Technical information

DRV Final Evaluation Report

implement with a standardized interface allows for the adaptation to debris localized to a

single region not considered at initial development. In addition, the ideal design for 70

percent of the work should not be compromised by accommodating the other 30 percent.

Payload capacity is always a concern. Field testing found that retrieving large piles of

green ice plant were the heaviest task encountered in the Southern California region. It is

possible that a pile of ice plant weigh on the order of 350 pounds.

A clear definition of the task space for each component of the machine must be

established. To accomplish this, a clear description of the debris removal plan must exist.

How versatile the arm needs to be is described by how the debris is distributed on the

roadway and the degrees of freedom in the arm’s workspace. If all the debris to be

removed from the roadside is first stacked by a crew, then the complexity is greatly

reduced. The debris can be conveniently piled in a location that requires minimal

dexterity in the arm, hence eliminating the need for redundant degrees of freedom. If the

arms task is only to retrieve the debris from the roadside and another component transfers

it to the refuse container, then the complexity of the arm is again reduced, however, it

may increase the complexity of other components on the machine. Reaching over objects

such as guardrails and side of hills increases the need for complexity in the arm design

and is usually only needed due to deficiencies in the debris removal plan. The workers

gathering the debris were not aware of the machine being used to retrieve it and the

proper way to place the debris in anticipation of its use. The ability of the arm to retrieve

debris from both sides of the vehicle is a crucial design consideration. This allows the

machine to work on the median and the shoulder. The key element in the success of

implementing a design is the proper execution of the developed debris removal plan

around which the machine was designed.

Control process needs to allow for operator multitasking. While the control software

performs many multitasking operations, the ability of the operator to multitask was

limited by machine design. For example, an arm could retrieve debris from the roadside

and place it on a transfer component that would transfer the debris to the refuse container

while either the arm returned to the roadside for another load or the vehicle was driven to

the next location. In other words, while the machine is performing automated tasks the

operator should be able to perform other tasks if possible.