Actual Rotation Angle Research Articles

Single-pixel detecting of rotating object using Zernike illumination

In this paper, a single-pixel imaging technique based on Zernike illumination is firstly introduced to detect rotating object. By measuring the specific Zernike moments through a single-pixel detector, the rotation angle of rotating object can be obtained. This method requires only four differential Zernike patterns to illuminate a rotating object in one frame. And the Zernike moments can be calculated from the corresponding reflected intensities collected by the single-pixel detector. Then the rotation angle can be calculated from the phase change of Zernike moments due to the rotation invariant. By theoretical simulation and experimental demonstration, the Zernike moments of the targets are successfully obtained through single-pixel imaging system. The rotation angles are calculated from the measured Zernike moments and agree well with the actual rotation angles. The errors of simulated rotation angle are below 1°. And the RMSEs of the experimental results are below 3° for binary images and below 4° for gray images. The proposed scheme provides a new method for applications on detecting rotating object.

Agricultural machinery photoelectric automatic navigation control system based on back propagation neural network

So as to study the influence of speed factors on the stability of tractor automatic navigation system, combined with neural network control theory, the author proposed a dual-objective joint sliding mode control method based on lateral position deviation and heading angle deviation, using back propagation neural network to establish two-wheel tractor-path dynamics model and straight-line path tracking deviation model, the overall system simulation was carried out by using Matlab/Simulink, and the reliability of the control method was verified. The experimental results showed: when the tractor was tracked with the automatic control of linear path under the condition of the variable speed, the maximum deviation of the lateral position deviation was 12.7cm, and the average absolute deviation was kept within 4.88cm; the maximum deviation of the heading angle deviation was 5°, and the average absolute deviation was kept within 2°; the maximum value of the actual rotation angle was 3.13°, and the standard deviation of the fluctuation was within 0.84°. Under the condition of constant speed and variable speed, using the joint sliding mode control method designed by the author, the dual-objective joint control of lateral position deviation and heading angle deviation could be realized, the controlled overshoot was small, the controlled deviation was small after reaching a stable state, and the adaptability to speed factors was strong, which basically could meet the accuracy requirements of farmland operations.

Deep Deterministic Policy Gradient and Active Disturbance Rejection Controller based coordinated control for gearshift manipulator of driving robot

In order to improve the shift precision of the gearshift manipulator, a coordinated control method for the gearshift manipulator based on the Deep Deterministic Policy Gradient (DDPG) and Active Disturbance Rejection Controller (ADRC) is proposed. Firstly, the kinematic model and dynamics model of the gearshift manipulator are established. Secondly, a coordinated control strategy is proposed to solve the target rotation angle of the servo motor, so as to deal with the nonlinear trajectory problem caused by the mechanical decoupling strategy. Then, an ADRC-based controller and a DDPG-based parameter adjuster are proposed. A DDPG model is established to adaptively adjust the control parameters of ADRC through the target rotation angle, actual rotation angle and rotation angle error. Finally, the theoretical stability proof and experimental verification of the proposed method are conducted. The test results show that the mean absolute error of the proposed method is 34% and 18% lower than that of ADRC and fuzzy PID methods. It shows the effectiveness of the method.

DEVELOPMENT OF A MARKERLESS OPTICAL MOTION CAPTURE SYSTEM BY AN ACTION SPORTS CAMERA FOR RUNNING MOTION

A marker-based optical motion capture system is often used to obtain the kinematics parameters of a running analysis. However, the attached marker could affect the participant's movement, and the system is costly because of the exclusive cameras. Due to its drawbacks, the present research aimed to develop an affordable markerless optical motion capture system for running motion. The proposed system used an action sports camera to acquire the running images of the participant. The images were segmented to get the silhouette of the participant. Then, a human body model was generated to provide a priori information to track participants' segment position. The subsequent procedure was image registration to estimate the pose of the participant's silhouette. The transformation parameters were estimated by particle swarm optimization. The optimization output in the form of the rotation angle of the body segment was then employed to identify right or left lower limbs. To validate the results of the optimization, a manual matching was conducted to obtain the actual rotation angle for all body segments. The correlation coefficient between the rotation angle from image registration and the actual rotation angle was then evaluated. It was found that the lowest correlation coefficient was 0.977 for the left foot. It implies that the accuracy of the developed system in the present work is acceptable. Furthermore, the results of the kinematics analysis have good agreement with the literature. Therefore, the developed system, not only yields acceptable running parameters, but also affordable since it uses an action sports camera and easy to use.

A novel directional object detection method for piled objects using a hybrid region-based convolutional neural network

Digital transformation is an information technology (IT) process that integrates digital information with operating processes. Its introduction to the workplace can promote the development of progressively efficient manufacturing processes, accelerating competition in terms of speed and production capacity. Equipment combined with computer vision has begun to replace manpower in certain industries including manufacturing. However, current object detection methods are unable to identify the actual rotation angle of a specific grasped target while objects are piled. Hence this study proposes a framework based on deep learning that integrates two object detection models. Faster R-CNN (region based convolutional neural network) is utilized to search for the direction reference point of the target, and Mask R-CNN is adopted to obtain the segmentation that not only forms the basis of an area filter but also generates a rotated bounding box by minAreaRect function. After integrating the output from two models, the location and actual rotated angle of target can be obtained. The purpose of this research is to provide the robot arm with the position and angle information of the object located on the top for grasping. An empirical dataset of piled footwear insoles was employed to test the proposed method during the assembly process. Results show that the accuracy of the detection reached 96.26%. The implementation of proposed method in the manufacturing process not only can save man power who responsible for sorting out products but also reduce process time to enlarge production capacity. The proposed method can serve as a part of smart manufacturing system to enhance the enterprise’s competitiveness in the future.

Research on Subdivision System of Sin-Cos Encoder Based on Zero Phase Bandpass Filter.

A novel high-precision subdivision system for high-speed encoders is designed in this work. The system is designed with an arc second of Sin-Cos Encoder (SCE) based on zero phase bandpass filter. The system collects the analog output signals of an encoder with a high-speed data acquisition system (DAS); the noise of a digital signal can be effectively eliminated by zero phase bandpass filter with appropriate prior parameters. Finally, the actual rotation angle of the encoder is calculated by the software subdivision technique in the system. The software subdivision technique includes two methods, which are the Analog Pulse Counter (APC) and the Arc Tangent Subdivision (ATS). The APC method calculates the encoder angle by counting the analog pulses acquired by the arc tangent signal. The ATS method calculates the encoder angle by computing the arc tangent results of each point. The accuracy and stability of the system are first verified with a simulated signal; second, the real signals of an SCE are acquired by a high speed DAS on a test bench of a precision reducer, which is employed in industrial robots. The results of the proposed system are compared. The experimental results show that the system can significantly improve the accuracy of the encoder angle calculation, with controllable costs.

Longitudinal Finger Rotation—Deformation Detection and Correction

Finger vein biometrics is becoming more and more popular. However, longitudinal finger rotation, which can easily occur in practical applications, causes severe problems as the resulting vein structure is deformed in a non-linear way. These problems will become even more important in the future, as finger vein scanners are evolving toward contact-less acquisition. This paper provides a systematic evaluation regarding the influence of longitudinal rotation on the performance of finger vein recognition systems and the degree to which the deformations can be corrected. It presents two novel approaches to correct the longitudinal rotation, one based on the known rotation angle. The second one compensates the rotational deformation by applying a rotation correction in both directions using a pre-defined angle combined with score level fusion and works without any knowledge of the actual rotation angle. During the experiments, the aforementioned approaches and two additional are applied: one correcting the deformations based on an analysis of the geometric shape of the finger and the second one applying an elliptic pattern normalization of the region of interest. The experimental results confirm the negative impact of longitudinal rotation on the recognition performance and prove that its correction noticeably improves the performance again.

Origami Kaleidocycle-Inspired Symmetric Multistable Compliant Mechanisms

Compliant kaleidocycles can be widely used in a variety of applications, including deployable structures, origami structures, and metamorphic robots, due to their unique features of continuous rotatability and multistability. Inspired by origami kaleidocycles, a type of symmetric multistable compliant mechanism with an arbitrary number of units is presented and analyzed in this paper. First, the basic dimension constraints are developed based on mobility analysis using screw theory. Second, the kinematic relationships of the actual rotation angle are obtained. Third, a method to determine the number of stabilities and the position of stable states, including the solution for the parameterized boundaries of stable regions, is developed. Finally, experimental platforms are established, and the validity of the proposed multistable mechanisms is verified.

A novel algorithm for estimating the relative rotation angle of solar azimuth through single-pixel rings from polar coordinate transformation for imaging polarization navigation sensors

Polarized skylight provides navigation compass for many polarization sensitive birds and insects. In this paper, a method based on polar coordinate transformation (PCTA) is proposed to use all the polarization information of the polarization angle image. First, a polar coordinate system is set up on the image of angle of polarization (AOP), and then the single pixel ring corresponding to each pole diameter is extracted. After that, the corresponding point of the same pixel value is found from the two consecutive single pixel rings, and the relative rotation angle of the solar meridian is calculated according to the trigonometric relationship. Finally, simulation and outdoor experiments are performed. The algorithm is preliminarily tested and the accuracy of the simulation is in −0.004°∼+0.045°. The outdoor static experiment is carried out on a roof of a building on campus. The experiment shows that the outdoor static experimental precision is within 0.63°. In order to be applied to the estimation of the actual carrier rotation angle, the dynamic application research experiment is carried out. The center region is chosen as the true value of AOP. The error is about −0.7°∼+0.5°. It proves that the proposed algorithm is effective and accurate.

New Method Based on Improved Double Ball Bar for Measuring Geometric Motion Errors of Coordinate Measuring Machine

In this paper, an optimized method of measuring the geometric motion errors of a coordinate measuring machine (CMM) is proposed. The method is based on an improved double ball bar (DBB) that acquires the motion and link errors of the CMM and its actual rotation angles through simultaneous circular tests. The improved DBB has embedded a ring encoder system to the bottom of a commercial DBB on an auxiliary platform. In addition, an improved motion and link error separation algorithm is established by considering the difference angle Δθ between the actual rotation angle and the theoretical rotation angle of the DBB. Both influential factors of the center offset of the DBB and Δθ are discussed through simulations. When geometric motion errors are compensated for and measured on a 400 mm × 400 mm × 150 mm CMM, the standard deviations of the roundness errors decrease to 1.9 μm and 1.5 μm on the XY and ZX planes, respectively.

Use of Virtual Reality Feedback for Patients with Chronic Neck Pain and Kinesiophobia.

This study examined how individuals with and without neck pain performed exercises under the influence of altered visual feedback in virtual reality. Chronic neck pain (n=9) and asymptomatic (n=10) individuals were recruited for this cross-sectional study. Participants performed head rotations while receiving programmatically manipulated visual feedback from a head-mounted virtual reality display. The main outcome measure was the control-display gain (ratio between actual head rotation angle and visual rotation angle displayed) recorded at the just-noticeable difference. Actual head rotation angles were measured for different gains. Detection of the manipulated visual feedback was affected by gain. The just-noticeable gain for asymptomatic individuals, below and above unity gain, was 0.903 and 1.159, respectively. Head rotation angle decreased or increased 5.45° for every 0.1 increase or decrease in gain, respectively. The just-noticeable gain for chronic pain individuals, below unity gain, was 0.950. The head rotation angle increased 4.29° for every 0.1 decrease in gain. On average, chronic pain individuals reported that neck rotation was feasible for 84% of the unity gain trials, 66% of the individual just-noticeable difference trials, and 50% of the "nudged" just-noticeable difference trials. This research demonstrated that virtual reality may be useful for promoting the desired outcome of increased range of motion in neck rehabilitation exercises by altering visual feedback.

Indoor Intelligent Mobile Robot Localization Using Fuzzy Compensation and Kalman Filter to Fuse the Data of Gyroscope and Magnetometer

This paper develops an indoor intelligent service mobile robot that has multiple functions, can recognize and grip the target object, avoid obstacles, and accurately localize via relative position. The locating method of the robot uses the output values of the sensor module, which includes data from a gyroscope and a magnetometer, to correct the current rotation direction angle of the robot. An angle correction method can be divided into three parts. The first part calculates the angle values obtained from the gyroscope and the magnetometer that are installed on the robot. The second part explores the error characteristics between the sensor module and the actual rotation direction angle of the robot. The third part uses the error characteristic data to design the fuzzy rule base and the Kalman filter to eliminate errors and to get a more accurate orientation angle. These errors can be described as either regular or irregular. The former can be eliminated by fuzzy algorithm compensation, and the latter can be eliminated by the Kalman filter. The contribution of this paper is to propose an error correction method between the calculus rotation angle determined by the sensor and the actual rotation angle of the robot such that the three moving paths, i.e., specified, actual, and calculus paths, have more accurate approximation. The experimental results demonstrate that the combination of fuzzy compensation and the Kalman filter is an accurate correction method.

Hexapod moving in complex terrains via a new adaptive CPG gait design

Purpose – This paper aims to use the Matsuoka’s neural oscillators as the basic units of central pattern generator (CPG), and to offer a new CPG architecture consisting of a dual neural CPG of circular three links responsible for oscillator phase adjustment, to which an external neural oscillator is added, which is responsible for oscillator amplitude adjustment, to control foot depth to balance itself when treading on an obstacle. Design/methodology/approach – It is equipped with a triaxial accelerometer and a triaxial gyroscope to obtain a real-time robot attitude, and to disintegrate the foot tilt in each direction as feedback signals to CPG to restore the robot’ horizontal attitude on an uneven terrain. The CPG controller is a distributed control method, with each foot controller consisting of a group of reciprocally coupling neural oscillators and sensors to generate different locomotion by different coupling patterns. Findings – The experiment results indicated that the gait design method succeeded in enabling a steady hexapod walking on a rugged terrain, the mode of response is such that adjustments can only be made when the tilt occurs. Practical implications – The overall control mechanism uses individual foot tilts as the feedback signal input to the neural oscillators to change the amplitude and compare against the reference oscillators of fixed amplitude to generate the foot height reference signals that can balance the body, and then convert the control signals, through a trajectory generator, to foot trajectories from which the actual rotation angle of servo motors can be obtained through inverse kinematics to achieve the effect of restoring the balance when traveling. Originality/value – The controller design based on the bionic CPG model has the ability to restore its balance when its body tilts. In addition to the model’s ability to control locomotion, from the response waveforms of this experiment, it can also be noticed that it can control the foot depth to balance itself when treading on an obstacle, and it can adapt to a changing environment. When the obstacle is removed, the robot can quickly regain its balance.

Accelerometer-based steering-wheel movement monitoring for drowsy-driving detection

Monitoring steering-wheel movements is a well-documented method of detecting driver fatigue and drowsiness. Current methods for monitoring steering-wheel movements are prohibitive for daily use owing to the high costs of implementation and the necessity for complex modifications to be made to accommodate the new setup. These limitations have confined potentially lifesaving drowsiness detection methods based on steering-wheel movements to laboratory and simulator settings. A new method was proposed in this study, which employed a triaxial accelerometer to provide a cost-effective, easy, and efficacious way to monitor steering-wheel movements without requiring any modifications to the existing vehicle setup. Simulations and experimental results showed that the accelerometer-measured rotation angles of the steering wheel were linearly correlated with the actual rotation angles of the steering wheel registered by the potentiometer ( R2≈1; p < 0.001) and that the steering-wheel movements recorded were also strongly correlated with the actual steering-wheel rotation. The excellent agreement between the accelerometer-estimated steering-wheel rotation and the actual steering-wheel rotation suggests that accelerometers can be a useful tool to monitor the steering-wheel movements for the detection of drowsy driving. Because of its cost-effective nature, the proposed method could help to proliferate the practical deployment of individual drowsy detection.

Normative data on axial rotation of atlanto-occipital joint on 3 Tesla MRI using a simple and reliable method of calculation

Various methods have been used to image and measure the normal range of axial rotation of the atlanto-occipital joint (AOJ), but a simple, precise, and reliable method is needed for everyday practice. To generate normative ranges for AOJ rotation in various in-vivo positions and to investigate the reliability of a simple imaging method for measurement using routine high-field magnetic resonance imaging (MRI). One hundred healthy volunteers were imaged on 3 T MRI with the AOJ in the center of the field of view. The scans were uniformly performed in seven different positions. The range of axial rotation was calculated by the angle between the craniofacial midline and the line linking the anterior and posterior tubercles of the atlas. The angle was defined as positive when it was angled right, and negative when it was angled left. The actual normative range of axial rotation was the difference between the angle in the supine neutral position and in the other positions. The normative axial rotation range of the AOJ in different positions was between -4.8° and +5.0°. The mean values of the actual rotation angles in the right supine position with maximum bending, the right supine position maximum rotation, and the right prostrate position maximum rotation were 0.1°, 1.70°, and 0.8°, respectively. The mean values of actual rotation angles in the left supine position with maximum bending, the left supine position with maximum rotation, and the left prostrate positive with maximum rotation were 0.1°, -1.7°, and -1.1°, respectively. The inter-observer reliability tested. A simple and reliable method of measurement on 3.0 T MRI demonstrated the normative axial rotation range of the AOJ in different positions to be between -4.8° and +5.0° and it was different from zero in neutral rotation. This method could be practically used to precisely diagnose AOJ rotary subluxation or dislocation.

Three-dimensional Kinematic Lumbar Spine Motion Analyses of Trunk Motion During Axial Rotation Activities

An experimental design was conducted to investigate kinematic changes in 3-dimensional trunk motions between subjects with and without chronic low back pain (LBP) while demonstrating axial rotation. The purpose of this study was to compare 3-dimensional kinematic data for the upper and lower thorax and the lumbar spine from the axis of the core spine during axial rotation activities in the standing position while considering anthropometric factors in subjects with and without LBP. Rotation of the trunk is associated with a large number of LBP cases and surrounding spinal tissue injuries. Fifteen subjects with chronic LBP (5 men, 10 women) and 15 subjects without LBP (9 men, 6 women) participated in this study. The outcome measures included kinematic data of actual trunk rotation angles for the upper and lower thorax and the lumbar regions relative to the core spine (spinal root) in sagittal, coronal, and transverse axes. The spinal range of motion was significantly different for each spinal region (F=240.25, P=0.001) and axis (F=213.91, P=0.001). There was a significant interaction between the spinal region and the group (F=4.34, P=0.04). There was also a 3-way interaction with the spinal region, the axis, and the group (F=11.04, P=0.001). These results indicated that spinal region and axes are important to consider because the upper thorax demonstrated a significantly greater rotational displacement in subjects with chronic LBP. Among the anthropometric factors, age (F=6.24, P=0.02) interacted with the spinal region and the axis. Decreased spinal range of motion in older subjects might result in a stiffened spine in addition to possible poor proprioception from back injuries to passive structures in subjects with chronic LBP.

MO‐EE‐A3‐01: Comparison of Prostate Rotation and Calypso Beam Rotation for Prostate Margin Evaluation

Purpose: The Beacon rotation angles reported by the Calypso system have not been utilized clinically due to the difficulties in rotating the patient. The actual prostate rotation angle is affected by Beacons' migration, prostate's shrinkage and deformation due to rectal/bladder filling. This work investigates the actual prostate rotation angles between the planning CT and the treatment CBCT and to compare those reported by the Calypso system. Method and Materials: The Calypso system reports centroid shifts and rotation angles of the 3 implanted Beacons, relative to their locations on the planning CT. CBCT scans were obtained for 9 treatment fractions of 5 patients. The same sets of the Beacons in the planning CT and post‐treatment CBCT were segmented according to their high intensities and aligned according to their centroid positions. An iterative closest point (ICP) method was developed to find the best matching iteratively between two sets of Beacons after rotation and translation. Results: The maximum inter‐Beacon distance varied from 1.1 to 4.7 mm with inter‐Beacon distances from 14.4 to 40.4 mm. The mean Beacon rotation angle reported by the Calypso system in each plane was 4.7±3.8°, which were likely caused by the inter‐Beacon distance change. After the best 3D matching of the Beacons, our method reported a mean rotation angle of 1.5±1.7° for all the fractions. If the projected inter‐Beacon distance was >9mm there was good agreement between our method and the Calypso system. As the inter‐Beacon distance decreased, the uncertainty in the reported rotation angle increased. Conclusion: The actual rotation angles for the prostate were smaller than those for the Beacons reported by the Calypso system. It is recommend to avoid small (<9mm) projected inter‐Beacon distances to reduce the uncertainty in the reported rotation angle.

Real-Time Template Based Face and Iris Detection on Rotated Faces

Real-time iris and face detection on video sequences is important in applications such as study of the eye function, drowsiness detection, man-machine interfaces, face recognition security and multimedia retrieval. In this work, we present a real-time template based method for iris detection in faces with wide coronal (− 40°, + 40°) and transversal (− 45°, + 45°) axis rotations. This method is based on anthropometric templates that were constructed off-line for face coronal and transversal rotation, using face features such as elliptical shape, location of the eyebrows, nose and lips. A line integral is computed using these templates over the fine directional image to find the actual face location, face size and rotation angle. This information provides a region to search for the eyes and the iris boundary is detected. Results computed on five video sequences including coronal and transversal rotations with over 1,700 frames show correct face detection rate of 98.5% and iris detection rate of 94.4%. The method was compared with a “weighting mask method” on two video sequences showing an improved performance. The method was also compared for eye detection to a method using combined binary edge and intensity information in two subsets of the AR face database (63 and 564 images). Different disparity errors were considered and for the smallest error, a 100% correct detection was reached in the AR-63 subset and 99.8% was obtained in the AR-564 subset.

SU‐EE‐A2‐04: Verification of the Rotational Accuracy of the Brainlab Robotics 6D Couch and the ExacTrac X‐Ray 6D Fusion System

Purpose: The Brainlab's Robotics 6D couch is integrated with ExacTrac X‐ray 6D system to compensate the rotational deviations in patient positioning. The purpose of this study is to quantitatively demonstrate the magnitude of improving the rotational accuracy by the 6D system. Method and Materials: Two tests were conducted. A self‐made tool was first used to verify that the rotation angles given by the ExacTrac matched with the actual rotation angles measured by geometry calculation and a level. A wedge was used to raise one side of the test tool for various rotational angles. A Rando head phantom with four BBs implanted was used for the second test. One BB was at the isocenter, with two others 5cm laterally, and the fourth 5cm superior. The relative rotational angles of each BB to the isocenter were calculated from CT images. The phantom was randomly setup within 5° rotations. Portal films were taken after each Robotics 6D couch corrections. BBs positions in the portal films were measured and the rotations were calculated and compared with that in the simulation. Results: The difference between the results determined by X‐ray 6D fusions and actual angels for various setups were 0.113°±0.06° and 0.05°±0.09°, according to level measurement or geometry calculation, respectively, for the pitch direction. The corresponding differences were 0.23°±0.09° and 0.08°±0.09° for the roll. After the Robotics 6D couch correction, the actual rotation was 0.03°±0.05°. and 0.13°±0.04° for the pitch and roll directions. For the second test, the final setup rotation angles compared with the Simulations were 0.42°±0.24°, 0.30°±0.16° and 0.06°±0.02° for pitch, roll and yaw rotations, respectively. Conclusion: The study demonstrated that the rotational accuracy was in the acceptable limit to use in the clinic. This has a great potential to improve the clinical targeting accuracy of radiosurgery.

Mechanical scanning in intravascular ultrasound imaging: artifacts and driving mechanisms:

Objective: Currently, intravascular ultrasound (US) imaging catheters are developed and produced to provide a complementary diagnostic method in the treatment of blood vessel obstructive disease. Typical catheter dimensions are a diameter of 1–2.5 mm and a length of 1–1.5 m. A real-time 360° US scan of the surrounding of a catheter tip can be obtained by mechanical rotation of a US beam, approximately perpendicular to the catheter axis and originating from a single element. It is the purpose of this paper to make the reader aware of the various image artifacts that might occur with flex-shaft mechanical scanning and of the limitations of the technique, and to discuss the possible causes as well as alternative drive mechanisms. Methods: The study is based on definition and discussion of various error mechanisms caused by improper transmission of rotation flex-shaft drives. Adequate ultrasonic imaging implies a one-to-one relationship between the catheter tip scan rotation angle and the angle of polar image line deflection on the display. This can be achieved by applying a predictable, uniform scan rotation at the catheter tip. Deviation from an intentionally uniform scan rotation gives rise to image artifacts, causing either loss of absolute orientation (due to a constant error angle), loss of quality of the real-time aspect (due to a stochastic error angle), or the occurrence of deceptive image distortions (due to a periodic error angle). The magnitude of an acceptable constant tip rotation error (actual tip rotation angle minus expected angle) depends on the need for maintaining an absolute orientation of the image. The stochastic error should be kept to a minimum: random misplacement of image lines in the order of degrees already is disturbing to the interpretation of the image. As a practical arbitrary criterion for the periodic error angle, a maximum peak-to-peak value of 20° can be defined. Results: Catheter tip driving mechanisms have to be evaluated, considering their potential to maintain a predictable (often uniform) catheter tip scan rotation. A 0.8 mm OD double-layer spiral type flexible drive-shaft has been developed, which meets the requirements, exhibiting a bending rigidity of 1.5 Nmm 2 and a torsional rigidity of more than 100 Nmm 2. This drive-shaft shows a sensitivity to influences, inducing rotation error angles, like pre-curvature of the shaft and friction, of about 1% compared to a simple wire of e.g. stainless steel. Conclusion: For practical purposes, today's technologies in the production of flex-shafts have improved and these devices can be very usefully applied in clinical situations. Flex-shaft problems can be avoided if, alternatively, rotation power could be provided in the catheter tip itself. To this effect, an electromagnetic micromotor has been developed, with a diameter of 1 mm, exhibiting adequate running behaviour. Implementation of this motor in a catheter tip is in progress.