Stability control system

A drive and control system for use on a vehicle having one or more driven wheels, the drive and control system comprising:

• a plurality of operator inputs, comprising:
• an operator drive input having a neutral drive position and a plurality of non-neutral drive positions;
• and
• an operator steering input having a neutral steering position and a plurality of non-neutral steering positions;
• at least one hydraulic ground drive engaged to and driving at least one driven wheel;
• a plurality of sensors disposed on the vehicle and capable of generating sensor signals corresponding to sensed roll parameters, sensed pitch parameters, and sensed yaw parameters;
• a stability control module comprising a processor connected to the plurality of operator inputs, the stability control module being connected to and capable of providing output signals to the at least one hydraulic ground drive;
• wherein the processor is configured to:
• (a) determine whether the operator drive input is in one of the non-neutral drive positions;
• (b) determine whether the operator steering input is in the neutral steering position;
• (c) if the operator drive input is in one of the non-neutral drive positions, and if the operator steering input is in the neutral steering position, activate a steering correction feature;
• (d) if the operator drive input is in one of the non-neutral drive positions, perform a roll comparison by comparing at least one of the sensed roll parameters to an initial roll parameter and, in response to a first outcome of the roll comparison, limit power supplied to the at least one hydraulic ground drive, enforce a first predetermined maximum vehicle speed or provide an audible or visual warning;
• and
• (e) if the operator drive input is in one of the non-neutral drive positions, provide a pitch comparison by comparing at least one of the sensed pitch parameters to an initial pitch parameter and, in response to a first outcome of the pitch comparison, limit power supplied to the at least one hydraulic ground drive, enforce a second predetermined maximum vehicle speed or provide an audible or visual warning.

A method of operating a vehicle, the vehicle comprising:

• a pair of driven wheels, and a drive and control system comprising:
• a plurality of operator inputs, comprising an operator drive input having a neutral drive position and a plurality of non-neutral drive positions and an operator steering input having a neutral steering position and a plurality of non-neutral steering positions;
• a pair of hydraulic ground drives, each hydraulic ground drive being engaged to and driving at least one of the pair of driven wheels;
• a plurality of sensors disposed on the vehicle and capable of generating sensor signals corresponding to sensed roll parameters, sensed pitch parameters, and sensed yaw parameters;
• and
• a stability control module comprising a processor connected to the plurality of operator inputs, the stability control module being connected to and capable of providing output signals to the pair of hydraulic ground drives;
• the method comprising, via the processor:
• (a) determining whether the operator drive input is in one of the non-neutral drive positions;
• (b) determining whether the operator steering input is in the neutral steering position;
• (c) if the operator steering input is in the neutral steering position, activating a steering correction feature;
• (d) if the operator drive input is in one of the non-neutral drive positions, providing a roll comparison by comparing at least one of the sensed roll parameters to an initial roll parameter and, in response to a first outcome of the roll comparison, limiting power supplied to the pair of hydraulic ground drives or enforcing a first predetermined maximum vehicle speed or providing an audible or visual warning;
• and
• (e) if the operator drive input is in one of the non-neutral drive positions, providing a pitch comparison by comparing at least one of the sensed pitch parameters to an initial pitch parameter and, in response to a first outcome of the pitch comparison, limiting power supplied to the pair of hydraulic ground drives or enforcing a second predetermined maximum vehicle speed or providing an audible or visual warning.

A drive and control system for use on a vehicle having a prime mover, a pair of driven wheels, and a pair of hydraulic ground drives, each hydraulic ground drive being engaged to and independently driving one of the pair of driven wheels to provide zero turn capability to the vehicle, the drive and control system comprising:

• an operator mechanism comprising a pair of control sticks, each having a neutral position and a plurality of operative positions, wherein a separate drive signal is generated by each control stick based on the operative position of the respective control stick;
• each drive signal corresponds to a neutral drive position of the corresponding control stick or to one of a plurality of non-neutral drive positions of the corresponding control stick;
• and
• a first position sensor communicating the operative position of one of the pair of control sticks to a first processor and a second position sensor communicating the operative position of the other of the pair of control sticks to the first processor;
• wherein each of the pair of control sticks generates a speed input value when in one of the plurality of non-neutral drive positions, the speed input value corresponding to a desired speed of the driven wheel corresponding to the respective control stick;
• a plurality of sensors disposed on the vehicle and capable of generating sensor signals corresponding to sensed roll parameters, sensed pitch parameters and sensed yaw parameters;
• and
• a pair of electric actuators, each of the pair of electric actuators engaged to one of the pair of hydraulic ground drives to control the output thereof;
• a stability control module comprising a second processor connected to the operator mechanism for receiving each drive signal and a separate steering signal generated by each control stick based on the operative position of the respective control stick, the stability control module being connected to and capable of providing output signals to the pair of electric actuators;
• wherein the second processor is configured to:
• (a) determine if the steering signal of each control stick corresponds to the neutral drive position or one of the plurality of non-neutral drive positions by evaluating the operative positions of the pair of control sticks;
• (b) measure a differential between the operative positions of the pair of control sticks;
• (b) if the differential between the operative positions of the pair of control sticks is greater than a first predetermined amount, permit the vehicle to operate in a normal zero turn mode;
• and
• (c) if the differential between the operative position of the pair of control sticks is less than the first predetermined amount, and if the steering signal of each control stick exceeds a first predetermined value, then record and store a yaw value of the vehicle as the desired heading of the vehicle and modulate the steering signal of each control stick using a proportional integral derivative control scheme.