Technical information

DRV Final Evaluation Report

reported complaints by any operators regarding the use of a joystick relating to comfort

or effort.

The efficiency of the DRV is related to the experience of the operator and its integration

into the debris removal program plan. The more frequently that an operator used the

machine the more efficient the operation became. There were several techniques

operators employed as their exposure to the machine increased that sped up the operation.

If bags are not stacked closely together, it is often more efficient to grab several bags

with the machine and then placing them on an adjacent pile, retrieve the full load of

garbage. The cycle time for dumping garbage requires as much debris to be gathered as

reasonably possible to make the process efficient. In addition, the operator can drive

from one pile to another while the machine is completing the dump cycle. The speed of

the arm was limited by its structural integrity not the hydraulic power or flow restrictions.

Since the existing arm was used, the performance of the system was detuned to avoid

accelerations that could exceed the limitations of the arm. A better designed arm would

allow for increases in the speed of the operation. As important as operator experience is

the execution of the program plan. The workspace of the DRV must be considered when

debris is gathered and bags are piled up. If the operator has to exit the vehicle to move

debris within the workspace then the purpose and efficiency of the process is greatly

reduced. In addition, the debris should be piled such that a maximum payload is obtained

without repositioning the manipulator or executing an inefficient dump cycle. Crews

gathering the debris have to be aware of the machinery being used to remove the debris

from the roadside.

Evaluation of Machine Design

The DRV is a versatile machine that allows an operator to retrieve a wide range of debris

in many different environments. By the nature of a prototype machine, many

complications are not conceived until adequate field testing is completed. Two areas of

complications were the type of debris encountered and the diverse terrain.

The robotic arm on the DRV is designed to retrieve the garbage from a large workspace

and then dump it into the compactor body. In order to allow the machine to dump

garbage automatically without feedback of its surroundings, many assumptions must be

made when scheduling the sequence of motion. The control sequence that was

implemented works great for the majority of the work; however, there are two cases

where complications arise. Working on a bank creates a problem for the automated

dumping sequence and the preset motion sequence. Preset positions have to be set to stop

the manipulator higher, relative to the roadway, on banks in order to prevent the

manipulator from driving into the ground. The programming of the presets can be

accomplished quickly by the operator with simple commands entered from the joystick.

The automated dump sequence is hard coded in the controller and requires more effort.

Simply, changing presets is a software feature where changing the dump sequence is an

algorithm consideration. The problem with the automated dump command on banks is

related to the sequence of events and that the arm starts at a much higher position.

Adding more software features could eliminate this complexity. The second problem