Motion Tracking Control Research Articles

Dynamic modeling and terminal sliding mode control of a 3-DOF redundantly actuated parallel platform

An improved 3-degrees-of-freedom (DOF) redundantly actuated parallel platform (RAPP) has been designed to adjust the pose of heavy-loaded and large-scaled equipment. This paper presents the dynamic modeling and controller designing of the 3-DOF parallel mechanism. According to the specific structure and characteristics, the proposed mechanism is considered as a multibody system, whose dynamic model is formulated via Lagrange's Equations. On the foundation of dynamics analysis, a control strategy based on the terminal sliding mode is presented to achieve precise motion tracking control. The simulation results indicate that the designed controller not only makes an improvement on the trajectory tracking ability, but also enhances the robustness under constantly changing parameters and disturbance. Experiments are also conducted on the pose adjustment prototype system to validate the RAPP's performance and assess the control method.

Predictor-Based Motion Tracking Control for Cloud Robotic Systems with Delayed Measurements

This paper addresses the problem of motion prediction and tracking control for cloud robotic systems with time-varying delays in measurements. A novel method using an observer-based structure for position and velocity prediction is developed to estimate the real-time information of robot manipulator. The prediction error can converge to zero even if model uncertainties exist in the robot manipulator. Based on the predicted positions and velocities, some sufficient conditions are derived to design suitable tracking controllers such that semi-globally uniformly ultimately bounded tracking performance of the predictor–controller couple can be guaranteed. Finally, the effectiveness and robustness to model uncertainties of the proposed method are verified by a two degree-of-freedom (DOF) robot system.

Energy efficiency improvement of heavy-load mobile hydraulic manipulator with electronically tunable operating modes

The conventional hydraulic drive system for a heavy-load mobile manipulator is usually operated under single mode, such that both inlet/outlet and potential energy losses are large to lower the energy efficiency. In this paper, a novel electro-hydraulic drive system is presented to improve energy efficiency. Extended control degrees of freedom are obtained utilizing the independent metering valve and electronic controlled pump. Then, multiple operating modes are carried out pertaining to the cylinder, valve, and pump. To achieve both optimal energy efficiency and precise motion tracking, both multi-mode switching and multi-variable controller are designed to accommodate with time-varying and uncertain load characteristics. As a consequence, the inlet, outlet, and potential energy losses can be decreased simultaneously. The experimental validation is conducted by using a three-joint manipulator in a 2 t excavator. A duty cycle of movement including all three actuators and covering full load quadrants is used to evaluate the efficiency improvement. Compared with the conventional load sensing system, the proposed multi-mode switching system using the pump pressure with valve meter-in control mode yields a 25.8% energy-saving ratio. Furthermore, the pump flow with valve mete-out control mode yields a 35.3% energy-saving ratio. Using this combined control mode, higher efficiency can be obtained due to the minimum inlet losses, but faster dynamic response together with higher overshoot will appear. It is proved that the energy efficiency is improved, while the motion tracking performance is not degraded by introducing the multi-mode switching.

Design of motion trajectory and tracking control for underactuated cart‐pendulum system

SummaryA cart‐pendulum system is a nonlinear underactuated mechanical system with two degrees of freedom. This paper addresses the motion trajectory design and tracking control problems for this underactuated system. First, a friction‐like control law is designed for the system. Then, the characteristics of the closed‐loop control system are analyzed. Second, a new method of constructing an optimal trajectory for the system is developed. Then, a tracking control law is designed to quickly track the constructed trajectory. It guarantees that the motion control of the cart‐pendulum system is achieved along a reference trajectory. Finally, a numerical example is presented to demonstrate the effectiveness of the theoretical results. This study constructs an optimal trajectory for the cart‐pendulum system in its whole motion space and solves the motion control objective by tracking the constructed trajectory. It has many advantages compared with other motion control methods, eg, the optimal motion control objective of the system is achieved by a single control law; and the motion process and transient characteristics (eg, the settling time) of the control system can be accurately predicted.

Energy-efficient and high-precision control of hydraulic robots

In addition to high-precision closed-loop control performance, energy efficiency is another vital characteristic in field-robotic hydraulic systems as energy source(s) must be carried on board in limited space. This study proposes an energy-efficient and high-precision closed-loop controller for the highly nonlinear hydraulic robotic manipulators. The proposed method is twofold: 1) A possibility for energy consumption reduction is realized by using a separate meter-in separate meter-out (SMISMO) control set-up, enabling an independent metering (pressure control) of each chamber in hydraulic actuators. 2) A novel subsystem-dynamics-based and modular controller is designed for the system actuators, and it is integrated to the previously designed state-of-the-art controller for multiple degrees-of-freedom (n-DOF) manipulators. Stability of the overall controller is rigorously proven. The comparative experiments with a three-DOF redundant hydraulic robotic manipulator (with a payload of 475 kg) demonstrate that: 1) It is possible to design the triple objective of high-precision piston position, piston force and chamber pressure trackings for the hydraulic actuators. 2) In relation to the previous SMISMO-control methods, unprecedented motion and chamber pressure tracking performances are reported. 3) In comparison to the state-of-the-art motion tracking controller with a conventional energy-inefficient servovalve control, the actuators’ energy consumption is reduced by 45% without noticeable motion control (position-tracking) deterioration.

A unified symplectic pseudospectral method for motion planning and tracking control of 3D underactuated overhead cranes

SummaryIn this paper, a unified symplectic pseudospectral method for motion planning and tracking control of 3D underactuated overhead cranes is proposed. A feasible reference trajectory taking constraints into consideration is first generated offline by the symplectic pseudospectral optimal control method. Then, a trajectory tracking model predictive controller also based on the symplectic pseudospectral method is developed to track the reference trajectory. At each sampling instant, the trajectory tracking controller works by solving an open‐loop optimal control problem where linearized system dynamics is used instead to improve the computational efficiency. Since the symplectic pseudospectral optimal control method is the core algorithm for both offline trajectory planning and online trajectory tracking, constraints on state variables and control inputs can be easily imposed and hence theoretically guaranteed in solutions. By selecting proper weighted matrices on tracking error and control, the developed controller could achieve control objectives in both accurate trolley positioning and fast suppressing of residual swing angles. Simulations for 3D overhead crane systems in the presence of perturbations in initial conditions, an abrupt variation of system parameter, and various external disturbances demonstrate that the developed controller is robust and of excellent control performance.

Adaptive sliding mode enhanced disturbance observer-based control of surgical device

This paper presents an enhanced adaptive robust disturbance observer-based motion tracking control methodology. This control approach is established and investigated for a semi-automated hand-held ear surgical device for the treatment of Otitis Media with Effusion. The proposed control methodology is utilised for tracking a desired motion trajectory in the presence of unknown or uncertain system parameters, nonlinearities including hysteresis, and disturbances in the motion system. The stability of the control approach is analysed. The convergence of position and velocity tracking errors is proven theoretically. A precise tracking performance following desired motion trajectory is demonstrated in the experimental study.

Particle swarm optimization-tuned adaptive fuzzy output feedback motion tracking control of piezo-positioning mechanism with unknown hysteresis

This paper considers the problem of observer-based adaptive fuzzy output feedback control for a piezo-positioning mechanism with unknown hysteresis. In this paper, fuzzy logic systems (FLSs) are used to estimate the unknown nonlinear functions, and also Nussbaum function is utilized to overcome the unknown direction hysteresis. Based on the Lyapunov method, the control scheme is constructed by using the backstepping and adaptive technique. In order to better control performance in reducing tracking error, the particle swarm optimization (PSO) algorithm is utilized for tuning the controller parameters. Proposed adaptive controller guarantees that all the closed-loop signals are semiglobally uniformly ultimately bounded (SGUUB) and the tracking error can converge to a small neighborhood of the origin. Finally, the simulation results are provided to demonstrate the effectiveness and robustness of the proposed approach.

Enhanced backstepping sliding mode controller for motion tracking of a nonlinear 2-DOF piezo-actuated micromanipulation system

In this paper a robust backstepping sliding mode controller is developed for tracking control of 2-DOF piezo-actuated micromanipulation system. The control approach is established to obtain high precision tracking in the existence of hysteresis nonlinearity, model uncertainties and external disturbances which treated as a lumped uncertainty. The control scheme is developed based on backstepping technique and a sliding surface is introduced in the final stage of the algorithm. To attenuate the chattering problem caused by a discontinuous switching function, a simple fuzzy system is used. The asymptotical stability of the system can be guaranteed since the control law is derived based on Lyapunov theorem. The effectiveness and feasibility of the suggested approach are tested for tracking of a micrometer-level reference trajectories. From the results, it is shown that the developed control system not only achieves satisfactory control performance, but also eliminates the chattering phenomena in the control effort.

Motion planning and tracking control for coupled flexible beam structures

A systematic flatness-based motion planning approach for a structure consisting of coupled flexible bending beams is introduced. The beams are equipped with in-domain piezoelectric macro-fiber composite (MFC) actuators and are coupled by an elastic string, modeled as spring, which connects the tip masses of adjacent beams. This setup provides a challenging benchmark experiment to evaluate control concepts. Hamilton’s principle leads to the equations of motion involving spatially varying parameters due to the different material characteristics of the carrier structure and the attached MFC-actuators. The flat output is constructed by exploiting the spectral system representation and enables a differential parameterization of the system states and inputs. This parameterization transfers the motion planning problem into a trajectory assignment problem for the flat output. The resulting flatness-based feedforward control law is analyzed and evaluated at an experimental setup. To increase the performance and the robustness w.r.t. model uncertainties and external disturbances the flatness-based feedforward control is amended by a feedback controller with observer in the spirit of the two-degrees-of-freedom control approach.

Mixed local motion planning and tracking control framework for autonomous vehicles based on model predictive control

This study proposes a novel mixed motion planning and tracking (MPT) control framework for autonomous vehicles (AVs) based on model predictive control (MPC), which is made up of an MPC-based longitudinal motion planning module, a feed-forward longitudinal motion tracking module, and an MPC-based integrated lateral motion planning and tracking module. First, given the global reference path and the surroundings information obtained from onboard devices and V2X network, the longitudinal motion planning based on a vehicle kinematics model is applied to determine the local target path, the desired longitudinal acceleration, and velocity considering the longitudinal safety priority. Then, based on the planned target path and longitudinal velocity, the integrated lateral MPT module based on a 2 degree-of-freedom vehicle model is developed to determine the optimal steering angle while satisfying the multiple kinematics and dynamics constraints. Finally, based on the desired longitudinal acceleration and the steering angle, the longitudinal forces of tires are determined. More importantly, co-simulations under several typical scenarios between MATLAB/Simulink and CarSim are conducted, and the results demonstrate excellent performance of the proposed mixed framework in both planning and tracking and also its real-time implementation.

Dual-quaternion-based modeling and control for motion tracking of a tumbling target

This paper investigates the problem of controlling a chasing spacecraft (chaser) to track and rendezvous with an uncontrolled target. Based on the actual situation, the torque-free motion of an axisymmetric prolate rigid body is employed to represent the short-term attitude motion of the tumbling target. By taking advantage of the dual quaternion's compact and efficient description of the general rigid motion, the coupled and integrated model of the 6-degree-of-freedom (6-DOF) relative motion between the chaser and the tumbling target is derived in the chaser's body fixed frame after taking full consideration of coordinate transformation. Based on the logarithm of dual quaternion, a sliding mode control (SMC) law based on the exponential reaching law and the continuous relay function is brought forward to address the problem of synchronization control of the 6-DOF relative motion. Simulation results illustrate the effectiveness of the proposed method.

Стенд для испытания бесступенчатого дифференциального механизма поворота со следящей системой управления движением гусеничного промышленного трактора

The curvilinear movement of tracked vehicles is controlled by the mismatch of track speeds. Appearance of sufficient installation power at an affordable price on the market of hydrostatic transmissions made it possible to organize stepless control of the turning radius both in the transport mode and when performing technological operations of bulldozing and loosening. External interference distorts the path defined by the joystick. To correct the trajectory, navigation systems are used, which also became available to manufacturers and consumers of industrial tractors. To test control algorithms for a tracked vehicle, bench test equipment is required. The article is devoted to the testing of tracked industrial tractors with modern navigation systems, in particular bench research tests of a stepless differential mechanism for turning machines with a tracking motion control system. The stand, which contains the test drive stepless differential rotation mechanism (BDM) with a motion tracking control system (CCM) motionlessly mounted on the base of a car frame with a drive, and is also equipped with guiding devices to provide a given spatial movement of a single gyrocompass with an accelerometer, entering -which is part of the SSU movement. The technical result is the expansion of the functionality of the stand, which allows to determine the operability and configure the control system by the motion, as well as to control the main parameters of the BDM by simulating in stationary bench conditions the input effects on the elements of the control system, which to the maximum extent correspond to the actual conditions of movement of the machine in the space , while reducing the complexity and cost of these works, by eliminating the need to use vehicles.

Repeated Impact-Based Capture of a Spinning Object by a Dual-Arm Space Robot.

This paper presents detumbling and capture of space debris by a dual-arm space robot for active space debris removal missions. Space debris, such as a malfunctioning satellite or a rocket upper stage, often has uncontrolled tumbling motion. It also has uncertainties in its parameters, such as inertial characteristics or surface frictional roughness. These factors make the debris capture missions difficult to accomplish. To cope with such challenging missions, we propose a detumbling and capture control method for a dual-arm robot based on repeated impact capable of suppressing the debris motion by repeatedly utilizing an effect of a passive damping factor in the contact characteristics. In this paper, as the initial step of a study on the repeated impact-based capture method, we assume that the capture target is a rocket upper stage that can be simply modeled as a cylindrical body and mainly has angular velocity motion in its principle axis of inertia. A motion tracking control law of an end-effector of the robot arm is introduced to maintain the repeated impact. The proposed control method enables the robot to accomplish the detumbling and capture without precise estimation of the inertial characteristics and surface frictional roughness of the debris. The validity of the proposed method is presented by numerical simulations and planar microgravity experiments using an air-floating system. In particular, the experimental evaluation shows the fundamental feasibility of the proposed method, and thus, the result contributes to a practical application.

Integral backstepping control for trajectory and yaw motion tracking of quadrotors

SUMMARYThis work presents a novel trajectory tracking, hovering, and yaw motion control for quadrotors subject to unknown modeling uncertainties and disturbances. Nonlinear equations of motion are used to model the quadrotor's motion without any simplifying assumptions. An integral backstepping control is developed by defining the tracking errors, their integral, and their first through third time derivatives as the system states. The resulting surge force and roll and pitch moments are shown to asymptotically stabilize the error states subject to bounded disturbances and modeling uncertainties. Similarly, a yaw moment is derived through integral backstepping that simultaneously stabilizes yaw motion errors. The controller performance in simultaneous trajectory and yaw motion tracking is verified through both simulations and experiments.

Path Tracking on Autonomous Vehicle for Severe Maneuvre

Autonomous vehicle consists self-learning process consists recognizing environment, real time localization, path planning and motion tracking control. Path tracking is an important aspect on autonomous vehicle. The main purpose path tracking is the autonomous vehicle have an ability to follow the predefined path with zero steady state error. The non-linearity of the vehicle dynamic cause some difficulties in path tracking problems. This paper proposes a path tracking control for autonomous vehicle. The controller consists of a relationship between lateral error, longitudinal velocity, the heading error and the reference yaw rate. In addition, the yaw rate controller developed based on the vehicle and tyre model. The effectiveness of the proposed controller is demonstrated by a simulation.

Nonlinear Adaptive Control of Hydraulic System With Observing and Compensating Mismatching Uncertainties

Hydraulic servomechanism is the typical mechanical/hydraulic double-dynamics coupling system with heavy nonlinearity, parametric uncertainties, and mismatching uncertainties input problems. How to estimate and compensate mismatching uncertainties by observer is a very important issue. This paper proposes an extended-state-observer (ESO)-based nonlinear adaptive control scheme for the motion tracking control of the hydraulic valve-controlled single-rod actuator system. This paper provides a solution to estimate and compensate the mismatching disturbances, i.e., the mechanical dynamics uncertainties. With the developed method, both the hydraulic dynamics uncertainties and the mechanical dynamics uncertainties can be estimated and compensated effectively. Moreover, the parameters adaptive mechanism is also supplemented with ESO to further improve the tracking performance. The parametric uncertainties, modeling, and unknown external disturbances are comprehensively addressed. In theory, the asymptotic tracking can be achieved even in the presence of unknown external constant disturbances and parametric uncertainties. Besides giving the theoretical results and proof, the effectiveness of the proposed method is verified through extensive comparative experiments.

Enhanced Robust Motion Tracking Control for 6 Degree-of-freedom Industrial Assembly Robot with Disturbance Adaption

Industrial assembly robots are designed to enable accurate and repeatable tracking of the positions and orientations of the robot’s end-effector and are hence often required to perform complex tasks within uncertain environments. Therefore, trajectory tracking control is vital to the wide range of applications of industrial robotic systems. This paper presents an enhanced robust motion tracking controller with disturbance adaption for trajectory tracking control of industrial assembly robot. The dynamics of the industrial assembly robotic system is formulated in the working space of the end-effector and the tracking control problem is then formulated. The enhanced robust motion tracking control is synthesized by using disturbance adaption and modified iterative control terms, which is a refined version of conventional robust adaptive control with only disturbance rejection. The capability and effectiveness of the enhanced robust motion tracking control have been evaluated based on an industrial robotic platform. The comparative results clearly show that the proposed control can be used to better minimize the trajectory tracking errors in finite time as compared with conventional proportional derivative control.

Structure singular value theory based robust motion control of live maintenance robot with reconfigurable terminal function for high voltage transmission line

In a complex rigid–flexible coupling environment of overhead high-voltage transmission line, the manipulator robust trajectory tracking motion control of live maintenance robot is the premise of fulfilling the entire maintenance operations. In the process of manipulator’s different function reconfigurable (drainage board bolt tightening and insulator strings replacement), in response to the shortage of excessive pursuit of robust stability for robot manipulator when using H∞ control, as it ignores the influence of structure changes caused by terminal reconfigurable on the system stability to a certain extent, the structured singular value theory–based robot robust μ synthesis control method was proposed in this article. The intrinsic relationship between structured singular value control (μ method) and H∞ control was elaborated, a general control model of the multi-arms and multi-actions robot system was established, the multifunction terminal reconfigurable live maintenance robot with its two kinds of operations was set as a research object, and the corresponding robot μ controller was designed. In the MATLAB development environment, simulation results have shown that on the premise of maintaining the robust stability, compared to the H∞ control method, μ control can obtain better performance robustness for the perturbation of its own structural changes in the process of different operation functions switch. Finally, the validity and engineering practicability of this method is verified by actual 220 kV live operation experiments.

Safety Tracking Motion Control Based on Forbidden Virtual Fixtures in Robot Assisted Nasal Surgery

Traditional nasal surgery requires the doctor’s left hand to carry the endoscope and right hand to complete the surgical operation using unstable images, potentially leading to danger due to mental fatigue, which may greatly prolong the operation time. Previously, robots in robot assisted endoscope sinus surgery (RAESS) only used simple linear motion control, lacked a dynamic tracking mechanism, and had no effective safety protection constraints, such as virtual fixtures or real-time force sensors. This paper describes an innovative and secure robotic control strategy for a dynamic automatic tracking endoscope with doctor input based on the mixed constraint of a dual-layer hyperboloid virtual fixture generated by a series of key points around the nasal cavity and a model of the threshold contact force. A tracking control strategy is set up after calibrating the navigation system and motion filtering via a human-machine interaction. Several experiments show that the hyperboloid virtual fixtures can generate an efficient constraint of different robotic motions and that the robot can automatically execute a track mission with high precision. The proposed safety protection method can be easily applied to patients with different nose shapes and greatly improve the quality of surgery.