Automated Engine Piston Installation Using Industrial Robots

To achieve force control of an industrial robot, this paper proposes an I-PD force control system based on an instantaneous state observer. The structure of the proposed system is based on a resonance ratio control system and a feedback signal of the reaction force response. In this paper, the gain of a pseudo derivation is designed as the feedback gain. From the results of the designed gains, the feedback gain Kf is a negative value. Hence, the resonance ratio control system becomes equivalent to a state feedback. For the stability of the proposed I-PD force control system based on the acceleration control system and a state feedback, a new analysis method is required. This paper analyzes an open-loop of the proposed system considering the bandwidth of the observer. The results of an analysis show that an observer with a wide bandwidth is required. Therefore, the parameters of proposed system using the instantaneous state observer are designed based on the coefficient diagram method. The effectiveness of the proposed method is confirmed by performing numerical simulations based on the model of an industrial robot arm. The results show that the proposed method is effective for the stable force control of an industrial robot arm.

Mitigating collision is a fundamental issue in contact problems, and is required to ensure the safety of a robotic cell. Research into the contact problem between robots and their environment is divided into two parts: one uses the environmental contact model and parameter estimation, the other uses the robot force control method. There are two main problems with this research method. One is that the two research levels are not effectively combined to form a complete solution for force control in practice. The other problem is that research on excessive contact force in the collision phase has not been studied in depth for force control. In this paper, a sensing-executing bionic system is proposed that combines environmental detection and robotic force control based on the way an ant functions. The bionic system clearly explains the process from environment detection to robot control, which can provide guidance when designing a new robot control system. An adaptive switching control algorithm is proposed to mitigate the collision force in the collision phase. From the simulation results, the collision force is significantly reduced due to the implementation of adaptive switching control. Finally, a new self-sensing device is designed which can be integrated into the robot control device. However, as there are no additional sensors or computational complexity in the system, the effectiveness of the circuit and superiority of the adaptive parameter update must be verified by experimentation.

This work addresses the end-effector trajectory-tracking force and motion control of a three-dimensional three-link robot considering measurement noises. The last two links of the manipulator are considered as structurally flexible. An absolute coordinate approach is used while obtaining the dynamic equations to avoid complex dynamic equations. In this approach, each link is modeled as if there is no connection between the links. Then, joint connections are expressed as constraint equations. After that, these constraint equations are used in dynamic equations to decrease the number of equations. Then, the resulting dynamic equations are transformed into a form which is suitable for controller design. Furthermore, the dynamic equations are divided as pseudostatic equilibrium and deviation equations. The control torques resulting from the pseudostatic equilibrium and the elastic deflections are obtained easily as the solution of algebraic equations. On the other hand, the control torques corresponding to the deviations are obtained without any linearization. Encoders, strain gauges, position sensors and force and moment sensors are required for measurements. Low pass filters are considered for the sensors. For the crossover frequencies of the sensors, low and high values are chosen to observe the filtering effect on the robot output.

The empirically developed force control in cases of the robotic polishing and the rehabilitation robots serve as a motivation for the study of the peculiar dynamic behaviour of digital force control. The effect of the sampling times of the digital controllers are studied analytically, and the corresponding stability charts are presented for different gain and mechanical parameters describing also the different sampling frequencies at the force sensors and in the digital control loop. The types of bifurcations are also identified at the stability limits. As one of the practical conclusions, the negative role of differential gain is explained in digital force control.Key wordsforce controlled robotsdifferential gaindelayed oscillator

Robotic force control is a core research direction in robotics technology. For tasks such as polishing and assembly, it requires not only precise motion control but also compliant force control by adjusting output force and torque. Traditional impedance control can ensure accuracy in a single environment, but it is limited by the difficulty in accurately acquiring parameters in complex environments; although variable impedance control can adapt to the environment, it faces challenges in control law design. This paper integrates the extended Twin Delayed Deep Deterministic Policy Gradient (ex-TD3) algorithm with impedance control, proposing an ex-TD3-based intelligent impedance control optimization algorithm. A Python-MATLAB/SimMechanics co-simulation platform is established to verify its effectiveness. The experiment adopts a scenario where the robot moves linearly along the z-axis, with fixed environmental stiffness and the desired tracking force changing in stages over time. The model training is iterated for 300 episodes, after which the reward tends to stabilize and the control strategy converges. Experimental results show that, compared with the traditional adaptive impedance control algorithm, the proposed algorithm in this paper exhibits faster force response, smaller force fluctuations during force step changes, smoother force output throughout the process: the maximum overshoot of force control decreases from 6.21N to 1.33N (a reduction rate of 77.63%), and the maximum position tracking error is reduced by 69.5%. With the above optimized design, this study significantly improves the energy efficiency and long-term operational sustainability of mechatronic systems; its precise control of force overshoot and position tracking error effectively reduces mechanical losses and unnecessary energy consumption during the system’s dynamic interaction with the environment.

A type of open-loop force control scheme has been tested in a sheep-shearing robot. Stable, high speed surface following has been achieved on hard and soft surfaces without having to measure actual contact forces and without knowing the dynamics of the robot or the surface. A small hydraulic actuator holds the cutter against the surface of the sheep with a programmed force obtained by regulating the hydraulic pressure against a piston. Measurement of the cutter position relative to the robot provides guidance to modify the robot's position trajectory, and to compensate the hydraulic pressure for disturbance effects. Experience with this device has suggested a simpler approach to force control which might be helpful for future robot system designers.

Soft robots are increasingly being explored and developed in various settings that demand safe and adaptable interactions between robots and their environments. In addition, soft robots exhibit passive compliant behavior and generate continuous deformations when engaging with the environment. This imposes challenges on achieving active, on-demand interaction force control, especially when feedback force-sensing devices are not available. Consequently, there is a need to explore new model-based force control paradigms for soft robots. In this article, we propose a (quasi-)static force control approach for soft robots based on compliance modeling, avoiding the necessity for feedback control loops or extensive training data collection. The proposed approach can deliver contact force control along three Cartesian axes when the robot is actuated into various configurations. The compliance matrix is derived from the robot configuration, which allows the calculation of desired deflection displacements needed to generate on-demand forces. The resulting force control is achieved by solving inverse kinematics problems based on these deflection displacements. The efficacy of our proposed controller is validated through experiments with both one- and two-segment pneumatic-driven soft continuum robots. The results demonstrate effective static force control performance, with mean control errors below 5% of the desired peak forces.

Force control of industrial robots: The contact problem

Robot force control: A review

Force control is nowadays a mature technology and it is becoming more and more common in robotic applications. A specific and significant example are robotic devices for rehabilitation. Despite this, an effective standardized and comprehensive method to assess force control performance does not exist. Defining the performance of a force-controlled system is not a trivial task, and one of the reasons is that performance does not only depend on the dynamics of the robot, but also on the dynamics of the environment, which are usually uncertain and time-varying. Exerting a force on a soft environment is different from exerting a force on a rigid environment. Indeed, the same force-controlled robot can have different force responses in different environments. This paper proposes a methodology to standardize the benchmarking of force control algorithms applied to different actuation architectures and considering a wide set of possible environments and disturbances, defined by the application of interest.

Most industrial robots are designed to operate as position servo-controlled manipulators, which is appropriate if the robot is to simply follow a predefined trajectory in free space. However, if the robot’s end-effector comes into contact with the environment, then position control generally will not suffice. Stability becomes a major issue when the robot end-effector becomes highly constrained, and the success of the operation is largely dependent upon the correct selection of the gains in the force control algorithm. These gains are themselves dependent upon the compliance at the task interface, and another major difficulty occurs when this is unknown or varying. This paper describes the application of fuzzy logic in the development of an industrial robot force controller, primarily used for robotic deburring operations. Experimental results illustrate the effectiveness of the controller’s self-adjusting gain strategy, and the ability of the robot to successfully carry out a deburring operation.

In general, the contact force, which is used in controller design for robotic compliant motion, can be either explicitly calculated through complicated computation or measured by expensive force sensors. A force control strategy using the estimated contact force is proposed. The estimation of the contact force and states is primarily based on their previous observer design. It is shown that the controller achieves asymptotic stability.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Current manual auditing system may be difficult to the auditors, due to the enormous amount of data. Some auditors probably overlooked some illegal business processes that can cause money loss or embezzlement by the workers. Research study conducted to identify the problem by using the current manual financial auditing system found that the current system is not efficient in continuous auditing for business process. It is known that vast amount of financial data being processed during auditing may slow down the process during auditing. It can also be complex to handle which sometimes can be beyond auditors’ capability to audit business processes. Our research proposes an informative dashboard to assist auditors to assess risk. The informative dashboard is a category of operational dashboard. We apply big data management concept and implement the dashboard using the web development life cycle approach. The dashboard is implemented using R language and Shiny package.

Industrial robots are confronted with performing tasks where a contact with their environment occurs. Therefore, a need for control algorithms with position tracking performance and force control ability appears. Many algorithms have been proposed which deal with robot motion and force control. They could be mainly separated into two classes, namely: hybrid control, where constrained and unconstrained DOFs of the robot are observed separately based on the principle of the orthogonality; and impedance control where the robot should adopt some physical properties such as mass, damping and stiffness in order to assure stable dynamic interaction with the environment. In this paper the robust impedance control law based on the attractive theory of sliding mode is proposed. The control law guarantees a robot predefined impedance and therefore force regulation based on impedance properties is discussed. Experimental results on a simple 1 DOF mechanism is shown to verify theoretical statements.

A dynamic force controller based on momentum is implemented to the redundant system in this paper. With this method, the centrifugal and Coriolis terms are eliminated from the system and precise and stable force control is realized. Firstly, force control based on momentum is described. This controller does not have any singular points and is able to be applied to dynamic state. A null space controller for the dynamic controller is proposed and is constructed in the angular momentum dimension. Then, position and force vector is united into work space using equivalent mass matrix. Several simulation results are shown to confirm the validity of the proposed method.