### The Concept of Robot Wear  
Gearboxes are often mentioned as the component that is frequently responsible for a failure of rotary machines [18], including industrial robots [19]. The most critical components of a gearbox are the gears and bearings. The deterioration of a gearbox at the teeth [20; 21], harmonic drive gears are damaged by fatigue fractures [22], and bearings are typically subjected to failures at the rolling elements or the inner or outer race [21]. The damage accumulates over time and is caused mainly by load (forces and velocity) [23; 24], high temperature [25], bad lubrication [26], or manufacturing defects. The performance, accuracy, and lifetime of a robot relies on the good condition of these critical components [27].  
The authors in [28] proposed a method for estimating the wear of a robot by monitoring the temperatures in the joints, while [29] suggested a more complex solution, where other parameters are also monitored in order to predict the lifetime of a multi-component system. Other common properties monitored to predict the lifetime of a machine include vibrations and noise [21]. A generic framework for predictive maintenance based on simulation models with degradation curves discovered from real data was proposed in [27]. Our approach, on the contrary, attempts to minimize wear by the use of a quite simple simulation in the design stage of a robotized workplace instead of monitoring an already existing one.  
As mentioned above, the gearbox in the robot manipulator joint can be considered the most important source of the wear of the joint. The electric motor in the joint is subject to deterioration as well [30]. As far as the above-mentioned sources of wear are concerned, the most important is the load combined with movement velocity, because a higher velocity creates higher temperatures. This applies to both the gearbox and the motor. The influence of bad lubrication or manufacturing defects are almost impossible to anticipate or even simulate and, thus, are not considered in this work.  
A typical robot joint contains structural bearings that provide the mutual rotational movement of the joints. However, obtaining the values of the reacting forces required to calculate the wear of these bearings is not an easy task, even when using a dynamic simulation. This requires an exact simulation model of the robot with a detailed representation of the inner parts and mechanisms, accurate values of the mass properties, acceptably realistic values of the friction coefficients, and a good dynamic simulation engine. Although it is usually possible to obtain 3D models of commercially available industrial and collaborative robots, and sometimes even simulation models prepared for common simulation systems, these models typically are simplified and do not contain the inner mechanisms of the arms.  
On the other hand, wear of the gearbox and motor can be expressed as torque that the motor must generate (and that the gearbox must transfer to the joint) over some trajectory of motion. These values depend on physical quantities that are much easier to obtain from a simulation--the overall path of motion (kinematics) and the required driving torque required to achieve the given acceleration (dynamics).  
The hypothesis of our research is that the lifetime of a robot in a robotized workplace can be improved in the design stage by designing the workplace (namely the location of the robot) in such a way to ensure lower wear of the robot joints.