Thermal Tactile Perception

Using thermal tactile sensing mechanism based on semi-infinite body model, and combining with the advantages of maximum proportional controller, fuzzy and PID controller, a thermal tactile perception and reproduction experiment device (TTPRED) was designed based on the composite control strategy of threshold switching. The finger difference threshold measurement experiment of thermal tactile was carried out and the finger thermal tactile difference threshold was measured. The relationship between thermal tactile sensation and emotion based on temperature cues has been explored. The experiment results show that, the temperature control range of TTPRED is from -10℃ to 130℃, the temperature resolution and precision are 0.01℃ and ±0.1℃ respectively, the maximum heating or cooling rate is greater than 12℃, and the TTPRED can realize the temperature output of the specific waveform quickly and accurately. The experiment results of psychophysical experiment will provide the experimental foundations and technical support for the further study of thermal tactile perception and reproduction.

Thermal Tactile Perception

Using thermal tactile sensing mechanism based on semi-infinite body model, and combining with the advantages of maximum proportional controller, fuzzy and PID controller, a thermal tactile perception and reproduction experiment device (TTPRED) was designed based on the composite control strategy of threshold switching. The finger difference threshold measurement experiment of thermal tactile was carried out and the finger thermal tactile difference threshold was measured. The relationship between thermal tactile sensation and emotion based on temperature cues has been explored. The experiment results show that, the temperature control range of TTPRED is from -10℃ to 130℃, the temperature resolution and precision are 0.01℃ and ±0.1℃ respectively, the maximum heating or cooling rate is greater than 12℃, and the TTPRED can realize the temperature output of the specific waveform quickly and accurately. The experiment results of psychophysical experiment will provide the experimental foundations and technical support for the further study of thermal tactile perception and reproduction.

Proportional control moment gyroscope for two-wheeled self-balancing robot

A two-wheeled self-balancing robot is considered for investigating the responses of a control moment gyroscope powered by a proportional controller to prevent the robot rollover against the constant inertia forces because of accelerations of the wheels of the robot. The amplitudes of the frequency equations related to the required angular momentum of flywheels with an optimum controller gain were also found. A simulation model of the robot using computer-aided engineering software (RecurDyn) is built to verify the equations of a Lagrangian model. The results of both obtained from the Lagrangian and that from RecurDyn simulations are analyzed comparatively, in which the proportional control loop reduces the required flywheel speeds Ω of gyros and keeps the robot in a very small amplitude of a stable sinusoidal motion in the upright position.

Optimal tuning of a proportional controller for DC motor position control via Fibonacci Search Method

One of the advantages of using DC motors is the ease of controlling their position and speed by manipulating the input voltage. To this, feedback PID-based controllers can be used. However, adjusting these controllers can be challenging and require some reasonable effort from the controller designer. This work proposes an algorithm based on the Fibonacci Search Method to determine the optimal gain of a proportional controller applied to the position control of a DC motor. The project specifications were minimum settling time with null overshoot. The results obtained showed that the proposed method is valid for determining the Kp gain according to the plant and the conditions involved. The proposed method was compared with other optimization techniques such as Golden Section, Quasi-Newton and Grey Wolf Optimization, standing out for its simplicity of implementation, low number of iterations and fast convergence.

Improved Continuous-Cycling Method for PID Autotuning

An improved continuous-cycling method is proposed for the autotuning of the proportional–integral–derivative (PID) controller. The proposed method can identify the frequency response of the process at a preset phase angle without a modeling error. Moreover, it provides an exact frequency response even if a static disturbance is present. The proposed method is an improved version of the continuous-cycling method. The gain of the proportional controller in the continuous-cycling method is updated to obtain the continuous-cycling status automatically. To guarantee the preset phase angle of the frequency response, we place a phase shifter in the form of a time delay after the proportional controller. The results of simulation and experimental studies show that the proposed method can provide an exact frequency response even under static disturbance conditions and can be applied to real processes.

Spatial Path Tracking Controllers for Autonomous Ground Vehicles: Conventional and Nonconventional Schemes

Unlike time-based path tracking controllers, the [Formula: see text]-controller is a spatial path tracking controller. It is a purely geometric path tracking controller and essentially a P-controller to maintain the reasonable spatial distance, [Formula: see text], from the vehicle to the desired path. In this paper, we present some enhancement schemes using the non-conventional PI control laws via optimization. We propose to use a nonlinear term [Formula: see text] for the proportional controller. A fractional-order integral used to achieve a PI[Formula: see text] control. Among the schemes, an optimization search procedure applied to find optimal controller gains by meshing the regions around the values from approximate linear designs. The performance index for parametric optimization is the integration of the absolute purely spatial deviation from the desired path. Three different types of road shape were chosen and the Gazebo-ROS simulation results were presented to show the effectiveness of the proposed enhancement schemes. The results show that in some cases a smaller [Formula: see text] and [Formula: see text] can be achieved by using [Formula: see text] controller, but its disadvantage is there may be some oscillation. For PI[Formula: see text] controller, there is an additional adjustable parameter [Formula: see text], better performance can be achieved without significant disadvantages which is worth in-depth research.

A robust nonlinear control strategy of a PV System connected to the three-phase grid based on backstepping and PSO technique

This article presents a robust non-linear control technique of the three-phase photovoltaic system. The structure chosen for this PV system is that of two power converters and DC voltage intermediate bus. The two power converters are: the DC-DC converter and the three-phase inverter, which requires two main controllers. These controllers have three main objectives. The first objective is to impose the PV voltage generated by the photovoltaic panel, in order to follow a maximum reference voltage provided by the MPPT block. The second one is to maintain the DC link voltage to a constant value, in order to optimize the transfer of energy between the two power converters. The last objective is to inject a three-phase sinusoidal current into the grid, while respecting a unit power factor. With the intention to achieve these three objectives, we designed cascading nonlinear controllers by using the technique of non-linear backstepping control in the synthesis of these two controllers, based on the Lyapunov function, with regard to maximise the PVG output voltage, in order to have a unitary power factor at the grid side. In order to regulate DC-link voltage, we developed an integral proportional controller (PI) with parameters that are optimized by the Particle Swarm Optimization (PSO) method. The robustness of the controller designed approach is tested by a simulation in MATLAB/Simulink software, that improves the performances of each controller whatever conditions of climate.

Using Repetitive Control with Force Feedback to Reduce Impedance of Exoskeletons for Gait Training

Transparent interaction, or the reduction of human-robot interaction forces, is an important quality of gait training exoskeletons. In this paper, we investigate the feasibility of using a repetitive controller for reducing impedance of gait training exoskeletons using force feedback. We used a two-mass spring damper model system, and simulated the application of repetitive force controllers with the objective of reducing the end-point impedance of the distal mass. We designed and applied three repetitive controllers: a 1st order, a 2nd order designed for random signal period error, and a 2nd order designed for constant signal period error. We compared these three repetitive controllers subject to plant model parameter error, random signal period error, and constant signal period error. Numerical simulations under nominal conditions show that via repetitive force control, it is possible to reduce the endpoint impedance to the targeted magnitude and RMSE force below the limit achievable with force controllers while guaranteeing passivity. Furthermore, we established that the application of a 2nd order repetitive controller designed for random period error is highly robust to random period error - exceeding the performance of the passive proportional controller up to 30% error of nominal frequency. Furthermore, this 2nd order repetitive controller designed for random period error maintains a 100% convergence rate through 60% plant parameter error.

An improving control strategy for grid -connected current in weak grid

The traditional proportional feedforward control strategy can suppress the low order harmonics in the strong power grid, but in the weak power grid environment, the grid impedance will have an adverse impact on the stability of the system, resulting in the proportional feedforward control can not suppress the low order harmonics well. In order to solve this problem, a control strategy combining resonant feedforward and new repetitive proportional controller is proposed. Firstly, the stability of traditional proportional feedforward and resonant feedforward systems is analyzed and compared by impedance analysis method. Then, a new repetitive controller is added to suppress low order harmonics based on resonant feedforward control, and the stability of single-phase LCL grid connected inverter system is analyzed Matlab / Simulink is used to simulate and verify the system. The results show that the system stability and the ability to suppress low order harmonics are significantly improved.

GPC and PI Controllers Applied to an Aerothermic Process

The aerothermic process is a laboratory ventilation and heating system. It is assembled with a heating grate and fan systems, completely associated through the data acquisition system (Humusoft MF624) for real-time control. Its air temperature variable constitutes an element that must be operated for energy saving. In order to keep this variable around a desired value, this article presents an experimental comparison between generalized predictive control (GPC) and integral proportional controller (PI). Both techniques are designed using a model obtained from experimental online data. The effectiveness of two methods is demonstrated by an implementation on an aerothermic process. Experimental results show that the main control objectives, such as set-point tracking and the perturbation rejection, are well achieved. The obtained results in closed loop of the PI controller, are promising in comparison to those the GPC ones.