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This article describes the design and fabrication of an angle tilt adjustment device that automatically adjusts the measured surface to parallel the surface plate. The device features a 150 mm × 150 mm worktable and enables independent tilt adjustment of the worktable surface in the X and Y directions via two worm-gear pairs driven by stepper motors. For high angular resolution around the OX and OY axes, the device employs a transmission ratio of 6781 from two motors to these axes. The experimental results reveal that the adjusted average nonparallelism between the measured surface and the surface plate reaches 0.001 mm. The results indicate that the device is fully capable of performing accurate measurements. The device is compact, easy to carry, and low in production cost, making it ideal for installation in small and medium mechanical workshops. [ABSTRACT FROM AUTHOR]

This study presents a methodology used in the design development of stepper motors. The methodology unites virtual and physical techniques to assess the structure under development at its various design stages. Virtual prototyping is used twice, at the concept and early design stages. Concept check aims to give more general directions for further design development. In contrast, the simulations at the detailed design stage allow for assessing various design parameters at a high level of confidence. The testing of a physical prototype is used to validate simulation results. It is also used to check the design just before it is finished. The presented methodology is demonstrated in an industrial use case for stepper motor development for hydraulic valve application. The main contribution of this study is related to the way the combination of virtual and physical prototyping and testing at different product development stages applies to the development of stepper motors and other similar products. [ABSTRACT FROM AUTHOR]

Programming RRR-type serial arm robots, especially for pick-and-place tasks, is timeconsuming and intricate, often requiring the robots' temporary removal from service for programming and testing. This study proposes a haptic interface replicating the mechanical structure of RRR-type robots, integrating position sensors and stepper motors at each joint. This interface communicates with a virtual environment governed by the robot's mathematical model and task space data, allowing users to intuitively manipulate the virtual robot and record trajectories. Operational safety is ensured through joint locking to prevent collisions and avoid singular points. Comparative evaluations show significant reductions in computation time and enhanced learning efficiency compared to traditional methods. The evaluation includes measuring task completion times, demonstrates faster task accomplishment with the haptic interface. Beyond streamlining robotic arm programming, the approach prioritizes user-friendliness and operational efficiency, validated through experiments on both lab platforms and real robots. Additionally, the System Usability Scale (SUS) was employed to assess user satisfaction, with results indicating high user approval. These findings underscore the effectiveness of the haptic interface in advancing robotic trajectory learning and its potential for broader applications in robotics research and development. [ABSTRACT FROM AUTHOR]

Copyright of Buletinul AGIR is the property of Asociatia Generala a Inginerilor din Romania and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents a stepper motor drive using the hybrid two-phase model. The stepper motor changes the pulse signals into angular displacement with some angles. Stepper motors are used to control the speed and are also more reliable for smooth operations. The stepper motor provides constant holding torque with controlled speed ranges from 0 to 6000 range. The closed-loop control technique with park transformation is used to control the speed torque variables in a design range. The simulation and hardware results were discussed in MATLAB\Simulink software. The verified simulation results are motor source voltage, motor source current, motor speed, and torque. The hardware results are also implemented in this paper, the implemented circuit by using Arduino microcontroller. [ABSTRACT FROM AUTHOR]

In the present paper, the use of programmable microprocessors to develop a computerized stand for the preparation of a mixture of flammable/toxic/explosive gases in order to obtain mixtures at concentrations in explosive range is presented. The operating principle of the stand is based on the mixing of two volumetric flows, controlled with the help of microprocessors, where gases are stored and circulated at atmospheric pressure through cylindrical injectors, driven by stepper motors so that the gas circuit does not require valves. The exit of the stand is a homogenization chamber, with agitator and sensor to confirm the desired concentration of the mixture. This automated stand eliminates mechanical, electric or pneumatic valves from the gas circuits, avoiding elements with high mechanical resistance suitable for high pressures/depressions, removing the possibility of the return of the gas flow, without sensitivity to sudden pressures variations. [ABSTRACT FROM AUTHOR]

In the present paper, the use of programmable microprocessors to develop a computerized stand for the preparation of a mixture of flammable/toxic/explosive gases in order to obtain mixtures at concentrations in explosive range is presented. The operating principle of the stand is based on the mixing of two volumetric flows, controlled with the help of microprocessors, where gases are stored and circulated at atmospheric pressure through cylindrical injectors, driven by stepper motors so that the gas circuit does not require valves. The exit of the stand is a homogenization chamber, with agitator and sensor to confirm the desired concentration of the mixture. This automated stand eliminates mechanical, electric or pneumatic valves from the gas circuits, avoiding elements with high mechanical resistance suitable for high pressures/depressions, removing the possibility of the return of the gas flow, without sensitivity to sudden pressures variations.

Introduction: Phantoms mimicking tissue motion have become a valuable tool for quality control in various fields of medical physics including lung phantoms for image-guided radiotherapy and functional imaging in nuclear medicine or magnetic resonance imaging (MRI) in the body. In MRI, precise kinematic models are more difficult to realize owing to the requirements of MRcompatibility. Pneumatic stepper motors built entirely of non-conducting materials can be safely used in an MR environment, with pressurized air supply and switching residing outside the magnet room. Methods: In this research, a torso phantom was built adopting a 3D-printed linear stepper drive for use with high-field MR scanners. It was possible to simulate respiratory motion of a 3D-printed left ventricle phantom using the stepper. Results and discussion: Precise and accurate motion for a time of 15 min over a range of 8 cm were achieved with speeds up to 5.5 mm/s when the stepper was loaded with the left ventricle phantom. It was shown that the motor is an effective tool for quality control in multi-modal medical imaging. [ABSTRACT FROM AUTHOR]

To achieve cost-effective micro-/nano-displacement adjustment, this paper integrates the advantages of flexible hinge micro-/nano-displacement transmission. A linear stepper motor is utilized as the driving component to design and develop a high-precision, low-cost micro-/nano-positioning system. The structure, design, and working principles of the micro-/nano-positioning platform are introduced. The scaling factor model between micro-positioning platforms and nano-positioning platforms is analyzed. Static and dynamic models of flexible mechanisms have been established. The dimensions of the mechanical structure and the selection of motors are determined. The mechanical characteristics of the micro-/nano-positioning platform are validated through finite element analysis. To address the characteristic of increasing loads during the transmission process, an intelligent control system based on current feedback is designed and developed. The integration of drive and control provides a high level of system integration. Finally, experimental calibration was conducted to test the motion characteristics of the linear stepper motor-driven micro-/nano-positioning platform. It achieved a minimum displacement control resolution of 100 nm and demonstrated a certain level of stability. [ABSTRACT FROM AUTHOR]

Introduction/purpose: SMART orthopedic systems use fixators with remote monitoring, processing, and communication capabilities to leverage healing progression data for personalized, real-time monitoring of a healing process. The fixators incorporate small and compact piezoelectric sensors that generate electrical signals upon the application of force to the piezoelectric diaphragm. This enables doctors to remotely guide fixation devices using indirectly and remotely controlled stepper motors known for their precision and accuracy. Reliability of stepper motors makes them a viable alternative for the mechanical tools traditionally used by doctors for fixator extension. Methods: This study focuses on the evaluation of sensor-based technology in orthopedic applications. The paper presents a theoretical framework for the application of SMART devices in the bone fracture healing process. It delves into the structure and functionality of piezoelectric transducers, offering a comprehensive insight into this technology and various engineering aspects of SMART systems. Results: The implementation of SMART systems has significantly enhanced doctor-patient communication. This improvement is facilitated through a dual-phase process involving gathering, processing, and transmitting the data wirelessly from the patient's (sensor) interface to the doctor who uses specialized software for data analysis and wireless transmission to the stepper motor actuator. Subsequently, the data is forwarded to the decoder at the motor site, where a motor controller generates the control signal for the stepper motor driver. Conclusion: SMART implants can provide doctors with quantitative data that can be used in directing a rehabilitation plan. The sensor-based technology offers insights into the stress induced by the callus formation enabling bidirectional communication between the doctor and the patient. The stepper motor is a tool that aids in personalized treatment from the distance.

This study presents a methodology used in the design development of stepper motors. The methodology unites virtual and physical techniques to assess the structure under development at its various design stages. Virtual prototyping is used twice, at the concept and early design stages. Concept check aims to give more general directions for further design development. In contrast, the simulations at the detailed design stage allow for assessing various design parameters at a high level of confidence. The testing of a physical prototype is used to validate simulation results. It is also used to check the design just before it is finished. The presented methodology is demonstrated in an industrial use case for stepper motor development for hydraulic valve application. The main contribution of this study is related to the way the combination of virtual and physical prototyping and testing at different product development stages applies to the development of stepper motors and other similar products.

The performance of the extended state observer (ESO) in an Active Disturbance Rejection Control (ADRC) is limited by the operational load in stepper motor control, which has high real-time requirements and may cause delays. Additionally, the complexity of parameter tuning, especially in high-order systems, further limits the ESO's performance. This paper proposes a composite ADRC (LTDRO-ADRC) based on a load torque dimensionality reduction observer (LTDRO). Firstly, the LTDRO is designed to estimate abrupt load disturbances that are difficult to compensate for using the ESO. Secondly, the transfer function under the double-closed loop is deduced. Additionally, the LTDRO uses a magnetic encoder to gather the system state and calculate the load torque. It then outputs a compensating current feedforward to the current loop input. This method reduces the delay and complexity of the ESO, improving the response speed of the ADRC speed ring and the overall response of the system to load changes. Simulation and experimental results demonstrate that it significantly enhances dynamic control performance and steady-state errors. LTDRO-ADRC can stabilize the speed again within 49 ms and 17 ms, respectively, in the face of sudden load increase and sudden load removal. At the same time, in terms of steady-state error, compared with ADRC and CADRC, they have increased by 94% and 88%, respectively. In terms of zero-speed starting motors, the response speed is increased by 58% compared to a traditional ADRC. [ABSTRACT FROM AUTHOR]

Copyright of Military Technical Courier / Vojnotehnicki Glasnik is the property of Military Technical Courier / Vojnotehnicki Glasnik and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Electronic medical development focuses on creating an efficient rehabilitation device that will strengthen all surrounding muscles and enhance elbow performance. The elbow rehabilitation tool (ERT) provides sophisticated methods like exercise and motion analysis. The initiative is notable for its advanced assessment methods and adaptable training curricula, which offer users a thorough and successful therapeutic experience. The ERT includes elements like a stepper motor, variable resistor, steel wire, microcontroller, motor driver, and components created using a 3D printer. The experiment results show that the average systematic error percentage is about 82.857%, where seven healthy people have tested the ERT aged between 22 and 55 (five males and two females). The ERT also has achievement evaluation, which improves motivation and dedication to the recovery methods through an effective rehabilitation experience for users.

IntroductionPhantoms mimicking tissue motion have become a valuable tool for quality control in various fields of medical physics including lung phantoms for image-guided radiotherapy and functional imaging in nuclear medicine or magnetic resonance imaging (MRI) in the body. In MRI, precise kinematic models are more difficult to realize owing to the requirements of MR-compatibility. Pneumatic stepper motors built entirely of non-conducting materials can be safely used in an MR environment, with pressurized air supply and switching residing outside the magnet room.MethodsIn this research, a torso phantom was built adopting a 3D-printed linear stepper drive for use with high-field MR scanners. It was possible to simulate respiratory motion of a 3D-printed left ventricle phantom using the stepper.Results and discussionPrecise and accurate motion for a time of 15 min over a range of 8 cm were achieved with speeds up to 5.5 mm/s when the stepper was loaded with the left ventricle phantom. It was shown that the motor is an effective tool for quality control in multi-modal medical imaging.

The main topic of this paper is how to develop pick and place delta robot with high efficiency mechanical parts and prosaically assemble it, additionally built electrical wiring diagram all of this supported by vision computer system. The system has a low-cost part and solves many problems to build this robot. Electrical section has two main components master and slave the master is raspberry pi and slave is Arduino, master is used to vision detect object and Arduino is used to invers kinematics equation, move motors to target position, control in hydraulic system to pull the object with suction cup. The process of vison system is passing through some steps, detect the object by color range, contouring box then send the real position to an Arduino. The experimental process proved the effectiveness and accuracy of the delta robot vision system in the sorting process from conveyor system. The target of system that function is applied with a low cost.

The utilization of closed-loop control in stepper motors has become prevalent in scenarios requiring high-precision control. In this paper, classical proportional-integral (PI) and sliding mode control (SMC) are combined, and a compound control strategy based on the vector closed-loop control of stepper motors is proposed. The primary advantage of this approach is its ability to harness the precision of PI control and the robustness of SMC, mitigating the limitations of each method when used independently. A key innovation is the introduction of an automatic weight adjustment mechanism, which allows adaptive modulation of the two control strategies based on varying operating conditions, ensuring that the two algorithms work together in a coordinated manner. Simple fuzzy logic is implemented for automatic weight adjustments, and a smoothing mechanism is incorporated to prevent instability arising from swift weight adjustments. Simulations were conducted using MATLAB/Simulink to distinctly assess the speed and position control of stepper motors and compare them with those of individual PIs, SMCs, and adaptive network-based fuzzy inference system intelligent controllers. The results indicate that the compound control demonstrates a swifter speed response, a diminished steady-state error, and robust anti-interference capabilities. These results confirm the effectiveness of the compound control strategy in applications where both precision and robustness are paramount.

Copyright of Large Electric Machine & Hydraulic Turbine is the property of Large Electric Machine & Hydraulic Turbine Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of EMERG: Energy. Environment. Efficiency. Resources. Globalization is the property of Romanian National Committee of World Energy Council and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper introduces a model-based control scheme for controlling the position of a suspended cable-driven parallel robot. The robot is designed to have a fixed frame base with four cables. The cables are attached to winches on one end, driven by stepper motors, and to a moving platform at the other end. The control scheme consists of two systems: the reference model and the implemented control. The implemented control hosts the stepper motor to drive the winch based on the requirements derived from the reference model. The reference model converts the desired Cartesian trajectory into joint spaces, which are then translated into the number of required steps. The number of steps will act as a set point for the stepper motor. Three trajectories are generated to test the compliance of the controller with its position. The error compensation scheme is introduced to increase the positional accuracy of the previous controller, especially on the z-axis. This algorithm uses the nature of discrete stepper motor movement to estimate the actual cable length, which is then fed back to the control system as an error. The control simulation results indicate a significant improvement in control performance, i.e. reduced position error, was achieved.

To achieve cost-effective micro-/nano-displacement adjustment, this paper integrates the advantages of flexible hinge micro-/nano-displacement transmission. A linear stepper motor is utilized as the driving component to design and develop a high-precision, low-cost micro-/nano-positioning system. The structure, design, and working principles of the micro-/nano-positioning platform are introduced. The scaling factor model between micro-positioning platforms and nano-positioning platforms is analyzed. Static and dynamic models of flexible mechanisms have been established. The dimensions of the mechanical structure and the selection of motors are determined. The mechanical characteristics of the micro-/nano-positioning platform are validated through finite element analysis. To address the characteristic of increasing loads during the transmission process, an intelligent control system based on current feedback is designed and developed. The integration of drive and control provides a high level of system integration. Finally, experimental calibration was conducted to test the motion characteristics of the linear stepper motor-driven micro-/nano-positioning platform. It achieved a minimum displacement control resolution of 100 nm and demonstrated a certain level of stability.

In this study a four-wheel independent steering (4WIS) system for an electric vehicle (EV) steered by stepper motors is presented as a revolutionary real-time control technique employing neural networks in combination with fuzzy logic, where the use of the neural network greatly simplifies the computational process of fuzzy logic. The control of the four wheels is based on a variation of a Hopfield Neural Network (VHNN) method, in which the input is the error of each steering motor and the output is processed by a hyperbolic tangent function (HTF) feeding the fuzzy logic controller (FLC), which ultimately drives the stepper motor. The whole system consists of the four aforementioned blocks which work in sync and are inseparable from each other with the common goal of driving all the steering stepper motors at the same time. The novelty of this system is that each wheel monitors the condition of the others, so even in the case of the failure of one wheel, the vehicle does not veer off course. The results of the simulation show that the suggested control system is very resilient and workable at all angles and speeds. [ABSTRACT FROM AUTHOR]

The Delta robot is a parallel robot that is over-actuated and has a highly nonlinear dynamic model, which poses a significant challenge to its control design. The inverse kinematics that maps the motor angles to the position of the end effector is highly nonlinear and extremely important for the control design of the Delta robot. It has been experimentally shown that geometry-based inverse kinematics is not accurate enough to capture the dynamics of the Delta robot due to manufacturing component errors, measurement errors, joint flexibility, backlash, friction, etc. To address this issue, we propose a neural network model to approximate the inverse kinematics of the Delta robot with stepper motors. The neural network model is trained with randomly sampled experimental data and implemented on the hardware in an open-loop control for trajectory tracking. Extensive experimental results show that the neural network model achieves excellent performance in terms of the trajectory tracking of the Delta robot under different operation conditions, and outperforms the geometry-based inverse kinematics model. A critical numerical observation indicates that neural networks trained with the specific trajectory data fall short of anticipated performance due to a lack of data. Conversely, neural networks trained on random experimental data capture the rich dynamics of the Delta robot and are quite robust to model uncertainties compared to geometry-based inverse kinematics. [ABSTRACT FROM AUTHOR]

Fruit sorting determines market value. Farmers and traders commonly use physical-eye inspection and handpicking for sorting, but this is labour-intensive and ineffective. This research work aims to develop a sensor-based automated system for sorting freshly harvested tomato fruits. The automated system sorts tomato fruits into small, medium, and big sizes for market value. To evaluate the system performance, 115 fruits were machine-sorted and compared to eyeinspection and physical measurement. Physical measurement was done by measuring the minor, intermediate, and major diameters of each fruit with a Vernier calliper. While the eye-inspection was carried out by manual human examination with the eye. Results show average percentage error between physical measurement and automated sorting is 10.264%, which implies 89.736% accuracy. The influence of conveyor speed at three levels (2.8, 3.4, and 3.9) cm sec-1 on overall system performance was evaluated, and the optimum speed of 3.4 cm sec-1 was obtained. [ABSTRACT FROM AUTHOR]

In this paper, we develop a low-cost delta robot arm for grasping objects of unspecified size thanks to a vision system. Stepper motors are used instead of ac servo motors to build a low-cost delta robot arm. Furthermore, we use available materials and machining methods such as laser cutting and 3d printing instead of CNC milling and turning to reduce fabrication costs. The controller is based on a low-cost embedded controller - Arduino Uno for controlling the robot's motion. The vision system is constructed to determine the 3D coordinate of objects in the workspace as well as the sizes of objects. The gripper is opened with a distance of two fingers equal to the size of the objects, and the robot is controlled to the objects' coordinates to grasp them. An application to pick up objects on a conveyor belt is developed to validate the design. The experimental results show that the robot system works correctly, the robot arm moves smoothly, and the information determined by the vision system has a small error, ensuring that the robot can accurately pick up products.

Generally, the position closed-loop control of stepper motors requires high-precision models, however stepper motors are complex nonlinear systems, and high-precision models are difficult to obtain. In order to solve this problem, a variable frequency controller based on hyperbolic tangent function is proposed. Similar to the proportional integral (PI) control method, this method does not require an exact model of the plant. The experimental results show that when tracking the sinusoidal signal ${180^ \circ }\sin (0.628t)$ , the tracking error of the Tanh control algorithm is reduced by nearly 60% compared with the PI control algorithm, which provides a new idea for the position closed-loop control of stepper motor.

Peristaltic pumps (PPs) are used to pump clean/sterile or exceptionally responsive liquids without tainting them. They are used in haemodialysis and heart-lung machines to circulate blood as a sidestep during medical procedures. The purpose of this research is to design and construct a PP which consists of a three-roller pump, a bubble sensor, a motor drive, a stepper motor, a microcontroller, and a safety unit. The safety unit functions by using the air bubble sensor, which stops the motor in case of bubble insertion. The performance is experimentally tested in terms of average sensitivity, specificity, and accuracy, which are 99%, 99.55%, and 99.33%, respectively. The evaluation is based on the classification models of true positive (TP), false positive (FP), true negative (TN), and false negative (FN). The overall accuracy is about 98.9%, which indicates the high efficiency of the constructed mechanism.

3D printing is a process in which material is joined layer by layer under computer control to make a 3D object easy to get almost any shape. This technology finds applications in various fields and it is attracting considerable interest from industry and academia. There are many different brands and models of motors used in 3D printers, and they all vary in quality and effectiveness. In this article we present the principal of the 3D printer, types of motors used in 3D printer and mathematical modelling of this motors like brushless direct current (DC) motor, permanent magnet synchronous motor (PMSM), and stepper motor. The models of analytical equations describing the three systems of motors are evaluated and developed by Matlab/Simunlink. In this paper, we have conducted a comparison of the series of results from simulation between the performance of PMSM, brushless DC and stepper motor. Among several criteria, this simulation study allows to select the criterion of response time to reach the desired speed and the precision of the rotor position to choose the most performant motor for 3D printers. [ABSTRACT FROM AUTHOR]

This paper presents the design and analysis of a modified double-ended forward converter (DEFC) for stepper motor-based robotic applications. The proposed converter topology provides galvanic isolation between the input and output while also higher efficiency with a smooth operative system, making it suitable for use in robotic systems that require both power and control signals to be transmitted. The paper also discusses the control strategy for the converter, which uses Proportional Integral (PI) to regulate the output voltage and current. The control strategy is implemented using a microcontroller-based system, which provides precise control of the output parameters. The converter is tested using a stepper motor-based load, and the results demonstrate the effectiveness of the proposed topology and control strategy. In addition to the experimental results, the paper also presents a detailed analysis of the converter's performance. The analysis includes the input voltage and current, capacitor voltage, MOSFET parameters, output voltage and current, and calculation of efficiency. The analysis results show that the proposed converter topology and control strategy offer high efficiency comparing to existing converting approaches. Overall, the proposed double-ended forward converter offers a suitable solution for stepper motor-based robotic applications, providing efficient and reliable power and control signals. The results demonstrate the effectiveness of the proposed converter topology and control strategy, making it a promising option for use in future robotic systems. [ABSTRACT FROM AUTHOR]

A review of methods for adaptive neural network control of actuators based on a stepper motor is presented. A model of a universal mechatronic module with a stepper motor is defined. The investigated field-oriented classical proportional-integral-derivative, neural network radial basis, and neural network sigmoidal adaptive motor control algorithms are described. The results of modeling the digital control system for the universal mechatronic module at nominal parameters and under the influence of parametric and functional uncertainties are demonstrated. [ABSTRACT FROM AUTHOR]

With the increase in the aging population, the demand for healthcare devices has increased. Among the aging population, many experience joint pain, muscle weakness, or poor balance. Without external help, such persons may have difficulty walking, fall easily, or experience poor quality of life. To provide this category of the population with the opportunity to exercise and walk safely and take care of themselves in daily activities, a stepper motor-powered walking assistive device is proposed and built. The device enables users with different heights to walk in suitable gaits; assists users to stand up, sit down, and step up or down stairs; automatically detects user's intention using pressure sensors and potentiometers; and can be used outdoors for long periods. In this study, the effectiveness of the device is verified using muscle-activity measurements. [ABSTRACT FROM AUTHOR]

This paper introduces a model-based control scheme for controlling the position of a suspended cable-driven parallel robot. The robot is designed to have a fixed frame base with four cables. The cables are attached to winches on one end, driven by stepper motors, and to a moving platform at the other end. The control scheme consists of two systems: the reference model and the implemented control. The implemented control hosts the stepper motor to drive the winch based on the requirements derived from the reference model. The reference model converts the desired Cartesian trajectory into joint spaces, which are then translated into the number of required steps. The number of steps will act as a set point for the stepper motor. Three trajectories are generated to test the compliance of the controller with its position. The error compensation scheme is introduced to increase the positional accuracy of the previous controller, especially on the z-axis. This algorithm uses the nature of discrete stepper motor movement to estimate the actual cable length, which is then fed back to the control system as an error. The control simulation results indicate a significant improvement in control performance, i.e. reduced position error, was achieved. [ABSTRACT FROM AUTHOR]