In order to successfuly navigate between rows of plants, automated strawberry harvesters require a robust and accurate method of measuring the distance between the harvester and the strawberry bed. A diffracted red laser is used to project a straight horizontal line onto the bed, and is viewed by a video camera positioned at an angle to the laser. Using filtering techniques and the Hough transform, the distance to the bed can be calculated accurately at many points simultaneously, allowing the harverster's navigation system to determine both its position and angle relative to the bed. Testing has shown that this low-cost solution provides near-perfect field performance.