Mujoco核心数据结构-mjData mjModel

Defined in mjdata.h
This is the data structure holding information about one solver iteration. mjData.solver is a preallocated array of mjSolverStat data structures, one for each iteration of the solver, up to a maximum of mjNSOLVER. The actual number of solver iterations is given by mjData.solver_iter.

struct _mjData
{
   
   
    // constant sizes
    int nstack;                     // number of mjtNums that can fit in stack
    int nbuffer;                    // size of main buffer in bytes

    // stack pointer
    int pstack;                     // first available mjtNum address in stack

    // memory utilization stats
    int maxuse_stack;               // maximum stack allocation
    int maxuse_con;                 // maximum number of contacts
    int maxuse_efc;                 // maximum number of scalar constraints

    // diagnostics
    mjWarningStat warning[mjNWARNING]; // warning statistics
    mjTimerStat timer[mjNTIMER];       // timer statistics
    mjSolverStat solver[mjNSOLVER];    // solver statistics per iteration
    int solver_iter;                // number of solver iterations
    int solver_nnz;                 // number of non-zeros in Hessian or efc_AR
    mjtNum solver_fwdinv[2];        // forward-inverse comparison: qfrc, efc

    // variable sizes
    int ne;                         // number of equality constraints
    int nf;                         // number of friction constraints
    int nefc;                       // number of constraints
    int ncon;                       // number of detected contacts

    // global properties
    mjtNum time;                    // simulation time
    mjtNum energy[2];               // potential, kinetic energy

    //-------------------------------- end of info header

    // buffers
    void*     buffer;               // main buffer; all pointers point in it    (nbuffer bytes)
    mjtNum*   stack;                // stack buffer                             (nstack mjtNums)

    //-------------------------------- main inputs and outputs of the computation

    // state
    mjtNum*   qpos;                 // position                                 (nq x 1)
    mjtNum*   qvel;                 // velocity                                 (nv x 1)
    mjtNum*   act;                  // actuator activation                      (na x 1)
    mjtNum*   qacc_warmstart;       // acceleration used for warmstart          (nv x 1)

    // control
    //0 = torque actuator,1=position servo,2= velocity servo
    mjtNum*   ctrl;                 // control                                  (nu x 1)
    mjtNum*   qfrc_applied;         // applied ge`neralized force`                (nv x 1)
    mjtNum*   xfrc_applied;         // applied Cartesian force/torque           (nbody x 6)

    // dynamics
    //M*qacc + qfrc_bias = qfrc_applied + ctrl中的qacc，加速度
    mjtNum*   qacc;                 // acceleration                             (nv x 1)
    mjtNum*   act_dot;              // time-derivative of actuator activation   (na x 1)

    // mocap data
    mjtNum*  mocap_pos;             // positions of mocap bodies                (nmocap x 3)
    mjtNum*  mocap_quat;            // orientations of mocap bodies             (nmocap x 4)

    // user data
    mjtNum*  userdata;              // user data, not touched by engine         (nuserdata x 1)

    // sensors
    //传感器是3x1，即一个传感器就有3个数据x,y,z，如果感应的是速度，则是dx,dy,dz
    //传感器类型：framepos=感应位置，framelinvel感应速度
    mjtNum*  sensordata;            // sensor data array                        (nsensordata x 1)

    //-------------------------------- POSITION dependent

    // computed by mj_fwdPosition/mj_kinematics
    mjtNum*   xpos;                 // Cartesian position of body frame         (nbody x 3)
    mjtNum*   xquat;                // Cartesian orientation of body frame      (nbody x 4)
    mjtNum*   xmat;                 // Cartesian orientation of body frame      (nbody x 9)
    mjtNum*   xipos;                // Cartesian position of body com           (nbody x 3)
    mjtNum*   ximat;                // Cartesian orientation of body inertia    (nbody x 9)
    mjtNum*   xanchor;              // Cartesian position of joint anchor       (njnt x 3)
    mjtNum*   xaxis;                // Cartesian joint axis                     (njnt x 3)
    mjtNum*   geom_xpos;            // Cartesian geom position                  (ngeom x 3)
    mjtNum*   geom_xmat;            // Cartesian geom orientation               (ngeom x 9)
    mjtNum*   site_xpos;            // Cartesian site position                  (nsite x 3)
    mjtNum*   site_xmat;            // Cartesian site orientation               (nsite x 9)
    mjtNum*   cam_xpos;             // Cartesian camera position                (ncam x 3)
    mjtNum*   cam_xmat;             // Cartesian camera orientation             (ncam x 9)
    mjtNum*   light_xpos;           // Cartesian light position                 (nlight x 3)
    mjtNum*   light_xdir;           // Cartesian light direction                (nlight x 3)