System And Method For Controlling Wheel Spin And Wheel Slip On A Machine Having Differentially Driven Wheels

An electronic traction optimization system for a machine having a transmission operably coupled to a front axle and a rear axle, two wheels coupled to each of the front and rear axles, and a cross-axle differential disposed between each of the front and rear axles, the system comprising:

• a wheel speed sensor associated with each wheel and adapted to generate a wheel speed signal;
• an orientation sensor responsive to an orientation of the machine from which a yaw rate signal is derived;
• a differential clutch associated with each differential, each differential clutch including a torque transfer mechanism configured to override the associated differential and an actuator configured to operate the torque transfer mechanism;
• a control unit adapted to:
• produce a corner speed estimate signal for each wheel having a value responsive to the wheel speed signals and yaw rate signal;
• produce an ideal target speed signal having a value responsive to the corner speed estimate signal associated with each wheel;
• produce at least one practical target speed signal for each wheel having a value responsive to the wheel speed signals;
• derive an actual target speed signal from the ideal target speed signal and the at least one practical target speed signal for each wheel;
• compare each actual target speed signal to an associated wheel speed signal to obtain a wheel speed error signal for each wheel;
• and
• convert each wheel speed error signal to a clutch control signal, wherein each differential clutch actuator is responsive to the clutch control signal.

A machine, comprising:

• a front axle including a left axle shaft, a right axle shaft, and a front axle differential disposed between the left and right axle shafts;
• a rear axle including a left axle shaft, a right axle shaft, and a rear axle differential disposed between the left and right axle shafts;
• a wheel attached to each axle shaft;
• a main power source for generating torque;
• a transmission coupled to the main power source for receiving the torque and having a transmission output shaft operably coupled to the front and rear axles;
• a front axle differential clutch operably coupled to the front axle differential, the front axle differential clutch including a torque transfer mechanism configured to override the front axle differential, and an actuator operably coupled to the torque transfer mechanism;
• a rear axle differential clutch operably coupled to the rear axle differential, the rear axle differential clutch including a torque transfer mechanism configured to override the rear axle differential, and an actuator operably coupled to the torque transfer mechanism;
• a wheel speed sensor associated with each wheel and adapted to generate a wheel speed signal;
• an orientation sensor responsive to an orientation of the articulated truck from which a yaw rate signal is derived;
• and
• a control unit adapted to:
• produce a corner speed estimate signal for each wheel having a value responsive to the wheel speed signals and yaw rate signal;
• produce an ideal target speed signal having a value responsive to the corner speed estimate signal associated with each wheel;
• produce at least one practical target speed signal for each wheel having a value responsive to the wheel speed signals;
• derive an actual target speed signal from the ideal target speed signal and the at least one practical target speed signal for each wheel;
• compare each actual target speed signal to an associated wheel speed signal to obtain a wheel speed error signal for each wheel;
• and
• convert each wheel speed error signal to a clutch control signal, wherein each differential clutch actuator is responsive to the clutch control signal.