![]() ![]() Hence, disturbance observers were introduced. Conversely, these force sensors impose measurement limitations due to their high cost, restricted area of contact and noise/ disturbances in the environment. To enable this, force sensors are installed at the end effector providing force feedback control. Whereas transparency is related to the human operator’s potential to sense the slave side interaction with the environment. Stability can be achieved using Proportional integral derivative (PID) controls, wave-variables based passivity control and time-domain passivity approach. One of the main concerns relating to control systems design, is to achieve a decent tradeoff between these two contrasting goals. In teleoperation systems, stability and transparency are both critical properties and conflicting to each other. ![]() Thus, the human operator feels they are directly executing control operation of the remote side themselves.įigure 1: Control system viewpoint of haptic teleoperation system The measured signals (force, position, and vibration) are then fed back to the haptic interface (highlighted in the bottom red circle) resulting in haptic feedback and HITL system. The robot will then exert the received control signal to the concerned object present in the remote environment. Accordingly, the human arm will send force and position signals to the controller (highlighted in the top red circle) which will forward the modified force and position signals to the robot system. Thus, the movement of the human arm is based on the haptic feedback signals received from the haptic interface device. In this haptic teleoperation system, a human operator gets the feel of telepresence in the form of force operation and vibrations (sensations) from the haptic interface system, for instance, a simlulator. The main purpose of this system is the operator’s ability to interact with the remote environment via haptic feedback. The block diagram shown in Figure 1 gives a control system viewpoint of haptic teleoperation system. These operations are performed globally, mainly to aid and assist the population with special needs. Potential applications of teleoperation systems include highly specialized professions like telesurgery, mining, micro, and nanoparticles handling and artificial intelligence to name just a few. Thus, the human operator can execute tasks remotely without physically being present there. In simple text, the human perceives direct control and manipulation of the environment with their own hands, which is achieved by having their actions mediated physically by means of a robot, communication channel and control systems (i.e., controller), by providing the haptic sensing feedback signals (mostly interaction forces and position constraints) to the operators. A typical bilateral teleoperation system consisting of the master device (human operator), communication channel and slave teleoperator, provide human operator’s necessary interface and the experience of ‘telepresence’. Haptic feedback control systems containing human- in- the- loop (HITL) is relatively a young field of research, that display the interaction between human-machine systems. This paper is an extension of work originally presented in 2020 International SAUPEC/RobMech/PRASA Conference. The results of the proposed controller are compared with the Proportional Integral (PI) controller, which suggests that the ADRC controller performs better as compared to the conventional PI controller. Designing of ADRC controller and the human-machine interface (HMI) is followed by their integration, in order to obtain simulation results, thus proving the practicality and validity of the overall system. Modelling of the two- dimensional physical platform is also explained in this article. ![]() This overall physical system constitutes the haptic interface. The concerned electro-mechanical platform consists of dual ball screw driving system and DC motors. The design and simulation for ADRC are established in MATLAB/ Simulink. The ADRC is an unconventional model-independent approach, acknowledged as an effective controller in the existence of total plant uncertainties, and these uncertainties are inclusive of the total disturbances and unknown dynamics of the plant. The motivation for the following scheme originates from the shortcomings faced by classical proportional integral derivative (PID) controllers in control theory. This paper proposes an active disturbance rejection control (ADRC) design for a haptic display platform structure. ![]()
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