Method and apparatus for controlling a bucket and thumb of a work machine

A method of controlling the clamping force on an object being held between a bucket and a thumb of a work machine, comprising the steps of:

• producing at least one pressure signal indicative of the pressure applied by the bucket and thumb on an object being held therebetween;
• producing an operator control signal;
• and
• receiving the at least one pressure signal and the operator control signal and responsively delivering command signals to a reciprocating device in order to control the pressure applied by the bucket and thumb on an object being held therebetween.

An apparatus for controlling the clamping force on an object being held between a bucket and a thumb of a work machine, comprising:

• an electronic controller;
• at least one bucket hydraulic cylinder having head and rod ends and adapted to move the bucket;
• at least one thumb hydraulic cylinder having head and rod ends and adapted to move the thumb;
• at least one bucket head end pressure sensor electrically coupled to the electronic controller and adapted to produce a bucket head end pressure signal indicative of the pressure at the head end of the at least one bucket cylinder;
• at least one bucket rod end pressure sensor electrically coupled to the electronic controller and adapted to produce a bucket rod end pressure signal indicative of the pressure at the rod end of the at least one bucket cylinder;
• at least one thumb head end pressure sensor electrically coupled to the electronic controller and adapted to produce a thumb head end pressure signal indicative of the pressure at the head end of the at least one thumb cylinder;
• at least one thumb rod end pressure sensor electrically coupled to the electronic controller and adapted to produce a thumb rod end pressure signal indicative of the pressure at the rod end of the at least one thumb cylinder;
• an operator interface for producing a pressure set signal, a pressure release signal and a mode signal having automatic, computer assisted and program modes;
• a memory in communication with the controller and adapted to store a plurality of bucket and thumb head and rod end pressure signal values;
• and
• wherein the electronic controller receives bucket and thumb head and rod end pressure signal values, the bucket and thumb head and rod end pressure signals, the pressure set signal, the pressure release signal, the mode signal and in response to the mode signal being automatic mode the controller delivers command signals to the bucket and thumb hydraulic cylinders in order to control the pressure applied by the bucket and thumb on an object being held therebetween to the bucket and thumb head and rod end pressure signal values in response to the pressure set signal and to substantially no pressure in response to the pressure release signal, in response to the mode signal being computer assisted mode the controller delivers command signals to the bucket and thumb hydraulic cylinders in order to maintain the pressure applied by the bucket and thumb on an object being held therebetween in response to the pressure set signal and to substantially no pressure in response to the pressure release signal and in response to the mode signal being program mode and the pressure set signal the controller reads the bucket and thumb head and rod end pressure signals and stores corresponding bucket and thumb head and rod end pressure values in memory.