Background technology
Mobile manipulator is to be fixed on the mobile platform by manipulator to constitute.Manipulator is used for realizing some actions as extracting, operation etc., enlarges the working space of manipulator by moving of platform, and manipulator can be executed the task with attitude more suitably.Mobile manipulator is very suitable for replacing the people to be operated in various dangerous situations, as get rid of explosive, garbage disposal, field exploration and space operation etc., be suitable for handling that the industrial problem of various complexity such as the mobile manipulator welding of argosy housing are made etc., be suitable for expanding the service range with people's interactive collaboration, as the operation elevator, open the door, carry object etc.The mobile robot etc. that delivers letters of the Mars Pathfinder who succeeded in developing in succession in the last few years, the manipulator of getting rid of the danger, mobile welding tool hand, office belongs to typical mobile manipulator.Increasingly mature along with technology such as relevant robot, control automatically, computer visions, mobile manipulator will can play an important role in field widely.
Mobile manipulator generally comprises: mobile platform, manipulator, sensor and control system etc.The mobile platform of working in flat road surface environment such as office adopts wheeled driving, then is comprehensive mobile platform if can realize the motion of whole 3 frees degree (all around, rotation) on the plane, otherwise is non-comprehensive mobile platform.The structure of manipulator can be very simple, also can adopt the articulated type industry mechanical arm of 6DOF to realize the extracting and the operation task of any attitude.Sensor generally includes ultrasonic wave, infrared, vision sensor etc., is used for the perception external environmental information to realize the location, keep away function such as barrier.Control system is made up of computer and control card etc. usually, realizes that the signal of sensor is handled, the coordination control of mobile platform and manipulator.
On the system constructing of mobile manipulator, generally be that mobile platform and manipulator are combined simply, do not consider overall system structure and optimization in Properties.A kind of simple mobile manipulator comprises mobile platform and simple clamper, and basic structure and function class are like fork truck.As (T.G.Sugar such as V.Kumar, and V.Kumar, Control of cooperating mobilemanipulators.IEEE Transactions on Robotics and Automation, 2002,18 (1): 94-103) Yan Zhi system comprises a comprehensive mobile platform and a clip, and, can be used for realizing simple object transport function at the 3DOF flexible manipulator of plane motion.The most function singleness of this mobile manipulator, the operating space is limited, mobile platform fixedly the time manipulator be difficult to play a role.
The kinematic accuracy of manipulator is better than mobile platform generally speaking, and therefore if target in the working space scope of manipulator, can only be finished the work by the manipulator, this just requires manipulator to have complicated structure and rich functions.A kind of simple thinking is exactly that industry mechanical arm product with maturation combines with mobile platform.(J.D.Tan such as N.Xi, and N.Xi, Unifiedmodel approach for planning and control of mobile manipulators.Proceedings of the 2001 IEEE International Conference on Roboticsand Automation, 2001,3:3145-3152) mobile manipulator that is adopted is fixed on the comprehensive mobile platform by industry mechanical arm Puma560 and constitutes.(T.Takubo such as K.Tanie, H.Arai, and K.Tanie, Control of mobile manipulator using a virtualimpedance wall.Proceedings of the IEEE International Conferenceon Robotics and Automation, 2002,4:3571-3576) adopt the manipulator of a comprehensive mobile platform and 7 frees degree to constitute mobile manipulator.(Kim such as Kim, etc.Visualsensing and recognition of welding environment for intelligentshipyard welding robots.IEEE Int.Conf.on Intelligent Robots andSystems, 2000,3:2159-2165) then with this similar system applies to the construction of large ship housing, at arm end identification and the tracking that the three-dimensional structure optical sensor is realized track has been installed.Above method has fully realized the shift operation functionality of mobile manipulator owing to adopted ripe industry mechanical arm technology.But also there are some problems: the installation site that on mobile platform, can not find suitable vision system, do not sheltered from angular field of view by manipulator, it is exactly working space conflict with manipulator, if lack the location of the overall situation accurately that vision system then is difficult to realize mobile manipulator, if vision system is installed in arm end, the angular field of view and the effect of vision system have then been limited to a great extent; The industry mechanical arm quality is big, movement velocity is fast, can produce very big bonding force in the motion process and act on the mobile platform, influence the stable of platform, causes that easily platform vibrates or tumbles; The energy resource consumption of industry mechanical arm is very big, is the main burden of the vehicle-mounted energy of mobile platform.
The specific embodiment
3 frees degree of mobile platform are meant its all around in the plane and 3 kinds of forms of motion of rotation; realize comprehensive moving in the plane; especially also can freedom of movement in narrow space, therefore, be in favourable direction in the time of guaranteeing Robot actions.Except wheel, motor, driver and driving power, mobile platform also comprises sonac and infrared sensor etc., can be used for realizing the Primary Location of mobile platform.
Manipulator consists of the following components: trunk, shoulder, upper arm, forearm, wrist and hand.And the joint that connects each several part, comprise 1 linear joint, as moving up and down and 4 cradle heads such as shoulder joint, elbow joint, wrist rotation joint and wrist swinging joint, totally 5 frees degree of line slideway (trunk) top shoe.By the coordinated movement of various economic factors in each joint, can control arm end (hand) and move to assigned address, realize the function that grasps and operate.During to the target grand movement, each connecting rod of manipulator will be in the initial reset position at mobile platform, and its each several part does not exceed mobile platform and collides with external environment avoiding.Treating the operation object by vision system in the motion process of mobile platform positions.If object is in the operating space of manipulator, then the manipulator setting in motion is executed the task.If can't effectively finish the work by the motion of manipulator separately, then control the mobile platform coordinated movement of various economic factors.
The another one pith of finishing move operation is a vision system, be installed on the trunk of manipulator, absorb the image of external environment, obtain the positional information of waiting to operate object by image process method, and offer the control system of mobile manipulator, as the foundation of output control action.
Below in conjunction with accompanying drawing the present invention is described further.
Comprehensive mobile platform 6, can be implemented in the motion of 3 frees degree of all around and rotation on the plane, wherein sonac, infrared sensor etc. be installed in mobile platform 6 around, be used for detecting external environment information, realize mobile platform motion planning, keep away function such as barrier.Consider mobile platform structure and kinetic characteristic in the design process of manipulator, introduced the mode that linear joint and cradle head combine, this is one of main feature of the present invention.Because the shoulder and the elbow joint of manipulator all rotate in horizontal plane around vertical axis, therefore guaranteed that the visual angle of video camera 9 do not blocked by manipulator, be convenient to when Robot actions, accurately judge the terminal pose of manipulator by vision system, by the trunk of line slideway 5 as manipulator, guide rail slide block 4 can move up and down on line slideway 5.Line slideway 5 can be used as the bearing of video camera 9 simultaneously, and the position that makes video camera 9 is fixing with respect to mobile platform 6, when having avoided vision system to be installed in arm end, because the limited influence to positioning accuracy that produces with motion oscillations etc. in visual angle.Shoulder 3 is fixed on the guide rail slide block 4, and the junction of upper arm 2 and shoulder 3 is a shoulder joint, and upper arm 2 can be rotated at horizontal plane around vertical axis.If the distance of the center of rotation of shoulder joint and mobile platform 6 equals zero, then mobile platform 6 rotational freedoms overlap with the shoulder joint rotational freedom, unusual appearance occurs.But in present design, the center of line slideway 5 overlaps with the center of rotation of mobile platform 6, shoulder joint from the distance at line slideway 5 centers greater than zero, thereby avoided unusual appearance.Junction between forearm 1 and the upper arm 2 is an elbow joint, and forearm 1 can be rotated at horizontal plane around vertical axis equally.The junction of forearm 1 and wrist 8 is wrist rotation joint, and its rotating shaft direction is with forearm 1 axis direction unanimity, and is vertical with the axis direction of elbow joint with shoulder.The junction of wrist 8 and hand 7 is the wrist swinging joint, and its turning cylinder is vertical with wrist rotation joints axes direction.When the wrist angle of rotation was zero, shoulder, elbow joint were parallel with the axis of wrist swinging joint.Manipulator attitude shown in Fig. 1 is that 90 degree have been rotated in wrist rotation joint, and the wrist swinging joint has been rotated 45 degree.
If the wrist rotation joint angle of manipulator is fixed as zero, then manipulator is equivalent to a kind of typical SCARA manipulator, comprises that 1 moves up and down and 3 frees degree of rotating in horizontal plane around vertical axis.It is axis that manipulator working space maximum forward can reach with the shoulder joint, and arm length is a radius, and slide block 4 movement travels are the cylindrical space of height.The SCARA manipulator is widely used on the grasping manipulation of flow production line product, its major advantage comprises: mobile manipulator can be avoided the effect of gravity to manipulator in the rotation of horizontal plane, reduce motion oscillations effectively, obtain very high positioning accuracy and desirable manipulator dynamics; Do not need very high-power and drive motors moment of torsion yet, alleviated motor and quality, the quality of arm and the quality of whole manipulator, reduced the burden of mobile platform 6 drive energies.
If the wrist rotation joint angle of manipulator changes, can change the attitude of arm end with the cooperation of wrist swinging joint, the level that is not limited to is pointed to, and therefore can come operating surface direction off plumb object with attitude more suitably, as presses button on the horizontal plane, shakes hands etc. with the people.Can also realize operating the fine adjustments of height, and needn't drive the height that slide block 4 is adjusted manipulator, reduce the consumption of drive energy effectively.
Reset to original state when manipulator is not worked, as Fig. 2, whole manipulator all is recovered in the mobile platform 6, is convenient to the fast moving of mobile platform 6 towards distant object, and manipulator is collided with external environment.Wherein upper arm 2 rotates to the vertical position of forward direction, and the length of upper arm 2 is less than mobile platform 6 radiuses, with the arbitrary portion that guarantees upper arm 2 when the reset position all in platform.Forearm 1 is retracted to the maximum position that does not bump with upper arm 2, and the length of forearm 1 is greater than upper arm 2 length, in the several connecting rods of arm for the longest, the length of forearm 1 and ancon and be no more than mobile platform 6.Wrist 8 angle of rotation are zero, and hand 7 equally inwardly is retracted to the maximum position of different wrist 8 collisions, and the length of hand can in very large range change, and being no more than mobile platform 6 when regaining to satisfy is standard.The length of each connecting rod arm size with human body basically is suitable.
Vision system adopts the video camera 9 with rotation, pitching function.Make that the high accuracy rotation by video camera 9 realizes the observation of scenery on every side under the motionless situation of mobile platform 6.When manipulator is in low operating position, can control video camera 9 and overlook, guarantee that arm end is in the angular field of view of video camera 9.If carry out overall situation location by ceiling light, also can control video camera 9 elevations angle, take the image in the place ahead on the mobile manipulator.
Computer control system is installed in the inside of mobile platform, be used for carrying out the processing of ultrasonic, infrared sensor Signal Processing and visual pattern, calculate the position of target, and the control command of the output mobile platform and the manipulator coordinated movement of various economic factors, be effective the function of finishing move operation.
The display 11 of computer control system is installed in the back side of manipulator, can be used for showing the dynamic image that video camera 9 is taken, and the positional information of mobile platform in entire environment etc., be convenient to the monitoring debugging of operating personnel to whole system.