DE OLIVEIRA TAVARES LUIS MIGUEL (PT)
CARDOSO SILVA SEQUEIRA JOAO FE (PT)
DE OLIVEIRA TAVARES LUIS MIGUE (PT)
| CN1658460A | 2005-08-24 |
SERGE MONTAMBAULT ET AL: "LineScout Technology: Development of an Inspection Robot Capable of Clearing Obstacles While Operating on a Live Line" TRANSMISSION & DISTRIBUTION CONSTRUCTION, OPERATION AND LIVE-LINE MAINTENANCE, 2006. ESMO 2006. IEEE 11TH INTERNATIONAL CONFERENCE ON, IEEE, PI, 1 October 2006 (2006-10-01), XP031070253 ISBN: 978-1-4244-0723-1
TANG LI ET AL: "Development of an inspection robot control system for 500kv extra-high voltage power transmission lines" SICE 2004 ANNUAL CONFERENCE, IEEE, PISCATAWAY, NJ, USA, vol. 2, 4 August 2004 (2004-08-04), pages 1825-1830, XP010824751 ISBN: 978-4-907764-22-7 cited in the application
CLAIMS
1. Robot capable of moving on suspended lines/cables and overcoming the obstacles, namely (i) the support systems that hold the lines, and (ii) objects with physical dimensions comparable to those of the robot proposed in this document, and with a kinematic structure including :
a. A main body with 5 degrees-of-freedom, able to ensure the full reachability of the space in the neighborhood of the line close to the robot, allowing a locomotion gait either statically stable or dynamically stable, depending on the specific control system, composed by 2 groups of bodies each with 2 rotation joints (total of 4 jc-ints.) and 1 linear joint located between these groups;
b. Three grasping systems (claws) to allow the connection between the robot and the line, allowing the adjustment of the relative orientation between the robot and the line and different degrees of compliance in the grasping, meaning that each claw can grab the line rigidly or allow some sliding (compliant grasping) ;
c. A reachable space that allows the overcoming of obstacles common in suspended lines and of "the systems that support the lines; d. Individual controllers for each actuator and a global controller to generate the locomotion gait and manage all the functions necessary to the tasks assigned to he robot;
e. A payload area to carry onboard sensors for monitoring task specific variables and/or tools for the execution of repairing tasks on the lines.
2. Robot capable of moving over suspended cables, according to Claim 1/ characterized by having each of the grasping systems with force compliant control that allows the grasping between fully rigid and sliding/ using spherical joints between the main body and the grasping claws .
3. Robot capable of moving oh suspended cables, according Claim 1, characterized by using a statically stable locomotion gait independently of the progression of the line, including changes of direction out of the plane defined by the catenary curve, being possible multiple variants in the locomotion gait, and with the robot moving through the combined action of the joints in the main body and the grasping claws, that yield a cabbage worm like motion.
4. Robot capable of moving on suspended lines according the previous claims, characterized by having the locomotion gait generated by the combined action of the joints in the main body and of the grasping claws, according to 3 base patterns:
a. In lines without obstacles, in which claw 2 can grasp the line in a compliant way (being allowed to slide) or be completely detached from the line and the motion is obtained by the combined action of joints 1, and 5 and claws 1 and 3?
b. In the presence of obstacles, in which claw 2 is used to stabilize the robot, and the progression is obtained accprding to 3 phases/ in the 1st phase the robot moves such that the obstacle gets into the space between claws 2 and 3; in the 2nd phase the robot moves such that the obstacle gets into the space between claws 1 an4 2; in the 3rd phase the obstacle is left behind the robot as the robot moves forward.
5. Robot capable of moving on suspended lines according the previous claims, characterized by performing autonomously generic inspection/monitoring/repairing tasks from its position on the line, namely:
a. Inspection tasks on electric power lines and respective infrastructures?
b. Repairing tasks; the specific class of tasks is limited by the physical dimensions of the robot (which constrain the payload and the amplitude of the motion) and operational conditions, namely atmospheric;
c. Inspection/monitoring tasks of generic activities occurring both on the ground and in the aerial space, such as forest surveillance (wildlife, forest fires) and intruder detection in reserved areas.
6. Robot capable of moving in suspended cables according to the previous claims, characterized by a locomotion gait either controlled by remote teleoperation or in a completely autonomous form, according to instructions (program) contained in an onboard computer equipped with software to manage:
a. Proprioceptive sensots associated to the control of the actuators/
b. Sensors required by the tasks assigned to the robot;
c. Locomotion gait strategies adapted to whatever operational scenarios the robot is in;
d. Communications with remote clients/operators..
7. Robot capable of moving on suspended cables, according to the previous claims, characterized by having an onboard computer with programs for the control and management of the operations with functional description in Diagram of Figure 6.
8. Robot capable of moving on suspended cables, according to the previous claims, characterized by having an onboard computer with programs for the management and control of the locomotion organized according the functional description in Diagram of Figure 7.
9. Robot capable of moving on suspended cables, according to the previous claims, characterized by having an onboard computer with programs for the management and control of the locomotion in the absence of obstacles in the line/cable, organized according the functional description in Diagram of Figure 8.
10» Robot capable of moving on suspended cables, according to the previous claims, characterized by having an onboard computer with programs for the management and control of the locomotion in the presence of obstacles arising in the cable/line, organized according the functional description In Diagram of Figure 9.
11, Robot capable of moving on suspended cables, according to the previous claims, characterized by having an onboard computer with programs for the management and control of the locomotion with the transposition of the supports of the line/cable, organized according to the functional description in Diagram of Figure 9, the region in the neighborhood of the point where the line contacts with the support system is considered as a physical obstacle. |
DESCRIPTION
"ROBOT CAPABLE OF MOVING HANGING IN SUSPENDED LINES"
1. Problem statement
Concerning this robot, the issues of (i) autonomous locomotion of robots over suspended lines/cables, and (ii) control of this type of robots aiming at their use in generic applications, are studied.
Typical examples of applications using this robot are
• The inspection/monitoring of electric power lines and other generic suspended lines,
• The surveillance of wide areas to prevent intrusion, fires, etc, • The monitoring of environmental variables, wildlife, etc,
• Repairing tasks of the lines over which the robot moves itself.
The diagrams presented in the document follow the conventions common in the Robotics area.
2. State of the art
At present time, in the area of inspection/
maintenance/surveillance of the lines used to distribute electric energy there is not a robot with the characteristics described in this document.
From an academic standpoint, dynamically stable brachiate locomotion (inspired in the gaits used by some simian) over lines/cables was studied in [I]. This type of locomotion requires a carefully controlled balance by the robot, using large amplitude movements, and hence it is not well adapted to missions where a payload of heteroceptive sensors, or tools, may require very stable platforms. A typical example is image acquisition devices (e.g., video, laser, etc) that require stable platforms to minimize blurring.
Currently, the inspection of electric power lines is made through the observation either from ground or from helicopters. Whenever needed, experts can make observations and analysis in real time, directly onboard the helicopter, 13] . This mode of operation is expensive and encompasses potential risks for all the workers involved in such missions, As an example, the close inspection using a helicopter requires flying paths at a distance of about 15 meters from the line to get the required level of detail. Besides the economical costs, this tends to induce high levels of physic fatigue in pilots and operators of the sensing systems and hence it is potentially dangerous for the workers involved.
Small size helicopters of multiple types have been used in proposals by several research groups, [4,5] -
Such robots can carry generic payloads, e.g., detectors of anomalies in the electromagnetic fields, infrared and visible imaging devices , communication systems with remote stations, etc. Autonomous helicopter flying is currently an area of intense research but there are not yet systems with decision capabilities similar to those present in traditional, human controlled, devices.
In what concerns the environmental monitoring tasks, the proposals are limited to
• Ground based robots, either wheel based of legged based locomotion (this context is a classical area of research in Robotics, i.e., the land navigation of mobile robots, and there is an extensive bibliography on the subject) , and to the
• Dse of static sensors (vide, for example, the CICLOPE system, developed by INESC-INOV, [9], for forest monitoring) .
In [6 f 7] it is proposed an approach based on a double pendulum robot. Figure 1 shows the corresponding kinematic diagram for such robot. The reachable space includes a wide neighborhood of the lines. Both lines developing along a vertical plane and lines that change direction in the horizontal plane are considered. The 2 degrees-of-freedom at each extremity allow the adjustment of both the inclination and vertical rotation of the body
of the robot. The vertical rotation, performed through joints 1 and 5, allows the robot to move on lines, that change direction in the horizontal plane. This structure allows the overcoming of the obstacles commonly arising in electric power lines, e.g., aircraft and bird markers.
In theory, this robot is able of both statically and dinamically stable motion. The claws at the extremities grab the line, alternating and using a rigid grasp, setting the base point that allows the movement of the main body formed by joint 3 and the rigid bodies linked to it. For an important class of applications of interest, e.g., inspection of electric power lines, dynamically stable locomotion presents the aforementioned problems and also demands minimal physical dimensions for the robots in order that common obstacles can be overcame. For such class of applications statically stable locomotion requires high joint torques, out of the range currently allowed by commercially available actuators.
The robot proposed in [8] (vide the kinematic structure in Figure 2, extracted from [8].) tries to solve the stability issue using a large number of degrees-of- freedom. This robot has similarities with the proposal in this document. However, for the applications of interest
(referred in Section 1), the increase in the weight due to the additional degrees-of-freedom rends . difficult its practical implementation. This issue is also common to other studies in this area in which the practical
feasibility of the robots is obtained only for small physical dimensions and hence restricting the class of applications .
3. Proposed solution
The proposed solution is well adapted to the operation in remote areas or in areas of difficult orography. Some of these applications are specially relevant in social and economical terms. The inspection of electrical power lines in one of such applications.
The robot proposed in this patent application has a kinematic structure composed by a main body and 3 points for grabbing/grasping the line/cable. The main body is composed by 2 groups of bodies having 2 rotation joints each (total of 4 joints), and 1 linear joint in the middle. The points of fixation between the body and the line, hereafter named claws, are also able to adjust its orientation relative to the line and also controlling the compliance of the grasping. Each claw can grab the line rigidly or with some compliance, for instance to allow the sliding of the claw along the line.
Different lpcomotion gaits are possible with this structure. Figure 4 shows (using a simplified diagram) a number of phases for one variant of the locomotion gait in lines without obstacles. Claw 1 grabs the line rigidly whereas claw 3 uses the adequate compliance to grab the
line and allowing some sliding. Claw 2 is completely detached from the line. When the claw 3 has already moved forward enough it grabs the line rigidly, claw 1 starts sliding on the line, and joints 1 and 5 start a contraction process that makes claw 1 move forward. By repeating this motion pattern one obtains a cabbage worm like gait. Joints 2 and 4 are used to allow the changing of direction in the horizontal plane.
In the presence of obstacles claw 2 is used to stabilize the robot. Figure 5 shows the sequence of steps. There is a rigid connection between the robot and the line through claw 1 whereas claw 2 slides along the line as the result of the motion of the joints. This worm like motion {which has of course similarities with that performed in the absence of obstacles) obtained by the coordination of claws 1 and 2, the robot places itself in a position in which the obstacle is contained in the space between claw 2 and claw 3. After claw 3 grabbed the line, claw 2 frees itself from the line and the robot moves forward (again with the cabbage worm like gait obtained by the coordination of claws 1 and 3) until the obstacle lies in the space between claws 1 and 2. At this point claw 2 reconnects to the line and claw 1 detaches completely from the line. The gait obtained by the coordination between claws 2 and 3 makes the robot to move forward in such a way that the obstacle lies completely outside the projection of the robot on the line. As a last step, claw 1 reconnects to the line.
The degrees-of-freedom, of the robot (composed by the rotation and linear joints in the main body e claws) are controlled by individual controllers available off-the- shelf and managed by a central computer onboard the robot. This computer (i) executes specific programs to generate all the phases in the locomotion gait, (ii) manages the mission assigned to the robot, e.g., inspect the line, or survey an area in the ground, or make small repairs on the line, and (iii) maintains the communication with remote operators for data exchange and execution of commands issued remotely.
The onboard computer allows a high degree of flexibility. It is a global objective that the system be completely autonomous during large periods of time, registering relevant data for a posteriori processing.
4, Characteristics of the proposed robot
The proposed robot constitutes a platform capable of locomotion in suspended lines/cables and overcoming of obstacles in these lines, namely (i) the systems that suspend the cables, and (ii) the objects of physical dimensions comparable to those of the proposed robot.
The robot can move itself along any direction the line describes.
The robot has the capability to perform autonomously generic tasks of inspection/monitoring/ repairing from its position on hanging on the line, namely,
a. Inspection tasks on electric power lines and on the associated infrastructures (currently executed by non autonomous systems, with human operators acting locally or remotely under high risk conditions) ;
b. Repairing tasks; the specific class of tasks is limited by the dimensions of the robot (which in turn limits the payload) and conditions in the scenario of operation, namely atmospheric;
c. Inspection/monitoring tasks of generic ground and aerial activities, such as, forest surveillance (wildlife, forestry fires) and intruder detection in reserved areas.
The robot contains a total of 5 joints that allow the complete reachabillity of the space in the neighborhood of the line (vide Figure 3) .
The robot contains a maximum of 3 points for connection to the line, allowing the use of a statically stable locomotion (vide Figure 3) .
Each of the points, of connection to the line (also referred as, claws in this document) has the capability to control
the compliance of the grasping both in position and orientation, ranging between a completely rigid grasp and a level of rigidity that allows the sliding along the line. The functionality that represents the compliant orientation is represented in Figure 3 by the spherical joints place between the main body and the claws. This compliance can be obtained by force control on the claws.
The robot can be controlled by remote teleoperation or in a completely autonomous way, according to instructions (program) contained in an onboard computer.
The robot contains an onboard computer ajid software for the management of a. Proprioceptive sensors, associated to the control of the actuators, b. Sensors necessary to the tasks to be executed, c. The locomotion gait adapted to each operational scenario, d. The communications with remote client systems.
5. Description of the Figures
Figure 1 represents a simple kinematic structure able to move along suspended lines:
♦ (1»1) - Simplified representation of a suspended line/cable *
• (1.2) - Reference frame that defines the plane of the line, i.e., the vertical plane containing a
line/cable suspended between 2 points (in the absence of perturbations) .
• (1.3) - Claw 1.
• (1.4) - Rotation joint 1, with a vertical rotation axis, contained in the vertical plane of the line.
• (1.5) - Rotation joint 2, with rotation axis perpendicular to the plane of the line.
• (1.6) - Rotation joint 3, with rotation axis perpendicular to the plane of the line. • (1.7) - Rotation joint 4, with rotation axis perpendicular to the plane of the line.
• (1.8) - Rotation joint 5, with a vertical rotation axis, contained in the plane of the line.
• U- 9) - Claw 2.
Figure 2 represents the kinematic structure of a robot proposed in [8] . Note that the physical dimensions of this robot make its application in realistic scenarios uncertain.
Figure 3 represents the kinematic structure of the proposed robot:
• (3.1) - Reference frame that defines the plane of the line, i.e, the vertical plane that contains the catenary curve formed by a line/cable suspended between 2 points (in the absence of perturbations) . • (3.2) - Claw 1, including the system for grasping the line with compliance control and the associated degrees-of-freedom.
• (3.3) - Simplified representation of a suspended line/cable.
• (3.4) - Claw 2, including the system for grasping the line with compliance control and the associated degrees-of-freedom.
• (3.5) - Claw 3, including the system for grasping the line with compliance control and the associated degrees-of-freedom.
• (3,6) - Joint 1, of rotation type, located in the main body, with rotation axis perpendicular to the line plane.
• (3.7) - Joint 2, of rotation type, located in the main body, with rotation axis perpendicular to the line plane . • (3.8) - Joint 3, of linear type, located in the main body of the robot, with motion axis in the plane of the line.
• (3.9) - Main body of the robot.
• (3.10) - Joint 4, of rotation type, located in the main body, with vertical rotation axis contained in the plane of the line *
• (3.11) - Joint 5, of rotation type, located in the main body, with rotation axis perpendicular to the line plane.
Figure 4 represents the sequence of stick diagrams of the proposed robot during a forward motion (from left to right) in the absence of obstacles in the line/cable. The numbers 1,2,3, indicate the temporal sequence;
• (4.1) - Simplified representation of a suspended line/cable.
• (4.2) - Rigid grasping point between claw 1 and the suspended line/cable. • (4.3) - Claw 2 free, without any contact with the line.
• (4.4) - Compliant fixation point between the claw 3 and the suspended line/cable.
Figure 5 represents the sequence of ≤tick diagrams of the proposed robot during a forward motion (from left to right) in the presence of obstacles in the line/cable. The diagram illustrates the first phase of the forward motion, where the obstacle gets into the claws 2 and 3. The numbers 1,2 indicate the temporal sequence:
•(5.1) - Simplified representation of a suspended line/cable.
• (5.2) - Rigid grasping point between claw 1 and the suspendend line/cable.
• (5.3) - Compliant grasping point between claw 2 and the suspended line/cable.
• (5.4) - Claw 3 free / without any contact with the line.
Figure 6 represents the flow diagram fox the management programs running on the computer onboard the robot.
Figure 7 represents the flow diagram for the
programs managing (high level control) the locomotion gait and running on the computer onboard the robot.
Figure 8 represents the flow diagram for the programs controlling the locomotion gait in the absence of obstacles in the line/cable.
Figure 9 represents the flow diagram for the programs controlling the locomotion gait in the presence of obstacles in the line/cable.
6. Bibliography
[1] J. Nakanishi, T. Fukuda, D. Koditschek, "A Brachiating Robot Controller", IEEE Transactions on Robotics and Automation, 16(2) :109-123, 2000.
[2] The SkyWrap- http://www.alcoa.com, 2003.
[3] Grid Services GmbH, http://www.grid-services.com.br, 2003.
[4] Autonomous Helicopter Project, Carnegie-Mellon Robotics Institute, http://www-2.cs.cmu.edu, 2003.
[5] The RIPL project, http://www.informatics.bangor.ac.uk/ ~matthew/myprojeσt.php, 2003.
[61 "The Development of a Robotic System for Maintenance
and Inspection of Power Lines", Jose Rocha, Joâo Sequeira, Proceedings of the 35th International Symposium on Robotics, Paris-Nord-Villepinte, France, March 23-26, 2004.
[7] "New Approaches For Surveillance Tasks", Jose Rocha, Joâo Sequeira, Proceedings of the 5 th IFAC International Symposium on Intelligent Autonomous Vehicles, Lisbon, Portugal, July 5-7, 2004.
[8] "Development of An Inspection Robot Control System for 500KV Extra-High Voltage Power Transmission Lines", Tang Li, Fang Lijin, Wang Hongguang, Procs. of the SICE Annual Conference in Sapporo, August 4-6, 2004.
[9] CICLOPE project, http://www.inov.pt/eng/systems/system/ e_ciclopel . html
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