Robotic Joints and Subsequent Environmental Effects

Industrial automation demand feeds on automotive manufacturing. This demand ties it to a 3C-principle of consumer, communications, and computer electronics. The traditional production lines relied on dedicated equipment performance, but robots have the advantage of superior capabilities and operational flexibility. They rapidly respond to the shift in consumer and market demands. The article takes a look at how the environmental effects can influence the motion of such robotic components.

Basic Overview of Robotic Joints

The industrial robots are considerable as control-automated programmable multipurpose manipulators who operate in three-or-more axes to move given load(s). The evolution and sophistication of the modular robotic joints provide credit to the significant advances in control and actuator technology. The standardization of the modular robotic joints does not inhibit their flexibility to interface with other component s and systems. Modularity paves the way for versatility in ease of assembly, adaptability, and machine design capabilities. Lower weight, reliability, dynamic performance, and higher power density makes the integrated mechatronic modular joints a better performing candidate than the conventional robotics.

The robotics industry’s servo-motion components should be a memorized manual by every motion-component manufacturer. The optimization of the OEM designed cobot (collaborative robot) should consider lighter payloads to facilitate the inclusiveness of the modular robotic joints. The simplicity and safety design principles lure the integration of frameless torque motors by the modular robotic joints as PMAC (Alternating Current Permanent Magnet) servo motors. The optimization of safety engineering principles translates to the adherence of the frameless motors to reliability and performance requirements or space and weight constraints.

The Thermal Environmental Effects

The degradation of an industrial robot’s lifespan is viable through high temperatures. A simple, compact housing of a mechatronic robotic joint module will, for instance, contain connection cables, torque sensors, resolver or encoder, brake, a dedicated gearing system, servo drive, and frameless motor.

The regular operation under such housing will dissipate heat. Such heat emission originates from the applicable break coil, motor windings, gearing, and other related electronic and electric components. The use of strain-wave gearing will significantly contribute to the environmental heat emission if the gearing component is in operation. Viscous-lubricant shear friction and gear-mesh friction applicable to the gear component contribute to a 30% total power loss. The percentage loss is also inclusive of the repeated distortion of the invested energy to cater for the subsequent revolutions of the metallic flexspline. Thus the buildup of such ineffective heat dissipation leads to the robot overheating and facilitate its diminished performance.

Strain-Wave Gearing

The output shaft typical rotation speed of a robotic joint is between 10 and 40 rpm. The short bursts rotations of a motor triggered by robotic joint movements are between 1,000 and 4,000 rpm. Thus gearing causes a reduction in speed and an increase in the torque’s output acceleration. It applies to the torque-per-unit mass (specific toque) and the torque-per-unit volume. A circular spline, a flexspline, and an ellipse-shaped wave generator make up the strain-wave gearing. The life-limiting sub-component is the flexspline. Its operational rotation demands minimal angular deflections. The ellipse-shaped wave generator, however, produces constant changes in the elastic deformation. Therefore, the accuracy in transmission of rotational motion requires the flexibility of the flexspline. It should be in the radial direction and its stiffness in the tangential direction.

Various mechanisms contribute to the strain-wave gearing power loses. They include mechanical loss, bearing friction loss, lubricant’s viscous friction, and gear meshing friction.

Electrically Actuated Brakes

They are a commonality in industrial robots. An electromagnetic inductive coil facilitates the applications’ brakes. It comprises of a mechanical spring mechanism that works with holding friction that is active when the coil loses voltage support. Thus motor movements energize such break coils and, in turn generating heat.

Environmental Temperature

When the design objectives consider weight and size, then it fits the criterion for frameless motor applications. Custom designed flexibility, enhancements in heat dissipation capabilities, and high torque density are some technical and commercial competitive advantages the end users can benefit from if they chose this motor type.

If there is a mismatch between the rated motor values and the environmental temperature such that it exceeds, there will be a deterioration in the motor performance. Moreover, there would be a lag in its speed due to reduced torque. If power loss is tied to winding resistance, then the contributive factors will be the electrical resistance and current. The operating speed is the motor’s key design objective.

Robotic Sensors Heat Sensitivity

Torques, resolvers and encoders sensors are some of the many sensors robots use. The sensors’ key characteristic is the level of their sensitivity to the environmental temperature changes. Increased temperature will cause the optical encoders to reduce the output LED light. The performance of the optical encoder will also feel the impact of thermal expansion. A situation can arise where the air gap between the source and the disk is narrow due to thermal expansion. If such instances become extreme, the sub-components might make contact and, in turn, cause catastrophic failure or encoder damage. An altered magnetic poles pitch will lead to the alteration of the needed output for the case of a magnetic wheel affected by thermal expansion and contraction.

Electronic Components Like Servo Drive

Medical robots, industrial articulated robots, and cobots objectify their performance on servo drives. High temperatures, however, skyrocket the failure of such electronic components. A high temperature will subsequently result in high thermal noise levels that are against performance. Thus managing the operational temperature will resultantly manage the thermal noise content.

Robotic Joints and Bearing Lubrication

Both the strain-wave gearing and motor performance get significant influence from lubrication. The regular deep-groove ball bearing, wave generator bearing, and cross-roller bearing are an example of bearings applicable in robots. The mineral oil-base greases provide their lubrication. Environmental conditions, lubricant properties, load, velocity, and temperature are the contributive factors that affect bearing friction. Molecular-friction and grease-viscosity changes result from temperature changes. System ware or failure can also arise from reduced temperatures that cause insufficient lubrication due to altered oil-release characteristics. Additional issues like oil oxidation will cause an increase in deposits and oil viscosity. Thus it will be impossible for the lubricant to create a protective lubricant film.

Harsh Environmental Effects

The design of some industrial robots favors their operation in harsh environments. They include polishing and grinding robots, welding robots, and spray-painting robots. Thus corrosion, humidity, dust, and muddy terrains, among other conditions, influence how a robot performs. The exterior coatings of the industrial robots will determine their adaptability to such terms. Thus the design of such robots can also influence their corrosive settings.

Loading and Vibrations During a Robotic Operations

The position control accuracy and the dynamic characteristics of a robot are affected by the overall system inertia and robot payload. The robot payload is the weight a robot lifts and moves other than its mass. The gearing teeth are at risk of fractures if a robot tries to handle a high payload. Thus such mechanical overloads can lead to teeth breakage due to tensile strength effects. If a very high inertia tags along with an acceptable payload assigned to a robot, the robotic acceleration is likely to reduce, malfunction, or even breakdown. It is, therefore, a recommendation to consider the applied contact force and the payload inertia.

It is thus essential to have a full understanding of a robot in terms of its workable speed, the limits of its movement ranges, and the maximum payload it can handle. Such factors are the beginning of unwarranted environmental factors that can send a viable robot to an early grave. Thus if the dynamic stability factor gets resolved, workplace safety and robotic performance will be easily manageable.

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