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The perception of touch opens new perspectives for so-called &rsquo, intelligent robotics&rsquo, Force/torque sensors are currently a key component of autonomous assembly processes or of the dynamically developing sector of collaborative robots. Response time is a critical parameter of force control, which has a direct effect on impact forces when the robot initiates contact with the environment. This paper indicates parameters of one of commercial force/torque sensors by JR3, in particular, its pre-defined low-pass filters. Their stationary nature introduces i.e. significant delay in the time domain, resulting in a negative impact on the overall dynamics of force control. To remedy the problem, our proposed approach is to employ a novel discrete time-variant filter with appropriately modulated parameters, owing to which it is possible to suppress the amplitude of the transient response and, at the same time, to increase the pulsation of damped oscillations, this results in the improvement of the dynamic properties in terms of reducing the duration of transients. Differences between a commercial, stationary filter and the recommended discrete time-variant filter have been shown experimentally, using a dedicated test environment.

This paper presents a concept of time-varying IIR multi-band-stop filter with equalized group delay characteristic in the steady state. The ECG signal is used to test the proposed structure. As the group delay equalizer we used the constrained Newton-type algorithm provided by Matlab. To confirm the robustness of the proposed solutions we also present the experimental results with the aid of noise frequency estimator.

This paper presents a concept of implementing time-varying FIR narrow multi-band-stop filter for fast EMG measurements. The proposed system consists of a notch type filter with predefined time-varying coefficients and an IMU-based trigger to start the measurement of the muscle movement. The coefficients of the proposed filter are calculated according to the defined function in the selected time span. The use of an external trigger, which signals the moment of the muscle movement, allows to use the time-varying filter not only in the beginning of the measurement but also further during the test. The paper is an extension of the previous research in the field of time-varying filtering structures.

In some measurement applications, it is required to have digital filters which simultaneously possess a constant group delay in the passband and a narrow transition band. This kind of filters is usually implemented using allpass filter section which compensates the unfavorable run of the group delay response of the original filter. Unfortunately, the process of equalisation affects the time domain characteristics of the (whole) equalised system. This paper presents theoretical concept and simulation results of a new class of low-pass time-varying infinite impulse response (IIR) filters with equalised group delay response and a transient response of short duration. The improvement of the filters in the time domain is achieved by means of temporary change in the value of the filter parameters. Computer simulations verifying the effectiveness of the proposed IIR filters with equalised group delay response and reduced transient response are presented and compared to the performance of traditional filters.

This paper presents experimental results of a stable time-varying IIR narrow multi-band-stop filter. The design and stability check procedures have been shown. The experimental hardware used to conduct the measurement of the ECG was presented. The concept of the time-varying coefficients was used in order to reduce the transient time of the filtering structure. The advantages of the proposed methodology were confirmed with three test cases focused on denoising the input signal.

The paper presents a concept of designing a stable time-varying IIR narrow multi-band-stop filter. The proposed structure is based on an all-pass prototype. The stability analysis of the time-varying design is presented. In order to reduce the transient time, the varying rejection bandwidth in time is introduced. The paper also presents the idea of the LUT's (Lookup Table) to control the memory usage of the time-varying filtering structure. The results of the methodology are presented and compared with the stationary counterpart. The proposed stable time-varying filtering structure is applied to the noised test signal in the simulation environment.

This paper presents a concept for digital infinite impulse response (IIR) lowpass filter with reduced transient response. The proposed digital filtering structure is based on an analog oscillatory system. In order to design the considered digital filter, the analog prototype is subjected to a discretization process and, then, the parameters describing the dynamical properties of the oscillatory system are temporarily varied in time, so as to suppress the transient response of the designed filter. An optimization method, aimed at reducing the settling time by proper parameter manipulation, is presented. Simulation results, along with a real-life application proving the usefulness of the proposed concept, are also shown and discussed.

The paper presents the equalization problem of non-linear phase response of digital IIR type filters. An improved analytical method of designing a low-order equalizer is presented. The proposed approach is compared with the original method. The genetic algorithm is presented as an iterative method of optimization. The vector and matrix representation of the all-pass equalizer are shown and introduced to the algorithm. The results are compared with the analytical method. In this paper we have also proposed the use of an aging factor and setting the initial population of the genetic algorithm around the solution provided by the analytical methodology

The paper presents a stability analysis of linear time-varying IIR filter with equalized group delay characteristic. A problem of a non-linear phase response of an IIR filter is introduced. An allpass equalizer as a solution is proposed. The changes in the time domain that additional component introduces into the system is pointed out. The linear time-varying difference equation describing the IIR filter is shown. The methodology known from the literature of analysing the stability is presented. Then the algorithm is applied to check the stability of time-varying IIR filter with coefficients improving its time domain characteristic.

Known problem regarding non-linear phase response of IIR filters is pointed out. An analytical approach of compensating group delay response of digital low-pass filters is introduced. The design procedure of an IIR low order equalizer for the elliptic filter is shown. Results are presented and compared with known methods. Proposed methodology is found to be very competitive in terms of preventing amplitude losses.