Search Results

Hydrostatic drives offer many advantages in certain vehicle applications. In zero-turn-radius vehicles, advantages such as infinitely variable transmission, high torque transfer, transmission responsiveness, and non-clutching direction reversing make this system the transmission of choice. Currently, most hydrostatic transmissions use mechanical linkages to set the displacement of the hydrostatic pumps. The use of non-linear linkage connections and mechanical damping are used to give the required vehicle drive feel. The use of electrical actuators on hydrostatic pumps along with minimal use of sensors allows the design engineer to replace the conventional mechanical linkages on hydrostatic drive vehicles. In some instances the cost savings gained with the removal of the linkages offset the cost of the electronic circuitry, actuators and sensors.

As the use of electronics increases in vehicles of all kinds, multiple manufacturer compatibility issues begin to dominate the system integration. Functionality of electronics is often repeated and duplicated, increasing costs. In order to reduce costs it is some times necessary to combine the functionality of multiple units into a single package. With the combination of power amplifier electronics and microprocessors, Agile has been able to integrate several vehicle functions into an integrated package. A thorough understanding of the vehicle powertrain dynamics is a critical requirement in developing fully integrated control electronics. Development of integrated electronics begins with a full vehicle model and simulation, followed by prototyping with known electronics before a cost optimized design is proposed. Discussion in this paper will cover full vehicle simulation and assumptions to full vehicle performance and results.