Addressing industry needs with custom encoders

Criteria

There are numerous types and styles of standard, off-the-shelf encoders that are currently available on the market. Unless the encoder is ideally matched to an application’s mechanical, electrical and software configuration, a custom encoder may be required. Numerous criteria must be considered when selecting an appropriate encoder for a given application. Among them are resolution and accuracy, environmental protection, geometry and mounting, and maximum speed.

Resolution and accuracy

An encoder’s resolution is the smallest incremental measurement that can be made, corresponding to one pulse or count. The encoder resolution can be expressed in terms of pulses per distance for linear measurements or in pulses per revolution for rotational measurements. An encoder’s accuracy, on the other hand, refers to the deviation between the actual and theoretical position reported by an encoder, and concerns the maximum error of a position reading.

Environmental protection

Depending on the application, encoders must be tested and qualified for different operating environments. This is because numerous environmental factors may impact the resolution, accuracy and reliability of an encoder. These environmental factors may include contaminants, such as dirt and dust, moisture, temperature changes, shock, vibration and radiation environments.

Geometry and mounting

Some encoders may need to be packaged to fit into applications with strict size, weight and mounting constraints. These encoders may need to have custom geometries or be miniaturized without compromising resolution and accuracy performance, reliability or their ability to operate under adverse operating conditions and environments.

Maximum speed

If an application requires high speed or high resolution, both the mechanical and electrical speed limits of the encoder must be considered. Traditional encoders that are equipped with mechanical bearings are often limited by their rotational speed. This is because higher rotational speeds result in higher operating temperatures that may break down the bearing lubrication. Electronically, the encoder’s maximum speed is limited by the bandwidth or frequency response of the motion controller.

Although there are numerous applications where standard off-the-shelf encoders are available, some applications may require custom encoders to satisfy all the above design criteria.

Custom encoders

Custom encoders can incorporate non-standard mechanical and electrical features. For encoder geometry to physically fit into different applications, the printed circuit board (PCB) may incorporate different sizes, shapes or mounting configurations. Furthermore, the PCB support material and housing can be made of alternative materials to satisfy thermal, moisture, radiation, shock and vibration environments. The encoder interface to the motor may also incorporate specialized shaft and ring geometries to enable its use with different motors and configurations. Electronically, the encoder may have a non-standard resolution, or be equipped with custom electrical interfaces and interconnects. The encoder can also be customized to be compatible with different software codes and parameters and output specific to diagnostic information, ensuring its reliable operation and performance.

The above advantages enable custom encoders to operate in a variety of applications. However, customization has several disadvantages. Depending on the extent of modifications required, customization has inherently higher technical and program risks, and may require a longer time-to-market since an extensive amount of design, development and testing may be required. These disadvantages may ultimately lead to higher development and product costs.

Kit and modular encoders
Figure 1. Lika kit encoder. Source: Lika Electronic

Lika Electronic manufactures kit and modular encoders that make it easier for end users to incorporate high precision and accuracy into non-standard applications, while reducing the downside risks of fully customized encoders. These encoder products may be readily configured for numerous applications, and they greatly reduce development risk, time and cost. They are engineered for direct integration into robotic systems, motors and numerous other applications where small size, low profile, minimum weight, high resolution and high accuracy are required for precise position and speed feedback operations.

Kit encoders are optical encoders in a frameless design (Figure 1), whereas modular encoders pair magnetic encoders with a magnetic ring (Figure 2). These encoder designs offer several advantages. They are shaftless, bearingless and do not incorpor

Figure 2. Lika modular encoder. Source: Lika Electronic

ate moving parts that may contact and cause wear. This further limits the risk of failure due to vibration, shock, mechanical and thermal stresses, and reduces potential machine downtime for maintenance or repair. The kit and modular encoders are also small, lightweight and compact, which enables flexibility and freedom in the motion control system design. These advantages can reduce development time and risk, thereby lowering costs and reducing time-to-market.

About Lika Lab

Lika Lab has a dedicated facility staffed with highly skilled engineers and technicians together with machinery and equipment focused on the design and fabrication of custom encoder products. As a relatively small company of 80 workers, Lika has the flexibility and versatility to produce small volumes of custom encoders, and when an acceptable encoder design has been developed and qualified, the design can be readily transitioned into larger-volume manufacturing. These unique capabilities enable Lika Lab to develop state-of-the-art custom encoders to enable customers to rapidly introduce new products to market. More information on Lika Electronic custom encoder products can be found at the Lika website.