determine a traction-dependent variable at each of the second subset of wheels to which known torque is applied, wherein the traction-dependent variables indicate relative traction levels.

An electrically controlled suspension includes a first spring with a first end and a second end, where the first end of the first spring is connectable to a forward frame bracket of a frame of a vehicle and where the second end of the first spring is connectable to a rear frame bracket of the frame of the vehicle via a rear spring support. The suspension includes a second spring with a first end and a second end, where the second end of the second spring is connected to the second end of the first spring. An electrically operated suspension control actuator is provided where the first end of the second spring is connected to the electrically operated suspension control actuator.