A stone retrieval device includes a sheath and a stone retrieval basket that includes a distal region with a plurality of basket wires and a proximal region with one or more core wires. The stone retrieval basket is contained within the sheath and is movable out a distal opening of the sheath to cause the plurality of basket wires to open into a basket shape. The stone retrieval device further includes a lock mechanism that locks the position of the stone retrieval basket with respect to the position of the sheath and a basket force controller that includes a first and a second control stage. The first control stage includes a sensor for measuring force on the stone retrieval basket when the lock mechanism is in an unlocked position, and the second control stage includes a sensor for measuring force when the lock mechanism is in a locked position.