Technical information

DRV Final Evaluation Report

arises when the work zone is close to the vehicle as found when retrieving debris next to

a sound wall or on a narrow shoulder. In both of these cases the garbage can be dumped

but it takes more tedious manipulation of the arm by the operator, hence, decreasing the

efficiency of the machine. With further investigation, modes could be implemented

where different code sections are executed based on the environment selected by an

operator. The ideal solution may not be just a programming modification, but rather a

conceptual change in how garbage is dumped once retrieved and the design of the arm.

The type of debris encountered can be better defined now that testing has occurred. The

type of debris directly affects two areas of the design, the clam shell and the weight

capacity. The design of the clamshell works geometrically for the majority of debris.

The few exceptions are loose objects that can fall out of the clamshell, such as a soda can

or other small objects that were not placed in bags, and objects that are two long such as

lumber. Lumber either slips from the grip of the clamshell or jams it open making it

difficult to dump. Tumbleweed was also retrieved using the DRV. The complication

with tumbleweed was keeping it in one place. Stacked in piles it is easily blown away or

disrupted when encountered by the clam shell. Although the DRV was successful at

retrieving the tumbleweed fairly efficiently, a vacuum type machine would be better

adapted. With the exception of the tumbleweed, these items are a small percentage of the

debris retrieved but are reasonable to consider in the design of the end effector. The

heaviest items encountered were bags of ice plant. It is possible to exceed the lifting

capacity of the DRV’s arm with a full load of ice plant in certain geometric

configurations of the arm. Changes to the kinematics of the arm would have been

reasonable at the time of the rebuild, however, a new design would be prudent. The

lifting capacity of the arm was sufficient for the remainder of the debris encountered

during testing.

Evaluation of Machine Effectiveness

The efficiency of a machine is hard to determine without a controlled experiment. Data

was gathered regarding how many bags of garbage the DRV retrieved in a given trip, but

it does not state if there were more bags available to be picked up or not or the amount of

time it took. It does not state how distributed the debris was or if the debris was stacked

properly for the DRV to work as designed. In addition, it must be established whether

the number of bags, the volume, or the weight of the debris retrieved is of importance in

measuring the DRV’s effectiveness. The operation of removing debris using the DRV is

a single person operation. Arguments are made that current operations only use one

person also, however, probate workers are not counted yet do reflect a safety risk.

Therefore, the statistics can be listed but comparisons should be made cautiously.

Records of the DRV’s usage have been kept but with limited information. The number of

bags retrieved display an uneven distribution. It appears that many times all the bags

available were picked up and report an average of 150 bags in a trip. Other data shows

that 350 bags in a trip were retrieved, implying that more bags were available and maybe

placed in a convenient manner. Data regarding how long it took in the shift to retrieve

the debris has not been recorded to date. Observation indicates that if the debris is