Impedance control approach in robot's leg dragging velocity variations

One of the challenging areas in developing bio-inspired legged robot is dynamic control, especially in environment interaction. Impedance control is widely used by researchers for dynamic interaction, but the majority only focus on adapting uneven terrain structure. This idea may not be suitable for pick-and-place task robot that has different weight due to its body weight and payload as well as locomotion on flat terrain. Thus, this paper presents leg velocity control through impedance control approach with the aim to increase the energy of the legged robot especially during leg dragging based on force on contact. The results show that proposed controller is applicable since it increases the energy and velocity of leg motion due to increase in force on contact while maintaining the shape of the leg motion

Steering Vehicle with Force-based Impedance Control for Inertia Reduction

This paper presents the inertia control on a steering rack vehicle using interaction control approach through forcebased impedance control. Overdriven factor in a vehicle motion especially on a cornering track, is one of the issues that need to be tackled for safety and energy efficiency. Hence, in the attempt to cope with the issue, this study proposes to implement a dynamic control technique that considers the interaction between the vehicle and its terrain by using indirectly shaping inertia forces. The proposed force-based impedance control is derived by considering the forces developed by the rack steering vehicle and shaping the vehicle velocities as its kinodynamic inputs. The implementation of the proposed dynamic control, emphasis is given to the vertical and horizontal axes of the vehicle body, during which inertia could happen as its velocity is at its lowest. This proposed dynamic control strategy is verified by simulating on the steering system model with road terrain and aerodynamic frictions as disturbances. The simulation results shows that the proposed system is able to reduce the inertia forces via shaping the velocity inputs to the vehicle, even though road terrain and aerodynamic frictions are present in the cornering tracks

Improving pressure valve precision using finite-time prescribed performance with fractional-order proportional, integral and derivative control

The paper presents the improvement of precision control on pneumatic system pressure using Finite-time Prescribed Performance Control with the Fractional-Order Proportional, Integral, and Derivative (FOPID-FTPPC) control. The control strategy is proposed to overcome the nonlinearity produced by the pneumatic system in regulating the pressure on positioning operation. The study was conducted through several experiments with a 5/3-way pneumatic proportional valve that configured with pressure transducers as feedback responses. The study was done with two different types of common input trajectories: step and sinusoidal inputs. The proposed FOPIDFTPPC controller outperforms the FOPID controller by 26% in terms of minimizing the overshoot of the step input trajectory. On the other hand, the proposed controller exhibits significant performance with a sine wave input trajectory, and the advantage of its integration with FTCPPC frameworks allows it to achieve steady state performance even more quickly. The findings demonstrate that the proposed the proposed FOPID-FTPPC controller can regulate the pneumatic systems pressures while eliminating steady-state errors, fast response as well as reducing the overshoot

Forkloader Position Control for A Mini Heavy Loaded Vehicle using Fuzzy Logic-Antiwindup Control

This paper presents a proposed integrated Takagi-Sugeno-Kang (TSK) type Fuzzy Logic control (TSK-FLC) with Antiwindup elements for a forkloader position control of a Mini Heavy Loaded Forklift Autonomous Guided Vehicle (MHeLFAGV). The study was carried out by modeling TSK-FLC as a close-loop control for the each axis of the fork-lift’s movement. The degree of membership is designed with reference to the system response, in which ultrasonic sensor with 1cm resolution is used. Moreover, the rule base is determined and optimized to deal with microcontroller processing speed. In order to cater for the windup phenomenon, a proportional and integrated antiwindup elements are integrated into the TSK-FLC model. This control strategy consumes less memory and is expected to increase the time response of the control system. The experiment and analysis is done on the actual forkloader unit of MHeLFAGV system. The experiment was done on the vertical axis motion since horizontal motion will have the same characteristic pattern of implementation and characteristic of tuning. The experiment shows that the proposed integrated TSK-FLC with antiwindup elements is able to speed up the time response of the system and eliminate the overshoot as well as oscillation on the forkloader movement

Interaction Motion Control on Tri-finger Pneumatic Grasper using Variable Convergence Rate Prescribed Performance Impedance Control with Pressure-based Force Estimator

Pneumatic robot is a fluid dynamic based robot system which possesses immense uncertainties and nonlinearities over its electrical driven counterpart. Requirement for dynamic motion handling further challenged the implemented control system on both aspects of interaction and compliance control. This study especially set to counter the unstable and inadaptable proportional motions of pneumatic robot grasper towards its environment through the employment of Variable Convergence Rate Prescribed Performance Impedance Control (VPPIC) with pressure-based force estimation (PFE). Impedance control was derived for a single finger of Tri-finger Pneumatic Grasper (TPG) robot, with improvement being subsequently made to the controller’s output by appropriation of formulated finite-time prescribed performance control. Produced responses from exerted pressure of the maneuvered pneumatic piston were then recorded via derived PEE with adherence to both dynamics and geometry of the designated finger. Validation of the proposed method was proceeded on both circumstances of human hand as a blockage and ping-pong ball as methodical representation of a fragile object. Developed findings confirmed relatively uniform force sensing ability for both proposed PEE and load sensor as equipped to the robot’s fingertip with respect to the experimented thrusting and holding of a human hand. Sensing capacity of the estimator has also advanced beyond the fingertip to enclose its finger in entirety. Whereas stable interaction control at negligible oscillation has been exhibited from VPPIC against the standard impedance control towards gentle and compression-free handling of fragile objects. Overall positional tracking of the finger, thus, justified VPPIC as a robust mechanism for smooth operation amid and succeed direct object interaction, notwithstanding its transcendence beyond boundaries of the prescribed performance constraint

Pressure Regulation on A Single Finger of Tri-Finger Pneumatic Grasper Robot using Finite Time and Convergence Prescribed Performance Control

This study presents a method for improving the precision of pneumatic pressure regulation and control in a finger of a tri-finger pneumatic grasper (TPG) robot. The method employs finite time and convergence prescribed performance control (FTC-PPC) in conjunction with proportional, integral, and derivative (PID) control as a strategy to overcome the nonlinearity and uncertainties of pressure regulation of the pneumatic system in the TPG. Besides finite-time tuning, the proposed PPC formulation also introduced convergence rate and domain. To test the method, several experiments were conducted using a 5/3-way pneumatic proportional valve (PPV) configuration with pressure transducers for feedback responses. Two different pressure input patterns, a step, and periodic in-put patterns were used in the experiments. The results show that the proposed controller outperformed the PID as well as the finite-time PPC with PID from the previous works in regulating the pressure for a finger of the TPG by average. 10% in terms of minimizing overshoot, suppressing oscillations, and providing a fast response

Optimal finite- time prescribed performance of servo pneumatic positioning with PID control tuning using an evolutionary mating algorithm

This paper presents an optimum tuning on finite-time prescribed performance with PID (FT-PPC-PID) controller using the Evolutionary Mating Algorithm (EMA) approach for a pneumatic servo system’s (PSS) rod-piston positioning. The design objective is to optimize the convergence rate and finite time of the prescribed performance function in error transformation in parallel with PID controller’s gains. The multi-step input trajectory on the PPVDC model plant was used for simulations with specific load and random noise as disturbances. The results demonstrate that the controller optimized with EMA outperforms the same controller optimized with other methods in achieving dynamic multi-step positioning of the rod-piston. This highlights the significant enhancement in overall performance of PPVDC positioning, including the stability of its internal system, through the EMA-optimized finite-time prescribed performance controller with PID

Impedance control approach on leg motion speed variation on soft surface interaction

This article presents the leg speed variation control using impedance control approach on soft surface displacement motion. One of the challenging fields of designing a legged robot that can be equipped with adaptation ability is it dynamic control which majorly involved in interaction with the environment. Numerous researchers have been widely implemented impedance control as dynamic interaction but less emphasized in adapting soft terrain. Most of the impedance control implementation on the legged robot on rough terrain emphasized on position changes, and it may not practical for legged robot navigate on the soft terrain. Soft terrain contains different ground stiffness and medium viscosities. Thus, this study has taken the initiative to propose a speed variation control on a robot’s leg by using a force-based impedance control approach to increase the leg energy exchanges specifically on foot placement. The proposed control was validated in actual robot’s leg, and performances show that the energy in the leg increases as the velocity of leg motion increase due to increase in force feedback while maintaining the shape of the leg motion

Development of wireless passive water quality catchment monitoring system

To maintain the quality of aquatic ecosystems, good water quality is needed. The quality of water needs to be tracked in real-time for environmental protection and tracking pollution sources. This paper aims to describe the development and data acquired for water catchment quality monitoring by using a passive system which includes location tagging. Wireless Passive Water Quality Catchment Monitoring (WPWQCM) System is used to check and monitor water quality continuously. The condition of water in terms of acidity, temperature and light intensity needs to be monitored. WPWQCM System featured four sensors which are a temperature sensor, light intensity sensor, pH sensor and GPS tracker that will float in water to collect the data. GPS tracker on passive water catchment monitoring system is a new feature in the system where the location of water can be identified. With the extra feature, water quality can be mapped and in the future, the source of disturbance can be determined. UMP Lake was chosen to check and monitor the water quality. The system used wireless communication by using XBee Pro as a medium of communication between CT-Uno board and PC

Adjustable convergence rate prescribed performance with fractional-order PID controller for servo pneumatic actuated robot positioning

This study presents the method for optimal error tracking in position control for a servo pneumatic actuated robot grasper system using a new adjustable convergence rate prescribed performance control (ACR-PPC). It focuses on improving the feedback controller and the fractional-order proportional-integral-derivative (FOPID) controller used for the position control of each robot's finger. Multiple features were considered such as tracking error, rising time, faster transient response with finite-time convergence, oscillation reduction, and pressure stabilization in the pneumatic system. Experiments were conducted using a single finger of a tri-finger pneumatic gripper (TPG) robot, actuated by a single proportional valve with a double-acting cylinder (PPVDC). Two types of input trajectories were tested: step and sine wave inputs, which are common and critical for pneumatic systems. The results show that the proposed method eliminates oscillation and achieves high tracking performance within the prescribed bounds and minimal overshoot as well. The oscillation was suppressed with minimal overshoot and fast response was achieved by tuning the formulated adjustable prescribe performance function, thus improving the rising time response without significant loss of performance