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The purpose of this paper is to highlight the increasing use of rotary or angle encoders and examine two distinct types of non‐contact encoders that employ novel technologies to meet the demands of very different applications.

Firstly, examines the design characteristics of optical angle encoders which are used for precision applications such as rotary format computer‐to‐plate pre‐press machines, machine tool A, B and C axes, and surface mount machines. Then considers magnetic encoder design, including the latest OnAxis™ technology for lower cost applications which require less precision, but are often more physically demanding.

Different rotary motion applications demand different combinations of performance and features to optimise their function – some require accuracy, others repeatability, high‐resolution or low‐cyclic error for velocity loop control, plus cost can also be a key consideration.

There is an increasing need to control rotary motion. An appreciation of the design principles of optical angle and rotary magnetic encoders is necessary to ensure that the correct choice of encoder is made for each application. For an angle encoder system, trade‐offs should be made to determine a realistic specification, and whilst many factors can limit achievable accuracy, techniques are available for reducing any shortfall. For applications where cost constraints and lower accuracy specifications demand a magnetic encoder, robust OnAxis™ sensor technology is gaining acceptance amongst designers, and whilst many of the basic design principles of optical encoders still apply, other specific technical aspects, such as much lower resolution and accuracy must be understood before using these devices. Hidden design costs should also be understood such as installation timings and the environmental suitability of magnets.

Will aid designers of rotary motion systems to make a well‐informed selection of encoder type, based on the detailed needs of their applications, including accuracy and cost budgets.

Details of Electrical and Electronic Apparatus with Applications in the Maintenance and Operation of Aircraft, Missiles and Space Vehicles. These optical incremental encoders have been designed to optimize three basic characteristics ‐ very low price, high resolution, and dependability: low price through design simplifications, high volume production and maximum utilization of high impact moulded plastic components, high resolution (with equivalent accuracy), by computer‐designed optics and in house production and control of discs and masks; dependability, through careful material selection and the application of over 12 years' experience in the design and production of tens of thousands of encoders of a wide variety of types. A wide selection of resolutions can be provided. A binary (powers of two) and a decimal (multiples of 10) series are standard. The units presently being manufactured include a binary 2048 count per turn and a decimal 2000 count per turn. Earlier this year 500, 512, 1000 and 1024 count units were added to the line. Actually any number of direct output counts per turn up to a maximum of 2048 can be obtained on special order and counts as high as 4096 can be produced by electronic doubling of the basic count. This technique requires the use of the quadrature outputs normally furnished in encoders having direction sensing. Outputs from the encoder consist of a counting channel (A), a second counting channel (Q) in quadrature with the (A) channel, and an index marker channel (1) which provides a single pulse per revolution. Encoders arc supplied with any or all of these outputs cither at a low level direct from the photocells or with the outputs amplified and squared by internal electronics.

To describe new technological approaches and improvements to existing methods of measuring position in automation, sports and general applications.

Starts with interesting applications of established sensor technology in motorsports and aircraft manufacture. Then examines some new position sensors based on novel technology.

Optical techniques including lasers and linear encoding enable high precision position sensing over long distances. Laser scanning systems have some advantages over vision systems for pick and place applications. Differential global positioning system (GPS) and carrier‐wave techniques are giving millimeter accuracy to GPSs.

Highlights the more exciting aspects of position sensing.

Intelligent pneumatic actuator (IPA) is a new generation of actuator developed for Research and Development (R&D) purposes in the academic and industrial fields. The purpose of this paper is to show the application of optical encoder and pressure sensor in IPA, to develop a real-time model similar to the existing devices, and to assess the position control performance using a proportional-integrative (PI) controller and a bang-bang controller in real-time.

A micro optical encoder chip is used to detect cylinder rod position by reading constructed laser stripes on a guide rod, whereas a pressure sensor is used to detect the chamber pressure reading. To control the cylinder movements by manipulating pulse-width modulation (PWM) cycles, two unit valves of two ports and two positions were used. A PI controller and a bang-bang controller are used with suitable gain value to drive the valve using PWM to achieve the target actuator position.

The results show the experimental results of the closed-loop position tracking performance of the system using a data acquisition (DAQ) card over MATLAB software.

This paper presents a real-time model used to replace the microcontroller-based system from previous IPA design. The paper proposes two control strategies, PI and bang-bang, to control position using encoder and pressure reading.

This paper presents a micrograting‐based force sensor integrated with a surface micromachined silicon‐nitride probe suitable for characterizing microsurgery force on a single cell or embryo. The probe is supported by springs of a known spring constant, and the surgical penetration force is determined from displacement measurements. The optical‐encoder force sensor exhibits configurable sensitivity and dynamic range, allowing monitoring over a wide range of forces. The periodicity of the encoder response can be used for calibration of the injector displacement and to obtain information about the localized elastic properties of the target. We used a force sensor with a measured spring constant of 1.85 N/m for penetration force measurements on Drosophila embryos, and found a penetration force of 52.5 μN (±13.2 percent) and a membrane displacement of 58 μm (±5.2 percent).

The purpose of this paper is to propose a method to avoid hyperstaticity and eventually reduce the magnitude of undesired force/torques. The authors also study the influence of hyperstaticity on human motor control during a redundant task.

Increasing the level of transparency of robotic interfaces is critical to haptic investigations and applications. This issue is particularly important to robotic structures that mimic the human counterpart's morphology and attach directly to the limb. Problems arise for complex joints such as the wrist, which cannot be accurately matched with a traditional mechanical joint. In such cases, mechanical differences between human and robotic joint cause hyperstaticity (i.e. over-constrained) which, coupled with kinematic misalignment, leads to uncontrolled force/torque at the joint. This paper focusses on the prono-supination (PS) degree of freedom of the forearm. The overall force and torque in the wrist PS rotation is quantified by means of a wrist robot.

A practical solution to avoid hyperstaticity and reduce the level of undesired force/torque in the wrist is presented. This technique is shown to reduce 75 percent of the force and 68 percent of the torque. It is also shown an over-constrained mechanism could alter human motor strategies.

The presented solution could be taken into account in the early phase of design of robots. It could also be applied to modify the fixation points of commercial robots in order to reduce the magnitude of reaction forces and avoid changes in motor strategy during the robotic therapy.

In this paper for the first time the authors study the effect of hyperstaticity on both reaction forces and human motor strategies.

Most of the linear encoders are based on optics. The accuracy and reliability of these encoders are greatly reduced in polluted and noisy environments. Moreover, these encoders have a complex structure and large sensor volume and are thus not suited to small application scenarios and do not have universality. This paper aims to present a new absolute magnetic linear encoder, which has a simple structure, small size and wide application range.

The effect of swing error is analyzed for the sensor structural arrangement. A double-threshold interval algorithm is then proposed to synthesize multiple interval electrical angles into absolute angles and convert them into actual displacement distances.

The final linear encoder measurement range is 15.57 mm, and the resolution reaches ± 2 µm. The effectiveness of the algorithm is demonstrated experimentally.

The linear encoder has good robustness, and high measurement accuracy, which is suitable for industrial production. The linear encoder has been mass-produced and used in an electric power-assisted braking system.

To eliminate the angle deviation of magnetic encoder, this paper aims to propose a compensation method based on permanent magnet synchronous motor (PMSM) sensorless control. The paper also describes the experiments performed to verify the validity of this proposed method.

The proposed method uses PMSM sensorless control method to get high precision virtual angle value, and then get the deviation value between virtual position and magnetic angle which is used as compensation table. Oversampling linear interpolation tabulation method has been proposed to eliminate the noise signals. Finally, a magnetic encoder with precision (repeatability) 0.09° and unidirectional motion precision 0.03 is realized. The control system with an encoder running at 14,000 and 0.01 r/min showing high motion resolution is also realized.

Higher value of current in PMSM leads to a magnetic encoder with higher precision. When using oversampling linear interpolation to tabulate the compensation table, it is understood that more oversampling does not lead to a better result. Finally, validated by experiments, using eight intervals to calculate the mean value of angle deviation leads to the best result.

The angle deviation compensation method proposed in this paper has a great practical implication and a good commercial application. The method proposed in this paper could be effectively used to self-correct the magnetic encoder using arctangent method and also correct any rotary encoder sensor.

This paper originally proposes an adaptive correction method for a rotary encoder based on PMSM sensorless control. To eliminate the noise signals in an angle compensation table, over-sampling linear interpolation tabulation method has been proposed which also guarantees the precision of the compensation table.