Method and system for collision avoidance

Abstract

A method for collision avoidance for a host vehicle includes the following steps; receiving input data relating to a set of objects external to the host vehicle, wherein an object position (r,φ), and an object velocity ({dot over (r)}) are associated with each object by a sensor system arranged on the host vehicle, then estimating future trajectories of each external object, while considering influence by the future trajectories of the other external objects.

1 ) Method for collision avoidance for a host vehicle ( 20 ) comprising the following method steps:
 receiving input data relating to a set of objects external to said host vehicle, said objects being positioned within a detecting range of a sensor system arranged on said host vehicle, wherein an object position (r,φ), and an object velocity ({dot over (r)}) are associated with each object in said set of objects by said sensor system ( 18 ), said input data defining a current state of each object,   estimating future trajectories of each external object, while considering influence by the future trajectories of the other external objects;   characterised in that the further method steps are performed:
 determining, by use of a lane exit control block, whether the driver is making an attempt to exit a lane; 
 determining, by use of a future conflict estimator control block, if the future trajectory of the host vehicle is involved in a conflicting event in a neighbouring lane; 
 applying, by the use of a lane change prevention unit, a torque in the direction against a torque generated by a driver to effect a lane change in the event said future conflict estimator control block detects a conflict event of relevance for the host vehicle in the lane into which the driver attempts to enter. 
   
     
     
         2 ) A method according to  claim 1 , characterised in that the method step of estimating future trajectories of each external object, while considering influence by the future trajectories of the other external objects includes the steps of:
 associating a plurality of future control input signals with each moving object, where each future control signal will generate together with the current state of each moving object a separate future path in a state update equation,   determining, by the use of a future trajectory estimator, future trajectories for each of the objects, by selecting one of the most probable future paths as the future trajectory,   
     
     
         3 ) A method according to  claim 2 , characterised in that, for each moving object, the most probable path is selected as the future trajectory. 
     
     
         4 ) A method according to  claim 2 , characterised in that each of said future control input signals include a one or more dimensional variable. 
     
     
         5 ) A method according to  claim 4 , characterised in that each of said future control input signal includes the variables acceleration (a) and steering angle (θ). 
     
     
         6 ) A method according to  claim 5 , characterised in that each of said future control input signal is constituted by the variables acceleration (a) and steering angle (θ). 
     
     
         7 ) A method according to  claim 4 , characterised in that said plurality of future paths for each moving object are generated by, at each step in a plurality of discrete time steps together forming a prediction horizon, selecting a plurality of values of each variable, wherein said values are selected within a predetermined interval. 
     
     
         8 ) A method according to  claim 7 , characterised in that a probability number is associated with each value of the variable. 
     
     
         9 ) A method according to  claim 8 , characterised in that an aggregate probability for each future path at the prediction horizon is calculated. 
     
     
         10 ) A method according to  claim 7 , characterised in that said plurality of values of each variable are selected by random. 
     
     
         11 ) A method according to  claim 2  characterised in that any future path generating a conflicting event between the future trajectory paths of at least two objects, will be rejected as improbable future trajectory paths for the objects involved. 
     
     
         12 ) A method according to  claim 1 , characterised in that in the event a future trajectory of the host vehicle in the current lane is involved in a conflicting event, interception of the lane change prevention unit is prevented such that a torque will not be applied in the direction against a torque generated by a driver to effect a lane change even in the case where said future conflict estimator control block detects a conflict event of relevance for the host vehicle in the lane into which the driver attempts to enter. 
     
     
         13 ) A method according to  claim 1 , characterised in that said future trajectory estimator determines whether any of these future trajectories will mutually effect each other due to a risk of conflict in between the future trajectories of at least one pair of objects which is arranged to; and 
     
     
         14 ) A method according to  claim 13 , characterised in that said future conflict estimator control block furthermore determines if a future trajectory of the host vehicle in a current lane of the host vehicle does not include any conflicting events with external objects and that said on board system for collision avoidance only allows said lane change prevention unit to prevent lane change if no conflicting events with external objects are detected in the current lane of the host vehicle. 
     
     
         15 ) A method according to  claim 13 , characterised in that an object and road tracking block processes output data from the sensor system in a state estimator which estimates the states of all external objects, the host vehicle and the road geometry. 
     
     
         16 ) A method according to  claim 13  characterised in that said future trajectory estimator corrects the future trajectory of an external object in order to avoid a conflict, when a conflict event between two external objects is detected. 
     
     
         17 ) A method according to  claim 13  characterised in that said future trajectory estimator determines the locus of the conflicting event and determines whether this conflict event will have an impact of the host vehicle or not. 
     
     
         18 ) An on board system for collision avoidance comprising
 a sensor system arranged on a host vehicle, said sensor system being arranged to receive input data relating to a set of objects external to said host vehicle, said objects being positioned within a detecting range of said sensor system, wherein an object position (r,φ), and an object velocity ({dot over (r)}) are associated with each object in said set of objects, said input data defining a current state of each object; and   a future trajectory estimator arranged for estimating future trajectories of each external object, while considering influence by the future trajectories of the other external objects;   characterised in that the on board system for collision avoidance further includes:
 a lane exit control block arranged do determine whether the driver is making an attempt to exit the lane; 
 a future conflict estimator control block arranged to determine if the future trajectory of the host vehicle is involved in a conflicting event; and 
 a lane change prevention unit arranged to apply a torque in the direction against a torque generated by a driver to effect a lane change in the event said future conflict estimator control block detects a conflict event of relevance for the host vehicle in the lane into which the driver attempts to enter. 
   
     
     
         19 ) An on board system for collision avoidance according to  claim 18 , characterised in that said future trajectory estimator is arranged to estimate future trajectories of each external object, while considering influence by the future trajectories of the other external objects by:
 associating a plurality of future control input signals with each moving object, where each future control signal will generate together with the current state of each moving object a separate future path in a state update equation,   determining, by the use of a future trajectory estimator, future trajectories for each of the objects, by selecting one of the most probable future paths as the future trajectory,   
     
     
         20 ) An on board system for collision avoidance according to  claim 19 , characterised in that, for each moving object, the most probable path is selected as the future trajectory. 
     
     
         21 ) An on board system for collision avoidance according to  claim 19 , characterised in that each of said future control input signal includes a one or more dimensional variable. 
     
     
         22 ) An on board system for collision avoidance according to  claim 21 , characterised in that each of said future control input signal includes the variables acceleration (a) and steering angle (θ). 
     
     
         23 ) An on board system for collision avoidance according to  claim 22 , characterised in that each of said future control input signal is constituted by the variables acceleration (a) and steering angle (θ). 
     
     
         24 ) An on board system for collision avoidance according to  claim 21 , characterised in that said plurality of future paths for each moving object are generated by, at each step in a plurality of discrete time steps together forming a prediction horizon, selecting a plurality of values of each variable, wherein said values are selected within a predetermined interval. 
     
     
         25 ) An on board system for collision avoidance according to  claim 24 , characterised in that a probability number is associated with each value of the variable. 
     
     
         26 ) An on board system for collision avoidance according to  claim 25 , characterised in that an aggregate probability for each future path at the prediction horizon is calculated. 
     
     
         27 ) An on board system for collision avoidance according to  claim 24 , characterised in that said plurality of values of each variable are selected by random. 
     
     
         28 ) An on board system for collision avoidance according to  claims 19 , characterised in that any future path generating a conflicting event between the future trajectory paths of at least two objects, will be rejected as improbable future trajectory paths for the objects involved. 
     
     
         29 ) An on board system for collision avoidance according to  claim 18 , characterised in that in the event a future trajectory of the host vehicle in the current lane is involved in a conflicting event, interception of the lane change prevention unit is prevented such that a torque will not be applied in the direction against a torque generated by a driver to effect a lane change even in the case where said future conflict estimator control block detects a conflict event of relevance for the host vehicle in the lane into which the driver attempts to enter. 
     
     
         30 ) An on board system for collision avoidance according to  claim 18 , characterised in that said future trajectory estimator is arranged to determine whether any of these future trajectories will mutually effect each other due to a risk of conflict in between the future trajectories of at least one pair of objects 
     
     
         31 ) An on board system for collision avoidance according to  claim 30 , characterised in that said future conflict estimator control block is furthermore arranged to determine if a future trajectory of the host vehicle in a current lane of the host vehicle does not include any conflicting events with external objects and that said on board system for collision avoidance is arranged to only allow said lane change prevention unit to prevent lane change if no conflicting events with external objects are detected in the current lane of the host vehicle. 
     
     
         32 ) An on board system for collision avoidance according to  claim 30 , characterised in that an object and road tracking block is arranged to process output data from the sensor system in a state estimator which estimates the states of all external objects, the host vehicle and the road geometry. 
     
     
         33 ) An on board system for collision avoidance according to  claim 30 , characterised in that said future trajectory estimator is arranged correct to the future trajectory of an external object in order to avoid a conflict, when a conflict event between two external objects is detected. 
     
     
         34 ) An on board system for collision avoidance according to  claim 30 , characterised in that said future trajectory estimator is arranged to determine the locus of the conflicting event and to determine whether this conflict event will have an impact of the host vehicle or not.