Human & Robot Interaction Lab. (TaarLab)

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Control of a Pneumatically Actuated 6-DOF Gough-stewart Platform

People Involved
   Jalal Haji Pour Machiani, Mojtaba Yazdani, Foad Sanie


 

In the most of the works for implementation and control of parallel robots, especially Gough-Stewart platform, electrical servo motors one used and less attention has been paid to pneumatic actuators. The platform understudy has six links for which each link contains one linear potentiometer, for the exact position of link, two pressure indicators, for input and output pressures of the jack, and one valve to adjust the air flow.  In this project, by combining a linear potentiometer, two pressure indicator and a proportional valve in each limb, servo valve has been eliminated.

Then upon apply different levels of input voltage on the actuator, different step responses are studied in the presence of dead zone, delay and saturation. Through a linear identification process, a nominal second-order linear model is estimated for the actuator. Based on the identified model, the position (length) of the actuator is controlled by applying some straightforward and reliable control solutions.

Stewart 

System Identification & Position Control of 3DOF Decouple Parallel Robot

People Involved
   Mohsen Heydarzadeh, Mohammad Sharifzadeh, Jalal Haji Pour Machiani

Kinematic identification of Tripteron robot is one of the purposes of this thesis. Then precise position control could be achieved using identified kinematic parameters of Tripteron robot. For determining the position of end-effector, a special 3-D camera (named Kinect) will be used and image processing algorithms will be applied. In addition, the camera will be used for position control and obstacle avoidance. Finally, the robot should be able to accurately pursue any desired trajectory.

The last step of this thesis is involved with design and development of a user-friend GUI (Graphical User Interface) so that user can simply interact with robot.

tripteron2 

System Identification of NAO

People Involved
   Payam Ghassemi


 

Nao humanoid robot v4 is currently under study in order to explore various topics. NAO is a position-based control humanoid which is one of the main difficulties. System identification is a key point to overcome to these difficulties, and make useful some torque-based control laws. Currently, system identification based on frequency analysis and model based methods are studying which will introduce a transformation for torque to position commands.

Moreover, identification of robot parameters such as masses and inertia tensors, and the motor parameters of each joint.

nao5  c i diag1

Dynamical Control & Identification of 3-DOF Decouple Parallel Mechanism (Tripteron) by Constructing a Human-Robot Interaction Interface

People Involved
   Mohammad Sharifzadeh, Mohsen Heydarzadeh, Jalal Haji Pour Machiani


 

In Dynamical Control & Identification of Tripteron, as a decoupled parallel robot performing 3 translational motion, the main goal is to control the robot by using the torque mode control of the actuators. As a joint work, the dynamic model of the robot will be obtained by MohammadAli Bagherian. In order to reach more accurate control performance, the team will perform system identification techniques on the dynamic model of the robot. This procedure will involve both White-Box Identification (based on provided model from theoretical concepts) and Black-Box Identification (Data Based). The main purpose to perform the identification is to reach the most accurate possible model of system on the presence of uncertainties which are neglected in theoretical dynamics model such as friction and backlash in the joints of the robot. The dynamical control of system would be performed from simple and classical PID controller to more complex ones to reach a stable and efficiency control of the system.

tripteron2 

Stewart Robot

People Involved
   Amir Salimi, Jalal Haji Pour Machiani


 

This project is concentrated on identification-based control methods of pneumatic 6-DOF Gough-Stewart platform. Gough-Stewart platform is a type of parallel robot, having a stationary base platform upon which a moving platform is supported by six links.

For the first step, the control of the Gough-Stewart platform is based on data provided by the pressure sensors. Also local and cascade control loops are suggested. Then a rotation sensor is installed on the end-effector in order to have close-loop control on the end-effector orientation.

Moreover, the IKP (Inverse Kinematic Problem) and FKP (Forward Kinematic Problem) is used by applying an inner and outer control loop. The main objective in this project consists in using all sensors, such as pressure sensor, proportional, orientation sensors by applying data fusion concepts in order to improve the performance of the robot. In addition, for the sake of a better control, vision techniques are applied to calibrate the robot, and a user friendly Graphical User Interface (GUI) is designed.
It should be noted that due to the non-linearity behavior of the mechanisms different control techniques such as sliding mode, adaptive, evolving and STR (Self Tuning Regulator) control methods combined by identification techniques are used. 

Stewart 

Forward and Inverse Dynamic Analysis of Parallel Robots for System Identification

People Involved
   MohammadAli Bagherian, Jalal Haji Pour Machiani


The first step of my master thesis is involved with forward and inverse dynamic models of parallel robots such as Tripteron, Stewart and delta robot. These models, present some relations between the motion of end-effector and forces/torques of active joints. Real-time solution of the problem at hand is one of the goals of this step.

Dynamic identification of parallel robots using these dynamic models is the next step of this work. In this step, system identification methods will apply to reduce the uncertainties and to achieve a precise dynamic model. Finally, a new type of delta-like robot (named X4) will be designed and constructed to be used in experiments associated with this procedure. 

delta1 

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