Biological and Agricultural Engineering

Machine Systems Engineering

Our department has a long history of success in developing machine systems for fruit, nut, vegetable, and field crops. Tractors, implements, and harvesting machines have been studied, improved, or developed from basic concepts. Harvesters for processing tomatoes, wine grapes, cantaloupes, dates, fresh market tomatoes, asparagus, prunes, peaches, and raisins were firsts for the department. The emphasis placed on this endeavor reflects the important status of California as a producer of a wide range of horticultural commodities. The state is a major producer of rice, other grain and seed crops, sugar beets, and hay. Out of a list of 126 major and minor fruit, nut, and vegetable crops grown in the US, nearly 60% are represented in California. In fact, California is the leading producer of 47 and the second leading producer of 17 of these US grown commodities.

California grows approximately 7.5 million acres of field crops, 1.8 million acres of fruit and nut crops, and 0.9 million acres of vegetable crops annually—for a total of 10.2 million acres. In contrast to agricultural land in other parts of the country, this acreage includes 10 crops occupying over a quarter million acres each.
This diversity and volume, in combination with the need to irrigate many of these crops in our climate, result in many special agricultural equipment needs.

The department’s research on machine systems focuses on two main areas: 1) development of the working principles for machines suited to the special needs of production in California and similar production systems worldwide, and 2) the search for fundamental knowledge about the principles of how equipment interacts with soil, plants, or biological products, and how equipment can be made more efficient and economical to operate. Large equipment manufacturers conduct research to develop and improve machines for use throughout the country. Many smaller companies in California produce specialty equipment but are unable to finance major research programs. The department devotes its attention to meeting machine research needs not met by either large-scale manufacturers or small-scale California firms. Faculty and graduate students also undertake research on fundamental engineering topics which have applications nationwide and, frequently, internationally.

In recent years, much of our interest has been in precision agriculture. Precision agriculture is a farming concept that optimizes fertilizer, pesticide, water use, etc., while minimizing environmental concerns. This is done by treating each unit of field (as small as several square meters) differently with respect to inputs such as fertilizers, pesticides, water management, plant population, etc., rather than by treating the whole field in a uniform fashion. Data such as yield (amount and quality), soil and plant characteristics, pest populations, etc., are used in crop response models to decide on water and fertilizer requirements, pesticides, and cultural practices that will maximize return (usually economic) and minimize adverse effects (usually environmental). Our research and development focuses on integration of Geographic Information Systems (GIS) with Global Positioning Systems (GPS) and Variable Rate Technologies (VRT). New crop/soil sensors and remote sensing techniques are under development in the department, especially for crops relatively unique to California.

The Joe A. Heidrick, Sr. Western Center for Agricultural Equipment was completed in 1998. This 18,000 sq. ft. building accommodates teaching, research, and extension pertaining to agricultural field equipment suitable for the western US. The facility, created through a joint partnership between the university and the agricultural industry, has a wing of the building devoted exclusively to the agricultural equipment industry for conducting service training of dealer personnel. This close affiliation with the industry allows for excellent communication and collaborative research with engineers from the major and shortline manufacturers of agricultural equipment.



This mobile, single pneumatic wheel traction testing device was constructed to assess all-terrain tires for their traction performance and soil compacting effects on fields of different soil types and moisture contents.



Successful projects often require the integration of a number of disciplines. Here a machine vision system is used to detect weeds along the roadside and trigger an automatic sprayer to treat them with herbicide. The system can reduce the amount of chemical introduced into the environment



The drop size spectrum produced from this agricultural sprayer is a basic factor that affects droplet trajectories, drift losses, evaporation, type of coverage, and efficacy of pesticide applications. The laser hardware directed into the spray stream rapidly measures and classifies the sizes of droplets. The system therefore offers a rapid, accurate means to evaluate the basic effects of nozzle designs and various operating parameters.


Targeted application of agricultural chemicals can reduce adverse environmental effects. Here a spray control system developed by our researchers detects and measures orchard trees, determines how much spray to apply, and automatically applies it.


This intelligent robotic weed control implement for row crops was developed by our researchers and is being perfected in field tests by this student. The prototype travels at approximately 60 ft/min to remove in-row weeds using machine vision and a precision chemical application system.



One of the important key elements in the development of large four wheel drive tractors has been the design and construction of the tractor tire. Our studies have shown that by operating radial ply tires with proper inflation pressure (as low as 8-14 psi) the following benefits result: increased traction, efficiency of all tillage operations, faster tillage speeds, reduced compaction, reduced power hop, and fuel savings



Machine vision is used in this computer guided cultivator. Speeds of up to 10 mph and a cultivation accuracy of half an inch have been demonstrated in tomato fields. Current work focuses on distinguishing weeds from plants within the seedline.



A tomato yield monitor has been developed by our researchers for mapping variability in the field. This system measures the total yield (green and red) and uses a differential global positioning system (DGPS) to map yield differences.



A texture/soil compaction level sensor has been developed for use in precision agriculture of vegetables. This device uses a speed sensor, depth sensor, load sensor, moisture sensor, and GPS to map the texture/compaction level with-in a field.