PLC based program for extraction of seed from a Fruit

Existing Process: It’s a process to extract seed from a fruit. Prime requirement is of seed. Already have mechanism to pick single fruit at a time, put it in clamp and send it (on conveyor belt) to the cutter. The Tool cutter is stationary and is placed at a point which is vertically above the moving fruit. The tool is stationary and permissible movement is moving downwards to cut the fruit into 2 parts and thus extract the seed. Issue facing: Fruit have different size 25 mm to 40 mm thus movement of tool cutter vertically downwards is a problem and thus many fruits passed through the cutter without cut. Mechanism required: 1. To calculate the size (height) of fruit while on conveyor belt. 2. A mechanism to make movement of cutter vertically downwards (according to the height of fruit) when fruit is below the cutter. Relevant information: 1. Fruit is 25 mm to 40 mm in height and around 25 mm thick. Already have mechanism to clamp the fruit in vertical shape. 2. One fruit cut at a time by the existing blade. 3. Need pneumatic or hydraulic arrangement for downwards movement of cutter. 4. The cutter movement is just around till 20-25% of height of fruit as fruit is brittle and thus split into two parts. Need a functional device (with details) to execute the task.