Real-time control of robot manipulators in the presence of obstacles

Kheradpir, S.; Thorp, James S.

doi:10.1109/56.9306

Cited by 12 publications

(5 citation statements)

References 7 publications

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“…Parameters Description a max = 400 cm/s 2 The maximum linear acceleration of the mobile robot ν max = 120 cm/s…”

Section: Motion Analysis On Uneven Terrainmentioning

confidence: 99%

“…A teleoperated mobile robot maneuvered by an operator at a remote site should be able to react autonomously to prevent dangerous situations such as collision with obstacles and turnover. The great deal of study for avoiding obstacle [1][2][3][4][5][6][7] and slip-free control [8][9][10] has been done in the field of the teleoperated mobile robot research. An obstacle avoidance method, a slip-free control method, and a turnover prevention method are essential methods used for controlling a teleoperated mobile robot.…”

Section: Introductionmentioning

confidence: 99%

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Turnover prevention of a mobile robot on uneven terrain using the concept of stability space

2008

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SUMMARYMobile robots in field environment travel not only on even terrain but also on uneven or sloped terrain. Practical methods for preventing turnover of the mobile robot are essential since the turnover of the mobile robot is very perilous. This paper proposes an efficient algorithm for preventing turnover of a mobile robot on uneven terrain by controlling linear acceleration and rotational velocity of the mobile robot. The concept of the modified zero moment point (ZMP) is proposed for evaluating the potential turnover of the mobile robot. Also, the turnover stability indices for linear acceleration and rotational velocity are defined with the modified ZMP. The turnover stability space (TSS) with turnover stability indices is presented to control the mobile robot in order to avoid turnover effectively. Finally, the feasibility and effectiveness of the proposed algorithm are verified through simulations conducted on a three-wheeled mobile robot.

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“…Parameters Description a max = 400 cm/s 2 The maximum linear acceleration of the mobile robot ν max = 120 cm/s…”

Section: Motion Analysis On Uneven Terrainmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Turnover prevention of a mobile robot on uneven terrain using the concept of stability space

2008

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“…where E1 E ( 0 , l ) is a binomially-distributed random variable with parameter q l , i.e., Pr[& = 11 = q2. Then, the first moment of (5) is…”

Section: A Effects Of Stationary Occurrence Of Delays On System Stabmentioning

confidence: 99%

“…In addition to these state constraints, there are usually control input constraints due to the bounds on joint motor torques and energy. In [5], a point robot of Cartesian-coordinate class was modeled by a set of decoupled double integrators:…”

Section: U(k)mentioning

confidence: 99%

“…The robot's end-effector is guided by the control input determined by subject to the control constraints lupl 5 U:", for i = 1 , 2 , and the state constraints specified by the obstacles. The obstacle avoidance strategy (OVS) used in[5] considers the dynamic environment and real-time control needs, where the obstaclerelated state constraints are transformed into state-dependent control constraints by mapping each end-effector's position relative to an obstacle into the P-functionals:P = (zTz)k -(7.2)'"where the obstacle is assumed to be centered at the origin andcovered by a circle of radius T . The k in the P-functional most be chosen such that the set of permissible controls remains nonempty, and the system state and each obstacle's position determine x = [ X I -a , 2 2 -bIT, where ( a ?…”

mentioning

confidence: 99%

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Derivation and application of hard deadlines for real-time control systems

Shin

Kim

1992

IEEE Trans. Syst., Man, Cybern.

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The computation-time delay in the feedback controller of a real-time control system may cause failure to update the control input during one or more sampling periods. If this delay exceeds a certain limit called a hard deadline, either the necessary conditions for system stability are violated or the system leaves the allowed state-space. In such a case a dynamic failure is said to occur to the system. A method for calculating the hard deadlines in linear time-invariant control systems by considering system stability and the allowed state-space is presented. To derive necessary conditions for (asymptotic) system stability, the state difference equation is modified based on an assumed maximum delay and the probability distribution of delays whose magnitudes are less than, or equal to, the assumed maximum delay. Moreover, the allowed state-space-which is derived from given input and state constraints-is used to calculate the hard deadline as a function of time and the system state. A one-shot delay model in which a single event causes a dynamic failure is also considered. The knowledge of hard deadline is then applied to the design of error recovery in a triple modular redundant (TMR) controller computer.0018-9472/92$03.00 0 1992 IEEE

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Joint trajectory generation for redundant robots in an environment with obstacles

Guo

Hsia

1993

J. Robotic Syst.

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Collision avoidance is an absolutely essential requirement for a robot to complete a task in an environment with obstacles. For kinematically redundant robots, collision avoidance can be achieved by making full use of the redundancy. In this article, the problem of determining collision‐free joint space trajectories for redundant robots in an environment with multiple obstacles is considered, and the “command generator” approach is employed to generate such trajectories. In this approach, a nondifferentiable distance objective function is defined and is guaranteed to increase wherever possible along the trajectory through a vector in N(J), the null space of Jacobian matrix J. Algorithms that implement this nondifferentiable optimization problem are fully developed. It is shown that the proposed collision‐free trajectory generation scheme is efficient and practical. Extensive simulation results of a four‐link robot example are presented and analyzed.

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Real-time control of robot manipulators in the presence of obstacles

Cited by 12 publications

References 7 publications

Turnover prevention of a mobile robot on uneven terrain using the concept of stability space

Turnover prevention of a mobile robot on uneven terrain using the concept of stability space

Derivation and application of hard deadlines for real-time control systems

Joint trajectory generation for redundant robots in an environment with obstacles

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